From 6939ad25d9b109d3a11c783815f3ee1fbdf6d6aa Mon Sep 17 00:00:00 2001 From: James Devine Date: Fri, 29 Jan 2016 13:57:34 +0000 Subject: [PATCH 1/6] microbit: formatting changes to MicroBitFiber Corrected whitespace in MicroBitFiber. --- source/MicroBitFiber.cpp | 168 +++++++++++++++++++-------------------- 1 file changed, 84 insertions(+), 84 deletions(-) diff --git a/source/MicroBitFiber.cpp b/source/MicroBitFiber.cpp index 26816de..aabea0f 100644 --- a/source/MicroBitFiber.cpp +++ b/source/MicroBitFiber.cpp @@ -6,7 +6,7 @@ * 1) To provide a clean abstraction for application languages to use when building async behaviour (callbacks). * 2) To provide ISR decoupling for Messagebus events generted in an ISR context. */ - + #include "MicroBit.h" /* @@ -37,7 +37,7 @@ unsigned long ticks = 0; uint8_t fiber_flags = 0; /** - * Utility function to add the currenty running fiber to the given queue. + * Utility function to add the currenty running fiber to the given queue. * Perform a simple add at the head, to avoid complexity, * Queues are normally very short, so maintaining a doubly linked, sorted list typically outweighs the cost of * brute force searching. @@ -62,7 +62,7 @@ void queue_fiber(Fiber *f, Fiber **queue) } else { - // Scan to the end of the queue. + // Scan to the end of the queue. // We don't maintain a tail pointer to save RAM (queues are nrmally very short). Fiber *last = *queue; @@ -78,7 +78,7 @@ void queue_fiber(Fiber *f, Fiber **queue) } /** - * Utility function to the given fiber from whichever queue it is currently stored on. + * Utility function to the given fiber from whichever queue it is currently stored on. * @param f the fiber to remove. */ void dequeue_fiber(Fiber *f) @@ -87,34 +87,34 @@ void dequeue_fiber(Fiber *f) if (f->queue == NULL) return; - // Remove this fiber fromm whichever queue it is on. + // Remove this fiber fromm whichever queue it is on. __disable_irq(); - + if (f->prev != NULL) f->prev->next = f->next; else *(f->queue) = f->next; - + if(f->next) f->next->prev = f->prev; - + f->next = NULL; f->prev = NULL; f->queue = NULL; - + __enable_irq(); } /** * Allocates a fiber from the fiber pool if availiable. Otherwise, allocates a new one from the heap. - */ + */ Fiber *getFiberContext() { Fiber *f; - + __disable_irq(); - + if (fiberPool != NULL) { f = fiberPool; @@ -124,17 +124,17 @@ Fiber *getFiberContext() else { __enable_irq(); - + f = new Fiber(); - + if (f == NULL) return NULL; f->stack_bottom = 0; f->stack_top = 0; - } - - // Ensure this fiber is in suitable state for reuse. + } + + // Ensure this fiber is in suitable state for reuse. f->flags = 0; f->tcb.stack_base = CORTEX_M0_STACK_BASE; @@ -143,7 +143,7 @@ Fiber *getFiberContext() /** - * Initialises the Fiber scheduler. + * Initialises the Fiber scheduler. * Creates a Fiber context around the calling thread, and adds it to the run queue as the current thread. * * This function must be called once only from the main thread, and before any other Fiber operation. @@ -152,14 +152,14 @@ void scheduler_init() { // Create a new fiber context currentFiber = getFiberContext(); - + // Add ourselves to the run queue. queue_fiber(currentFiber, &runQueue); // Create the IDLE fiber. // Configure the fiber to directly enter the idle task. idleFiber = getFiberContext(); - idleFiber->tcb.SP = CORTEX_M0_STACK_BASE - 0x04; + idleFiber->tcb.SP = CORTEX_M0_STACK_BASE - 0x04; idleFiber->tcb.LR = (uint32_t) &idle_task; // Register to receive events in the NOTIFY channel - this is used to implement wait-notify semantics @@ -172,36 +172,36 @@ void scheduler_init() /** * Timer callback. Called from interrupt context, once every FIBER_TICK_PERIOD_MS milliseconds. - * Simply checks to determine if any fibers blocked on the sleep queue need to be woken up + * Simply checks to determine if any fibers blocked on the sleep queue need to be woken up * and made runnable. */ void scheduler_tick() { Fiber *f = sleepQueue; Fiber *t; - + // increment our real-time counter. ticks += FIBER_TICK_PERIOD_MS; // Check the sleep queue, and wake up any fibers as necessary. while (f != NULL) { - t = f->next; - + t = f->next; + if (ticks >= f->context) { // Wakey wakey! dequeue_fiber(f); queue_fiber(f,&runQueue); } - + f = t; } } /** - * Event callback. Called from the message bus whenever an event is raised. - * Checks to determine if any fibers blocked on the wait queue need to be woken up + * Event callback. Called from the message bus whenever an event is raised. + * Checks to determine if any fibers blocked on the wait queue need to be woken up * and made runnable due to the event. */ void scheduler_event(MicroBitEvent evt) @@ -209,20 +209,20 @@ void scheduler_event(MicroBitEvent evt) Fiber *f = waitQueue; Fiber *t; int notifyOneComplete = 0; - + // Check the wait queue, and wake up any fibers as necessary. while (f != NULL) { - t = f->next; - - // extract the event data this fiber is blocked on. + t = f->next; + + // extract the event data this fiber is blocked on. uint16_t id = f->context & 0xFFFF; uint16_t value = (f->context & 0xFFFF0000) >> 16; - + // Special case for the NOTIFY_ONE channel... if ((evt.source == MICROBIT_ID_NOTIFY_ONE && id == MICROBIT_ID_NOTIFY) && (value == MICROBIT_EVT_ANY || value == evt.value)) { - if (!notifyOneComplete) + if (!notifyOneComplete) { // Wakey wakey! dequeue_fiber(f); @@ -238,7 +238,7 @@ void scheduler_event(MicroBitEvent evt) dequeue_fiber(f); queue_fiber(f,&runQueue); } - + f = t; } @@ -250,9 +250,9 @@ void scheduler_event(MicroBitEvent evt) /** * Blocks the calling thread for the given period of time. - * The calling thread will be immediatley descheduled, and placed onto a - * wait queue until the requested amount of time has elapsed. - * + * The calling thread will be immediatley descheduled, and placed onto a + * wait queue until the requested amount of time has elapsed. + * * n.b. the fiber will not be be made runnable until after the elasped time, but there * are no guarantees precisely when the fiber will next be scheduled. * @@ -269,8 +269,8 @@ void fiber_sleep(unsigned long t) // Allocate a new fiber. This will come from the fiber pool if availiable, // else a new one will be allocated on the heap. forkedFiber = getFiberContext(); - - // If we're out of memory, there's nothing we can do. + + // If we're out of memory, there's nothing we can do. // keep running in the context of the current thread as a best effort. if (forkedFiber != NULL) f = forkedFiber; @@ -278,22 +278,22 @@ void fiber_sleep(unsigned long t) // Calculate and store the time we want to wake up. f->context = ticks + t; - + // Remove fiber from the run queue dequeue_fiber(f); - + // Add fiber to the sleep queue. We maintain strict ordering here to reduce lookup times. queue_fiber(f, &sleepQueue); - + // Finally, enter the scheduler. schedule(); } /** * Blocks the calling thread until the specified event is raised. - * The calling thread will be immediatley descheduled, and placed onto a + * The calling thread will be immediatley descheduled, and placed onto a * wait queue until the requested event is received. - * + * * n.b. the fiber will not be be made runnable until after the event is raised, but there * are no guarantees precisely when the fiber will next be scheduled. * @@ -311,8 +311,8 @@ void fiber_wait_for_event(uint16_t id, uint16_t value) // Allocate a TCB from the new fiber. This will come from the tread pool if availiable, // else a new one will be allocated on the heap. forkedFiber = getFiberContext(); - - // If we're out of memory, there's nothing we can do. + + // If we're out of memory, there's nothing we can do. // keep running in the context of the current thread as a best effort. if (forkedFiber != NULL) f = forkedFiber; @@ -320,13 +320,13 @@ void fiber_wait_for_event(uint16_t id, uint16_t value) // Encode the event data in the context field. It's handy having a 32 bit core. :-) f->context = value << 16 | id; - + // Remove ourselve from the run queue dequeue_fiber(f); - + // Add ourselves to the sleep queue. We maintain strict ordering here to reduce lookup times. queue_fiber(f, &waitQueue); - + // Register to receive this event, so we can wake up the fiber when it happens. // Special case for teh notify channel, as we always stay registered for that. if (id != MICROBIT_ID_NOTIFY && id != MICROBIT_ID_NOTIFY_ONE) @@ -337,16 +337,16 @@ void fiber_wait_for_event(uint16_t id, uint16_t value) } /** - * Executes the given function asynchronously. - * + * Executes the given function asynchronously. + * * Fibers are often used to run event handlers, however many of these event handlers are very simple functions * that complete very quickly, bringing unecessary RAM overhead. * - * This function takes a snapshot of the current processor context, then attempts to optimistically call the given function directly. - * We only create an additional fiber if that function performs a block operation. + * This function takes a snapshot of the current processor context, then attempts to optimistically call the given function directly. + * We only create an additional fiber if that function performs a block operation. * * @param entry_fn The function to execute. - * @return MICROBIT_OK, or MICROBIT_INVALID_PARAMETER. + * @return MICROBIT_OK, or MICROBIT_INVALID_PARAMETER. */ int invoke(void (*entry_fn)(void)) { @@ -361,14 +361,14 @@ int invoke(void (*entry_fn)(void)) create_fiber(entry_fn); return MICROBIT_OK; } - + // Snapshot current context, but also update the Link Register to // refer to our calling function. save_register_context(¤tFiber->tcb); // If we're here, there are two possibilities: // 1) We're about to attempt to execute the user code - // 2) We've already tried to execute the code, it blocked, and we've backtracked. + // 2) We've already tried to execute the code, it blocked, and we've backtracked. // If we're returning from the user function and we forked another fiber then cleanup and exit. if (currentFiber->flags & MICROBIT_FIBER_FLAG_PARENT) @@ -382,7 +382,7 @@ int invoke(void (*entry_fn)(void)) // execute the function directly. If the code tries to block, we detect this and // spawn a thread to deal with it. currentFiber->flags |= MICROBIT_FIBER_FLAG_FOB; - entry_fn(); + entry_fn(); currentFiber->flags &= ~MICROBIT_FIBER_FLAG_FOB; // If this is is an exiting fiber that for spawned to handle a blocking call, recycle it. @@ -394,17 +394,17 @@ int invoke(void (*entry_fn)(void)) } /** - * Executes the given parameterized function asynchronously. - * + * Executes the given parameterized function asynchronously. + * * Fibers are often used to run event handlers, however many of these event handlers are very simple functions * that complete very quickly, bringing unecessary RAM overhead. * - * This function takes a snapshot of the current processor context, then attempt to optimistically call the given function directly. - * We only create an additional fiber if that function performs a block operation. + * This function takes a snapshot of the current processor context, then attempt to optimistically call the given function directly. + * We only create an additional fiber if that function performs a block operation. * * @param entry_fn The function to execute. * @param param an untyped parameter passed into the entry_fn. - * @return MICROBIT_OK, or MICROBIT_INVALID_PARAMETER. + * @return MICROBIT_OK, or MICROBIT_INVALID_PARAMETER. */ int invoke(void (*entry_fn)(void *), void *param) { @@ -419,14 +419,14 @@ int invoke(void (*entry_fn)(void *), void *param) create_fiber(entry_fn, param); return MICROBIT_OK; } - + // Snapshot current context, but also update the Link Register to // refer to our calling function. save_register_context(¤tFiber->tcb); // If we're here, there are two possibilities: // 1) We're about to attempt to execute the user code - // 2) We've already tried to execute the code, it blocked, and we've backtracked. + // 2) We've already tried to execute the code, it blocked, and we've backtracked. // If we're returning from the user function and we forked another fiber then cleanup and exit. if (currentFiber->flags & MICROBIT_FIBER_FLAG_PARENT) @@ -440,7 +440,7 @@ int invoke(void (*entry_fn)(void *), void *param) // execute the function directly. If the code tries to block, we detect this and // spawn a thread to deal with it. currentFiber->flags |= MICROBIT_FIBER_FLAG_FOB; - entry_fn(param); + entry_fn(param); currentFiber->flags &= ~MICROBIT_FIBER_FLAG_FOB; // If this is is an exiting fiber that for spawned to handle a blocking call, recycle it. @@ -480,26 +480,26 @@ Fiber *__create_fiber(uint32_t ep, uint32_t cp, uint32_t pm, int parameterised) // Validate our parameters. if (ep == 0 || cp == 0) return NULL; - + // Allocate a TCB from the new fiber. This will come from the fiber pool if availiable, // else a new one will be allocated on the heap. Fiber *newFiber = getFiberContext(); - + // If we're out of memory, there's nothing we can do. if (newFiber == NULL) return NULL; - + newFiber->tcb.R0 = (uint32_t) ep; newFiber->tcb.R1 = (uint32_t) cp; newFiber->tcb.R2 = (uint32_t) pm; // Set the stack and assign the link register to refer to the appropriate entry point wrapper. - newFiber->tcb.SP = CORTEX_M0_STACK_BASE - 0x04; + newFiber->tcb.SP = CORTEX_M0_STACK_BASE - 0x04; newFiber->tcb.LR = parameterised ? (uint32_t) &launch_new_fiber_param : (uint32_t) &launch_new_fiber; - + // Add new fiber to the run queue. queue_fiber(newFiber, &runQueue); - + return newFiber; } @@ -507,7 +507,7 @@ Fiber *__create_fiber(uint32_t ep, uint32_t cp, uint32_t pm, int parameterised) * Creates a new Fiber, and launches it. * * @param entry_fn The function the new Fiber will begin execution in. - * @param completion_fn The function called when the thread completes execution of entry_fn. + * @param completion_fn The function called when the thread completes execution of entry_fn. * @return The new Fiber. */ Fiber *create_fiber(void (*entry_fn)(void), void (*completion_fn)(void)) @@ -521,7 +521,7 @@ Fiber *create_fiber(void (*entry_fn)(void), void (*completion_fn)(void)) * * @param entry_fn The function the new Fiber will begin execution in. * @param param an untyped parameter passed into the entry_fn anf completion_fn. - * @param completion_fn The function called when the thread completes execution of entry_fn. + * @param completion_fn The function called when the thread completes execution of entry_fn. * @return The new Fiber. */ Fiber *create_fiber(void (*entry_fn)(void *), void *param, void (*completion_fn)(void *)) @@ -543,15 +543,15 @@ void release_fiber(void *) * Any fiber reaching the end of its entry function will return here for recycling. */ void release_fiber(void) -{ +{ // Remove ourselves form the runqueue. dequeue_fiber(currentFiber); // Add ourselves to the list of free fibers queue_fiber(currentFiber, &fiberPool); - + // Find something else to do! - schedule(); + schedule(); } /** @@ -571,7 +571,7 @@ void verify_stack_size(Fiber *f) // Calculate the stack depth. stackDepth = f->tcb.stack_base - ((uint32_t) __get_MSP()); - // Calculate the size of our allocated stack buffer + // Calculate the size of our allocated stack buffer bufferSize = f->stack_top - f->stack_bottom; // If we're too small, increase our buffer size. @@ -624,10 +624,10 @@ void schedule() // Define the stack base of the forked fiber to be align with the entry point of the parent fiber forkedFiber->tcb.stack_base = currentFiber->tcb.SP; - // Ensure the stack allocation of the new fiber is large enough + // Ensure the stack allocation of the new fiber is large enough verify_stack_size(forkedFiber); - // Store the full context of this fiber. + // Store the full context of this fiber. save_context(&forkedFiber->tcb, forkedFiber->stack_top); // We may now be either the newly created thread, or the one that created it. @@ -638,7 +638,7 @@ void schedule() // If we're the new thread, we must have been unblocked by the scheduler, so simply return // and continue processing. - return; + return; } // We're in a normal scheduling context, so perform a round robin algorithm across runnable fibers. @@ -653,7 +653,7 @@ void schedule() else // Otherwise, just pick the head of the run queue. currentFiber = runQueue; - + if (currentFiber == idleFiber && oldFiber->flags & MICROBIT_FIBER_FLAG_DO_NOT_PAGE) { // Run the idle task right here using the old fiber's stack. @@ -676,12 +676,12 @@ void schedule() // Swap to the context of the chosen fiber, and we're done. // Don't bother with the overhead of switching if there's only one fiber on the runqueue! - if (currentFiber != oldFiber) + if (currentFiber != oldFiber) { // Special case for the idle task, as we don't maintain a stack context (just to save memory). if (currentFiber == idleFiber) { - idleFiber->tcb.SP = CORTEX_M0_STACK_BASE - 0x04; + idleFiber->tcb.SP = CORTEX_M0_STACK_BASE - 0x04; idleFiber->tcb.LR = (uint32_t) &idle_task; } @@ -692,7 +692,7 @@ void schedule() } else { - // Ensure the stack allocation of the fiber being scheduled out is large enough + // Ensure the stack allocation of the fiber being scheduled out is large enough verify_stack_size(oldFiber); // Schedule in the new fiber. From 6f812aa47493b06740c37a8b8519737a4b10cb38 Mon Sep 17 00:00:00 2001 From: James Devine Date: Fri, 29 Jan 2016 14:03:24 +0000 Subject: [PATCH 2/6] microbit: added new display mode, and accessor MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This commit introduces a new display mode, DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE, where the 4th render in every “frame” is dropped allowing for other components that use the display to use this dropped frame for processing. This is in preparation for Light Sensing on the 5x5 LED matrix. An accessor has also been added to MicroBitDisplay to check the current display mode! --- inc/MicroBitDisplay.h | 21 ++++++++++++++-- source/MicroBitDisplay.cpp | 49 ++++++++++++++++++++++++++++++++++---- 2 files changed, 63 insertions(+), 7 deletions(-) diff --git a/inc/MicroBitDisplay.h b/inc/MicroBitDisplay.h index 539569b..a96e497 100644 --- a/inc/MicroBitDisplay.h +++ b/inc/MicroBitDisplay.h @@ -12,6 +12,7 @@ */ #define MICROBIT_DISPLAY_EVT_ANIMATION_COMPLETE 1 #define MICROBIT_DISPLAY_EVT_FREE 2 +#define MICROBIT_DISPLAY_EVT_LIGHT_SENSE 4 /** * I/O configurations for common devices. @@ -43,6 +44,7 @@ #define MICROBIT_DISPLAY_COLUMN_COUNT 9 #define MICROBIT_DISPLAY_COLUMN_PINS P0_4, P0_5, P0_6, P0_7, P0_8, P0_9, P0_10, P0_11, P0_12 #define MICROBIT_DISPLAY_COLUMN_START P0_4 +#define MICROBIT_DISPLAY_ROW_START P0_13 #endif // @@ -55,6 +57,8 @@ #define MICROBIT_DISPLAY_GREYSCALE_BIT_DEPTH 8 #define MICROBIT_DISPLAY_ANIMATE_DEFAULT_POS -255 +#define MICROBIT_DISPLAY_ROW_RESET 0x20 + #include "mbed.h" #include "ManagedString.h" #include "MicroBitComponent.h" @@ -73,7 +77,8 @@ enum AnimationMode { enum DisplayMode { DISPLAY_MODE_BLACK_AND_WHITE, - DISPLAY_MODE_GREYSCALE + DISPLAY_MODE_GREYSCALE, + DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE }; enum DisplayRotation { @@ -185,6 +190,12 @@ class MicroBitDisplay : public MicroBitComponent */ void render(); + /** + * Renders the current image, and drops the fourth frame to allow for + * sensors that require the display to operate. + */ + void renderWithLightSense(); + /** * Translates a bit mask into a timer interrupt that gives the appearence of greyscale. */ @@ -473,7 +484,7 @@ public: /** * Sets the mode of the display. - * @param mode The mode to swap the display into. (can be either DISPLAY_MODE_GREYSCALE, or DISPLAY_MODE_NORMAL) + * @param mode The mode to swap the display into. (can be either DISPLAY_MODE_GREYSCALE, DISPLAY_MODE_BLACK_AND_WHITE, DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE) * * Example: * @code @@ -482,6 +493,12 @@ public: */ void setDisplayMode(DisplayMode mode); + /** + * Gets the mode of the display. + * @return the current mode of the display + */ + int getDisplayMode(); + /** * Fetches the current brightness of this display. * @return the brightness of this display, in the range 0..255. diff --git a/source/MicroBitDisplay.cpp b/source/MicroBitDisplay.cpp index 1ad22d2..0ef5014 100644 --- a/source/MicroBitDisplay.cpp +++ b/source/MicroBitDisplay.cpp @@ -34,7 +34,7 @@ MicroBitDisplay::MicroBitDisplay(uint16_t id, uint8_t x, uint8_t y) : this->width = x; this->height = y; this->strobeRow = 0; - this->strobeBitMsk = 0x20; + this->strobeBitMsk = MICROBIT_DISPLAY_ROW_RESET; this->rotation = MICROBIT_DISPLAY_ROTATION_0; this->greyscaleBitMsk = 0x01; this->timingCount = 0; @@ -58,6 +58,12 @@ void MicroBitDisplay::systemTick() if(!(uBit.flags & MICROBIT_FLAG_DISPLAY_RUNNING)) return; + if(mode == DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE) + { + renderWithLightSense(); + return; + } + // Move on to the next row. strobeBitMsk <<= 1; strobeRow++; @@ -65,7 +71,7 @@ void MicroBitDisplay::systemTick() //reset the row counts and bit mask when we have hit the max. if(strobeRow == MICROBIT_DISPLAY_ROW_COUNT){ strobeRow = 0; - strobeBitMsk = 0x20; + strobeBitMsk = MICROBIT_DISPLAY_ROW_RESET; } if(mode == DISPLAY_MODE_BLACK_AND_WHITE) @@ -146,6 +152,30 @@ void MicroBitDisplay::render() renderFinish(); } +void MicroBitDisplay::renderWithLightSense() +{ + //reset the row counts and bit mask when we have hit the max. + if(strobeRow == MICROBIT_DISPLAY_ROW_COUNT + 1) + { + + MicroBitEvent(id, MICROBIT_DISPLAY_EVT_LIGHT_SENSE); + + strobeRow = 0; + strobeBitMsk = MICROBIT_DISPLAY_ROW_RESET; + } + else + { + + render(); + this->animationUpdate(); + + // Move on to the next row. + strobeBitMsk <<= 1; + strobeRow++; + } + +} + void MicroBitDisplay::renderGreyscale() { int coldata = 0; @@ -883,7 +913,7 @@ int MicroBitDisplay::setBrightness(int b) /** * Sets the mode of the display. - * @param mode The mode to swap the display into. (can be either DISPLAY_MODE_GREYSCALE, or DISPLAY_MODE_NORMAL) + * @param mode The mode to swap the display into. (can be either DISPLAY_MODE_GREYSCALE, DISPLAY_MODE_BLACK_AND_WHITE, DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE) * * Example: * @code @@ -895,6 +925,15 @@ void MicroBitDisplay::setDisplayMode(DisplayMode mode) this->mode = mode; } +/** + * Gets the mode of the display. + * @return the current mode of the display + */ +int MicroBitDisplay::getDisplayMode() +{ + return this->mode; +} + /** * Fetches the current brightness of this display. * @return the brightness of this display, in the range 0..255. @@ -992,7 +1031,7 @@ void MicroBitDisplay::error(int statusCode) disable(); //relinquish PWMOut's control uint8_t strobeRow = 0; - uint8_t strobeBitMsk = 0x20; + uint8_t strobeBitMsk = MICROBIT_DISPLAY_ROW_RESET; //point to the font stored in Flash const unsigned char * fontLocation = MicroBitFont::defaultFont; @@ -1019,7 +1058,7 @@ void MicroBitDisplay::error(int statusCode) if(strobeRow == 3) { strobeRow = 0; - strobeBitMsk = 0x20; + strobeBitMsk = MICROBIT_DISPLAY_ROW_RESET; } // Calculate the bitpattern to write. From 6e316dc741a721ae2aeaeda22db0b31aba7f9896 Mon Sep 17 00:00:00 2001 From: James Devine Date: Fri, 29 Jan 2016 14:07:36 +0000 Subject: [PATCH 3/6] microbit: added accessor/mutator for systemTick This commit adds a mutator that dynamically reconfigures the systemTicker to call systemTick at a different period to the default. The accessor returns the current tick speed in milliseconds. The accessor is now also used in scheduler_tick to keep timing as accurate as possible. MICROBIT_DISPLAY_REFRESH_PERIOD has now been removed, and replaced with MICROBIT_DEFAULT_TICK_PERIOD. --- inc/MicroBit.h | 25 ++++++++++++++++++++++--- inc/MicroBitDisplay.h | 6 ------ source/MicroBit.cpp | 35 +++++++++++++++++++++++++++++++++-- source/MicroBitDisplay.cpp | 2 +- source/MicroBitFiber.cpp | 4 ++-- 5 files changed, 58 insertions(+), 14 deletions(-) diff --git a/inc/MicroBit.h b/inc/MicroBit.h index 135f15a..bb80f6b 100644 --- a/inc/MicroBit.h +++ b/inc/MicroBit.h @@ -46,12 +46,14 @@ #define MICROBIT_NAME_CODE_LETTERS 5 // Random number generator -#define NRF51822_RNG_ADDRESS 0x4000D000 +#define NRF51822_RNG_ADDRESS 0x4000D000 // mbed pin assignments of core components. -#define MICROBIT_PIN_SDA P0_30 -#define MICROBIT_PIN_SCL P0_0 +#define MICROBIT_PIN_SDA P0_30 +#define MICROBIT_PIN_SCL P0_0 + +#define MICROBIT_DEFAULT_TICK_PERIOD FIBER_TICK_PERIOD_MS /** * Class definition for a MicroBit device. @@ -74,6 +76,8 @@ class MicroBit // Periodic callback Ticker systemTicker; + int tickPeriod; + // I2C Interface MicroBitI2C i2c; @@ -259,6 +263,21 @@ class MicroBit */ int removeIdleComponent(MicroBitComponent *component); + + /* + * Reconfigures the ticker to the given speed in milliseconds. + * @param speedMs the speed in milliseconds + * @return MICROBIT_OK on success. MICROBIT_INVALID_PARAMETER is returned if speedUs < 1 + * + * @note this will also modify the value that is added to ticks in MiroBitFiber:scheduler_tick() + */ + int setTickPeriod(int speedMs); + + /* + * Returns the currently used tick speed in milliseconds + */ + int getTickPeriod(); + /** * Determine the time since this MicroBit was last reset. * diff --git a/inc/MicroBitDisplay.h b/inc/MicroBitDisplay.h index a96e497..cbaee86 100644 --- a/inc/MicroBitDisplay.h +++ b/inc/MicroBitDisplay.h @@ -1,12 +1,6 @@ #ifndef MICROBIT_DISPLAY_H #define MICROBIT_DISPLAY_H - -/** - * Core Configuration settings. - */ -#define MICROBIT_DISPLAY_REFRESH_PERIOD ((float)FIBER_TICK_PERIOD_MS / (float)1000) - /** * MessageBus Event Codes */ diff --git a/source/MicroBit.cpp b/source/MicroBit.cpp index e783c67..651d54a 100644 --- a/source/MicroBit.cpp +++ b/source/MicroBit.cpp @@ -1,4 +1,4 @@ -/* +/* * The underlying Nordic libraries that support BLE do not compile cleanly with the stringent GCC settings we employ * If we're compiling under GCC, then we suppress any warnings generated from this code (but not the rest of the DAL) * The ARM cc compiler is more tolerant. We don't test __GNUC__ here to detect GCC as ARMCC also typically sets this @@ -133,8 +133,10 @@ void MicroBit::init() // Seed our random number generator seedRandom(); + tickPeriod = MICROBIT_DEFAULT_TICK_PERIOD; + // Start refreshing the Matrix Display - systemTicker.attach(this, &MicroBit::systemTick, MICROBIT_DISPLAY_REFRESH_PERIOD); + systemTicker.attach_us(this, &MicroBit::systemTick, tickPeriod * 1000); // Register our compass calibration algorithm. MessageBus.listen(MICROBIT_ID_COMPASS, MICROBIT_COMPASS_EVT_CALIBRATE, this, &MicroBit::compassCalibrator, MESSAGE_BUS_LISTENER_IMMEDIATE); @@ -607,6 +609,35 @@ int MicroBit::removeIdleComponent(MicroBitComponent *component) return MICROBIT_OK; } +/* + * Reconfigures the ticker to the given speed in milliseconds. + * @param speedMs the speed in milliseconds + * @return MICROBIT_OK on success. MICROBIT_INVALID_PARAMETER is returned if speedUs < 1 + * + * @note this will also modify the value that is added to ticks in MiroBitFiber:scheduler_tick() + */ +int MicroBit::setTickPeriod(int speedMs) +{ + if(speedMs < 1) + return MICROBIT_INVALID_PARAMETER; + + uBit.systemTicker.detach(); + + uBit.systemTicker.attach_us(this, &MicroBit::systemTick, speedMs * 1000); + + tickPeriod = speedMs; + + return MICROBIT_OK; +} + +/* + * Returns the currently used tick speed in milliseconds + */ +int MicroBit::getTickPeriod() +{ + return tickPeriod; +} + /** * Determine the time since this MicroBit was last reset. * diff --git a/source/MicroBitDisplay.cpp b/source/MicroBitDisplay.cpp index 0ef5014..4303563 100644 --- a/source/MicroBitDisplay.cpp +++ b/source/MicroBitDisplay.cpp @@ -145,7 +145,7 @@ void MicroBitDisplay::render() //timer does not have enough resolution for brightness of 1. 23.53 us if(brightness != MICROBIT_DISPLAY_MAXIMUM_BRIGHTNESS && brightness > MICROBIT_DISPLAY_MINIMUM_BRIGHTNESS) - renderTimer.attach(this, &MicroBitDisplay::renderFinish, (((float)brightness) / ((float)MICROBIT_DISPLAY_MAXIMUM_BRIGHTNESS)) * (float)MICROBIT_DISPLAY_REFRESH_PERIOD); + renderTimer.attach_us(this, &MicroBitDisplay::renderFinish, (((brightness * 100) / (MICROBIT_DISPLAY_MAXIMUM_BRIGHTNESS)) * uBit.getTickPeriod())); //this will take around 23us to execute if(brightness <= MICROBIT_DISPLAY_MINIMUM_BRIGHTNESS) diff --git a/source/MicroBitFiber.cpp b/source/MicroBitFiber.cpp index aabea0f..bebe05a 100644 --- a/source/MicroBitFiber.cpp +++ b/source/MicroBitFiber.cpp @@ -181,8 +181,8 @@ void scheduler_tick() Fiber *t; // increment our real-time counter. - ticks += FIBER_TICK_PERIOD_MS; - + ticks += uBit.getTickPeriod(); + // Check the sleep queue, and wake up any fibers as necessary. while (f != NULL) { From 2049e630393173bf357762bb02da4f869776f204 Mon Sep 17 00:00:00 2001 From: James Devine Date: Fri, 29 Jan 2016 14:10:52 +0000 Subject: [PATCH 4/6] microbit: added MicroBitLightSensor Added a new class called MicroBitLightSensor which interleaves sensing with the display. This class takes advantage of the previous commits which add a dynamic system tick, and a new display mode for the display. A future optimisation would be for the display to handle the instantion of a light sensor when the display mode is changed! --- inc/MicroBit.h | 1 + inc/MicroBitLightSensor.h | 99 +++++++++++++++++++++++++ source/CMakeLists.txt | 1 + source/MicroBitLightSensor.cpp | 131 +++++++++++++++++++++++++++++++++ 4 files changed, 232 insertions(+) create mode 100644 inc/MicroBitLightSensor.h create mode 100644 source/MicroBitLightSensor.cpp diff --git a/inc/MicroBit.h b/inc/MicroBit.h index bb80f6b..0d4f8a5 100644 --- a/inc/MicroBit.h +++ b/inc/MicroBit.h @@ -24,6 +24,7 @@ #include "MicroBitCompass.h" #include "MicroBitAccelerometer.h" #include "MicroBitThermometer.h" +#include "MicroBitLightSensor.h" #include "MicroBitMultiButton.h" #include "MicroBitSerial.h" diff --git a/inc/MicroBitLightSensor.h b/inc/MicroBitLightSensor.h new file mode 100644 index 0000000..829c6a6 --- /dev/null +++ b/inc/MicroBitLightSensor.h @@ -0,0 +1,99 @@ +#ifndef MICROBIT_LIGHT_SENSOR_H +#define MICROBIT_LIGHT_SENSOR_H + +#include "mbed.h" +#include "MicroBitComponent.h" + +#define MICROBIT_LIGHT_SENSOR_CHAN_NUM 3 +#define MICROBIT_LIGHT_SENSOR_AN_SET_TIME 4000 +#define MICROBIT_LIGHT_SENSOR_TICK_PERIOD 5 + +/** + * Class definition for MicroBitLightSensor. + * + * This is an object that interleaves light sensing with uBit.display. + */ +class MicroBitLightSensor +{ + + //contains the results from each section of the display + int results[MICROBIT_LIGHT_SENSOR_CHAN_NUM] = { 0 }; + + //holds the current channel (also used to index the results array) + uint8_t chan; + + //a Timeout which triggers our analogReady() call + Timeout analogTrigger; + + //a pointer the currently sensed pin, represented as an AnalogIn + AnalogIn* sensePin; + + /** + * After the startSensing method has been called, this method will be called + * MICROBIT_LIGHT_SENSOR_AN_SET_TIME after. + * + * It will then read from the currently selected channel using the AnalogIn + * that was configured in the startSensing method. + */ + void analogReady(); + + /** + * Forcibly disables the AnalogIn, otherwise it will remain in possession + * of the GPIO channel it is using, meaning that the display will not be + * able to use a channel (COL). + * + * This is required as per PAN 3, details of which can be found here: + * + * https://www.nordicsemi.com/eng/nordic/download_resource/24634/5/88440387 + */ + void analogDisable(); + + /** + * The method that is invoked by sending MICROBIT_DISPLAY_EVT_LIGHT_SENSE + * using the id MICROBIT_ID_DISPLAY. + * + * If you want to manually trigger this method, you should use the event bus. + */ + void startSensing(MicroBitEvent); + + public: + + /** + * Constructor. + * Create a representation of the light sensor + */ + MicroBitLightSensor(); + + /** + * This method returns a summed average of the three sections of the display. + * + * A section is defined as: + * ___________________ + * | 1 | | 2 | | 3 | + * |___|___|___|___|___| + * | | | | | | + * |___|___|___|___|___| + * | 2 | | 3 | | 1 | + * |___|___|___|___|___| + * | | | | | | + * |___|___|___|___|___| + * | 3 | | 1 | | 2 | + * |___|___|___|___|___| + * + * Where each number represents a different section on the 5 x 5 matrix display. + * + * @note currently values are inverted to how one would think: + * - Lower is brighter + * - Higher is darker + * TODO: Normalise the returned values into an SI unit! + */ + int read(); + + /** + * The destructor restores the default Display Mode and tick speed, and also + * removes the listener from the MessageBus. + */ + ~MicroBitLightSensor(); +}; + +#endif diff --git a/source/CMakeLists.txt b/source/CMakeLists.txt index 615e6fd..0fddce0 100755 --- a/source/CMakeLists.txt +++ b/source/CMakeLists.txt @@ -29,6 +29,7 @@ set(YOTTA_AUTO_MICROBIT-DAL_CPP_FILES "MicroBitSerial.cpp" "MicroBitHeapAllocator.cpp" "MicroBitListener.cpp" + "MicroBitLightSensor.cpp" "RefCounted.cpp" "MemberFunctionCallback.cpp" "ble-services/MicroBitBLEManager.cpp" diff --git a/source/MicroBitLightSensor.cpp b/source/MicroBitLightSensor.cpp new file mode 100644 index 0000000..fb83c74 --- /dev/null +++ b/source/MicroBitLightSensor.cpp @@ -0,0 +1,131 @@ +/** + * Class definition for MicroBitLightSensor. + * + * This is an object that interleaves light sensing with uBit.display. + */ + +#include "MicroBit.h" + +/** + * After the startSensing method has been called, this method will be called + * MICROBIT_LIGHT_SENSOR_AN_SET_TIME after. + * + * It will then read from the currently selected channel using the AnalogIn + * that was configured in the startSensing method. + */ +void MicroBitLightSensor::analogReady() +{ + this->results[chan] = this->sensePin->read_u16(); + + analogDisable(); + + DigitalOut((PinName)(MICROBIT_DISPLAY_COLUMN_START + chan)).write(1); + + chan++; + + chan = chan % MICROBIT_LIGHT_SENSOR_CHAN_NUM; +} + +/** + * Forcibly disables the AnalogIn, otherwise it will remain in possession + * of the GPIO channel it is using, meaning that the display will not be + * able to use a channel (COL). + * + * This is required as per PAN 3, details of which can be found here: + * + * https://www.nordicsemi.com/eng/nordic/download_resource/24634/5/88440387 + */ +void MicroBitLightSensor::analogDisable() +{ + NRF_ADC->ENABLE = ADC_ENABLE_ENABLE_Disabled; + + NRF_ADC->CONFIG = (ADC_CONFIG_RES_8bit << ADC_CONFIG_RES_Pos) | + (ADC_CONFIG_INPSEL_SupplyTwoThirdsPrescaling << ADC_CONFIG_INPSEL_Pos) | + (ADC_CONFIG_REFSEL_VBG << ADC_CONFIG_REFSEL_Pos) | + (ADC_CONFIG_PSEL_Disabled << ADC_CONFIG_PSEL_Pos) | + (ADC_CONFIG_EXTREFSEL_None << ADC_CONFIG_EXTREFSEL_Pos); +} + +/** + * The method that is invoked by sending MICROBIT_DISPLAY_EVT_LIGHT_SENSE + * using the id MICROBIT_ID_DISPLAY. + * + * If you want to manually trigger this method, you should use the event bus. + * + * @note This is currently too churny, and allocates a lot of stuff on the stack + * however, this makes this chunk of code platform agnostic in mbed land. + */ +void MicroBitLightSensor::startSensing(MicroBitEvent) +{ + for(int rowCount = 0; rowCount < MICROBIT_DISPLAY_ROW_COUNT; rowCount++) + DigitalOut((PinName)(MICROBIT_DISPLAY_ROW_START + rowCount)).write(0); + + PinName currentPin = (PinName)(MICROBIT_DISPLAY_COLUMN_START + chan); + + DigitalOut(currentPin).write(1); + + DigitalIn(currentPin, PullNone).~DigitalIn(); + + if(this->sensePin != NULL) + delete this->sensePin; + + this->sensePin = new AnalogIn(currentPin); + + analogTrigger.attach_us(this, &MicroBitLightSensor::analogReady, MICROBIT_LIGHT_SENSOR_AN_SET_TIME); +} + +/** + * Constructor. + * Create a representation of the light sensor + */ +MicroBitLightSensor::MicroBitLightSensor() : analogTrigger() +{ + this->chan = 0; + + uBit.MessageBus.listen(MICROBIT_ID_DISPLAY, MICROBIT_DISPLAY_EVT_LIGHT_SENSE, this, &MicroBitLightSensor::startSensing, MESSAGE_BUS_LISTENER_IMMEDIATE); + + this->sensePin = NULL; +} + +/** + * This method returns a summed average of the three sections of the display. + * + * A section is defined as: + * ___________________ + * | 1 | | 2 | | 3 | + * |___|___|___|___|___| + * | | | | | | + * |___|___|___|___|___| + * | 2 | | 3 | | 1 | + * |___|___|___|___|___| + * | | | | | | + * |___|___|___|___|___| + * | 3 | | 1 | | 2 | + * |___|___|___|___|___| + * + * Where each number represents a different section on the 5 x 5 matrix display. + * + * @note currently values are inverted to how one would think: + * - Lower is brighter + * - Higher is darker + * TODO: Normalise the returned values into an SI unit! + */ +int MicroBitLightSensor::read() +{ + int sum = 0; + + for(int i = 0; i < MICROBIT_LIGHT_SENSOR_CHAN_NUM; i++) + sum += results[i]; + + return sum/MICROBIT_LIGHT_SENSOR_CHAN_NUM; +} + + +/** + * The destructor restores the default Display Mode and tick speed, and also + * removes the listener from the MessageBus. + */ +MicroBitLightSensor::~MicroBitLightSensor() +{ + uBit.MessageBus.ignore(MICROBIT_ID_DISPLAY, MICROBIT_DISPLAY_EVT_LIGHT_SENSE, this, &MicroBitLightSensor::startSensing); +} From 6b0e9cf4894954c4358f2989fb8a426ea8549f8b Mon Sep 17 00:00:00 2001 From: James Devine Date: Fri, 29 Jan 2016 14:13:41 +0000 Subject: [PATCH 5/6] microbit: integrated MicroBitLightSensor with MicroBitDisplay Previously, to light sense a user would have to configure a MicroBitLightSensor instance themselves, and flip the display mode manually. This is difficult in languages that target our API. This commit resolves that by adding a new method readLightLevel which flips the display mode, and instantiates a light sensor. When changing the mode, the tickSpeed is also modified to reduce artefacts on the display. --- inc/MicroBitDisplay.h | 16 ++++++++++++++ source/MicroBitDisplay.cpp | 43 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+) diff --git a/inc/MicroBitDisplay.h b/inc/MicroBitDisplay.h index cbaee86..7847058 100644 --- a/inc/MicroBitDisplay.h +++ b/inc/MicroBitDisplay.h @@ -160,6 +160,9 @@ class MicroBitDisplay : public MicroBitComponent // The number of pixels the image is shifted on the display in each quantum. int8_t scrollingImageStride; + // A pointer to an instance of light sensor, if in use + MicroBitLightSensor* lightSensor; + // Flag to indicate if image has been rendered to screen yet (or not) bool scrollingImageRendered; @@ -574,6 +577,19 @@ public: */ MicroBitImage screenShot(); + /** + * Constructs an instance of a MicroBitLightSensor if not already configured + * and sets the display mode to DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE. + * + * This also changes the tickPeriod to MICROBIT_LIGHT_SENSOR_TICK_SPEED so + * that the display does not suffer from artifacts. + * + * @note this will return 0 on the first call to this method, a light reading + * will be available after the display has activated the light sensor for the + * first time. + */ + int readLightLevel(); + /** * Destructor for MicroBitDisplay, so that we deregister ourselves as a systemComponent */ diff --git a/source/MicroBitDisplay.cpp b/source/MicroBitDisplay.cpp index 4303563..48c93d2 100644 --- a/source/MicroBitDisplay.cpp +++ b/source/MicroBitDisplay.cpp @@ -44,6 +44,8 @@ MicroBitDisplay::MicroBitDisplay(uint16_t id, uint8_t x, uint8_t y) : this->mode = DISPLAY_MODE_BLACK_AND_WHITE; this->animationMode = ANIMATION_MODE_NONE; + this->lightSensor = NULL; + uBit.flags |= MICROBIT_FLAG_DISPLAY_RUNNING; } @@ -922,6 +924,25 @@ int MicroBitDisplay::setBrightness(int b) */ void MicroBitDisplay::setDisplayMode(DisplayMode mode) { + if(mode == DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE) + { + //to reduce the artifacts on the display - increase the tick + if(uBit.getTickPeriod() != MICROBIT_LIGHT_SENSOR_TICK_PERIOD) + uBit.setTickPeriod(MICROBIT_LIGHT_SENSOR_TICK_PERIOD); + } + + if(this->mode == DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE && mode != DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE) + { + + //if we previously were in light sense mode - return to our default. + if(uBit.getTickPeriod() != MICROBIT_DEFAULT_TICK_PERIOD) + uBit.setTickPeriod(MICROBIT_DEFAULT_TICK_PERIOD); + + delete this->lightSensor; + + this->lightSensor = NULL; + } + this->mode = mode; } @@ -1126,6 +1147,28 @@ MicroBitImage MicroBitDisplay::screenShot() return image.crop(0,0,MICROBIT_DISPLAY_WIDTH,MICROBIT_DISPLAY_HEIGHT); } +/** + * Constructs an instance of a MicroBitLightSensor if not already configured + * and sets the display mode to DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE. + * + * This also changes the tickPeriod to MICROBIT_LIGHT_SENSOR_TICK_SPEED so + * that the display does not suffer from artifacts. + * + * @note this will return 0 on the first call to this method, a light reading + * will be available after the display has activated the light sensor for the + * first time. + */ +int MicroBitDisplay::readLightLevel() +{ + if(mode != DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE) + { + setDisplayMode(DISPLAY_MODE_BLACK_AND_WHITE_LIGHT_SENSE); + this->lightSensor = new MicroBitLightSensor(); + } + + return this->lightSensor->read(); +} + /** * Destructor for MicroBitDisplay, so that we deregister ourselves as a systemComponent */ From 8150b2ac67cacef5e7330cacf131cd62d9fc6da5 Mon Sep 17 00:00:00 2001 From: James Devine Date: Mon, 1 Feb 2016 21:46:15 +0000 Subject: [PATCH 6/6] microbit: modified as per suggestions * This commit fixes an exposed member variable that was not intended to be public 'tickPeriod' * normalised the light level to return values between 0 - 100 --- inc/MicroBit.h | 4 ++-- inc/MicroBitLightSensor.h | 13 +++++++++---- source/MicroBitLightSensor.cpp | 22 +++++++++++++++++----- 3 files changed, 28 insertions(+), 11 deletions(-) diff --git a/inc/MicroBit.h b/inc/MicroBit.h index 0d4f8a5..f800bad 100644 --- a/inc/MicroBit.h +++ b/inc/MicroBit.h @@ -68,6 +68,8 @@ class MicroBit void compassCalibrator(MicroBitEvent e); uint32_t randomValue; + //the current tick period in MS + int tickPeriod; public: @@ -77,8 +79,6 @@ class MicroBit // Periodic callback Ticker systemTicker; - int tickPeriod; - // I2C Interface MicroBitI2C i2c; diff --git a/inc/MicroBitLightSensor.h b/inc/MicroBitLightSensor.h index 829c6a6..a149efa 100644 --- a/inc/MicroBitLightSensor.h +++ b/inc/MicroBitLightSensor.h @@ -8,6 +8,9 @@ #define MICROBIT_LIGHT_SENSOR_AN_SET_TIME 4000 #define MICROBIT_LIGHT_SENSOR_TICK_PERIOD 5 +#define MICROBIT_LIGHT_SENSOR_MAX_VALUE 338 +#define MICROBIT_LIGHT_SENSOR_MIN_VALUE 75 + /** * Class definition for MicroBitLightSensor. * @@ -82,10 +85,12 @@ class MicroBitLightSensor * * Where each number represents a different section on the 5 x 5 matrix display. * - * @note currently values are inverted to how one would think: - * - Lower is brighter - * - Higher is darker - * TODO: Normalise the returned values into an SI unit! + * @return returns a value in the range 0 - 100 where 0 is dark, and 100 + * is very bright + * + * @note currently returns a value in the range 0 - 100 where 0 is dark, and 100 + * is very bright perhaps we should normalise the returned values into an SI unit! + * TODO. */ int read(); diff --git a/source/MicroBitLightSensor.cpp b/source/MicroBitLightSensor.cpp index fb83c74..efe29ce 100644 --- a/source/MicroBitLightSensor.cpp +++ b/source/MicroBitLightSensor.cpp @@ -105,10 +105,12 @@ MicroBitLightSensor::MicroBitLightSensor() : analogTrigger() * * Where each number represents a different section on the 5 x 5 matrix display. * - * @note currently values are inverted to how one would think: - * - Lower is brighter - * - Higher is darker - * TODO: Normalise the returned values into an SI unit! + * @return returns a value in the range 0 - 100 where 0 is dark, and 100 + * is very bright + * + * @note currently returns a value in the range 0 - 100 where 0 is dark, and 100 + * is very bright perhaps we should normalise the returned values into an SI unit! + * TODO. */ int MicroBitLightSensor::read() { @@ -117,7 +119,17 @@ int MicroBitLightSensor::read() for(int i = 0; i < MICROBIT_LIGHT_SENSOR_CHAN_NUM; i++) sum += results[i]; - return sum/MICROBIT_LIGHT_SENSOR_CHAN_NUM; + int average = sum / MICROBIT_LIGHT_SENSOR_CHAN_NUM; + + average = min(average, MICROBIT_LIGHT_SENSOR_MAX_VALUE); + + average = max(average, MICROBIT_LIGHT_SENSOR_MIN_VALUE); + + int inverted = (MICROBIT_LIGHT_SENSOR_MAX_VALUE - average) + MICROBIT_LIGHT_SENSOR_MIN_VALUE; + + int normalised = ((inverted - MICROBIT_LIGHT_SENSOR_MIN_VALUE) * 100) / (MICROBIT_LIGHT_SENSOR_MAX_VALUE - MICROBIT_LIGHT_SENSOR_MIN_VALUE); + + return normalised; }