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microbit-dal/source/MicroBit.cpp

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/*
* 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
* as a compatability option, but does not support the options used...
*/
#if !defined(__arm)
#pragma GCC diagnostic ignored "-Wunused-function"
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif
#include "MicroBit.h"
#include "nrf_soc.h"
/*
* Return to our predefined compiler settings.
*/
#if !defined(__arm)
#pragma GCC diagnostic pop
#endif
/**
* custom function for panic for malloc & new due to scoping issue.
*/
void panic(int statusCode)
{
uBit.panic(statusCode);
}
/**
* Callback that performs a hard reset when a BLE GAP disconnect occurs.
* Only used when an explicit reset is invoked locally whilst a BLE connection is in progress.
* This allows for a clean diconnect of the BLE connection before resetting.
*/
void bleDisconnectionResetCallback(const Gap::DisconnectionCallbackParams_t *)
{
NVIC_SystemReset();
}
/**
* Perform a hard reset of the micro:bit.
* If BLE connected, then try to signal a disconnect first
*/
void
microbit_reset()
{
if(uBit.ble && uBit.ble->getGapState().connected) {
uBit.ble->onDisconnection(bleDisconnectionResetCallback);
uBit.ble->gap().disconnect(Gap::REMOTE_USER_TERMINATED_CONNECTION);
// We should be reset by the disconnection callback, so we wait to
// allow that to happen. If it doesn't happen, then we fall through to the
// hard rest here. (For example there is a race condition where
// the remote device disconnects between us testing the connection
// state and re-setting the disconnection callback).
uBit.sleep(1000);
}
NVIC_SystemReset();
}
void bleDisconnectionCallback(const Gap::DisconnectionCallbackParams_t *)
{
uBit.ble->startAdvertising();
}
/**
* Constructor.
* Create a representation of a MicroBit device as a global singleton.
* @param messageBus callback function to receive MicroBitMessageBus events.
*
* Exposed objects:
* @code
* uBit.systemTicker; //the Ticker callback that performs routines like updating the display.
* uBit.MessageBus; //The message bus where events are fired.
* uBit.display; //The display object for the LED matrix.
* uBit.buttonA; //The buttonA object for button a.
* uBit.buttonB; //The buttonB object for button b.
* uBit.buttonAB; //The buttonAB object for button a+b multi press.
* uBit.resetButton; //The resetButton used for soft resets.
* uBit.accelerometer; //The object that represents the inbuilt accelerometer
* uBit.compass; //The object that represents the inbuilt compass(magnetometer)
* uBit.io.P*; //Where P* is P0 to P16, P19 & P20 on the edge connector
* @endcode
*/
MicroBit::MicroBit() :
flags(0x00),
i2c(MICROBIT_PIN_SDA, MICROBIT_PIN_SCL),
serial(USBTX, USBRX),
MessageBus(),
display(MICROBIT_ID_DISPLAY, MICROBIT_DISPLAY_WIDTH, MICROBIT_DISPLAY_HEIGHT),
buttonA(MICROBIT_ID_BUTTON_A,MICROBIT_PIN_BUTTON_A, MICROBIT_BUTTON_SIMPLE_EVENTS),
buttonB(MICROBIT_ID_BUTTON_B,MICROBIT_PIN_BUTTON_B, MICROBIT_BUTTON_SIMPLE_EVENTS),
buttonAB(MICROBIT_ID_BUTTON_AB,MICROBIT_ID_BUTTON_A,MICROBIT_ID_BUTTON_B),
accelerometer(MICROBIT_ID_ACCELEROMETER, MMA8653_DEFAULT_ADDR),
compass(MICROBIT_ID_COMPASS, MAG3110_DEFAULT_ADDR),
thermometer(MICROBIT_ID_THERMOMETER),
io(MICROBIT_ID_IO_P0,MICROBIT_ID_IO_P1,MICROBIT_ID_IO_P2,
MICROBIT_ID_IO_P3,MICROBIT_ID_IO_P4,MICROBIT_ID_IO_P5,
MICROBIT_ID_IO_P6,MICROBIT_ID_IO_P7,MICROBIT_ID_IO_P8,
MICROBIT_ID_IO_P9,MICROBIT_ID_IO_P10,MICROBIT_ID_IO_P11,
MICROBIT_ID_IO_P12,MICROBIT_ID_IO_P13,MICROBIT_ID_IO_P14,
MICROBIT_ID_IO_P15,MICROBIT_ID_IO_P16,MICROBIT_ID_IO_P19,
MICROBIT_ID_IO_P20),
bleManager(),
radio(MICROBIT_ID_RADIO),
ble(NULL)
{
}
/**
* Post constructor initialisation method.
* After *MUCH* pain, it's noted that the BLE stack can't be brought up in a
* static context, so we bring it up here rather than in the constructor.
* n.b. This method *must* be called in main() or later, not before.
*
* Example:
* @code
* uBit.init();
* @endcode
*/
void MicroBit::init()
{
//add the display to the systemComponent array
addSystemComponent(&uBit.display);
//add the compass and accelerometer to the idle array
addIdleComponent(&uBit.accelerometer);
addIdleComponent(&uBit.compass);
addIdleComponent(&uBit.MessageBus);
// Seed our random number generator
seedRandom();
tickPeriod = MICROBIT_DEFAULT_TICK_PERIOD;
// Start refreshing the Matrix Display
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);
}
/**
* Performs a simple game that in parallel, calibrates the compass.
* This function is executed automatically when the user requests a compass bearing, and compass calibration is required.
* This function is, by design, synchronous and only returns once calibration is complete.
*/
void MicroBit::compassCalibrator(MicroBitEvent)
{
struct Point
{
uint8_t x;
uint8_t y;
uint8_t on;
};
const int PERIMETER_POINTS = 12;
const int PIXEL1_THRESHOLD = 200;
const int PIXEL2_THRESHOLD = 800;
Matrix4 X(PERIMETER_POINTS, 4);
Point perimeter[PERIMETER_POINTS] = {{1,0,0}, {2,0,0}, {3,0,0}, {4,1,0}, {4,2,0}, {4,3,0}, {3,4,0}, {2,4,0}, {1,4,0}, {0,3,0}, {0,2,0}, {0,1,0}};
Point cursor = {2,2,0};
MicroBitImage img(5,5);
MicroBitImage smiley("0,255,0,255,0\n0,255,0,255,0\n0,0,0,0,0\n255,0,0,0,255\n0,255,255,255,0\n");
int samples = 0;
// Firstly, we need to take over the display. Ensure all active animations are paused.
display.stopAnimation();
display.scrollAsync("DRAW A CIRCLE");
for (int i=0; i<110; i++)
{
if (buttonA.isPressed() || buttonB.isPressed())
{
break;
}
sleep(100);
}
display.stopAnimation();
display.clear();
while(samples < PERIMETER_POINTS)
{
// update our model of the flash status of the user controlled pixel.
cursor.on = (cursor.on + 1) % 4;
// take a snapshot of the current accelerometer data.
int x = uBit.accelerometer.getX();
int y = uBit.accelerometer.getY();
// Deterine the position of the user controlled pixel on the screen.
if (x < -PIXEL2_THRESHOLD)
cursor.x = 0;
else if (x < -PIXEL1_THRESHOLD)
cursor.x = 1;
else if (x > PIXEL2_THRESHOLD)
cursor.x = 4;
else if (x > PIXEL1_THRESHOLD)
cursor.x = 3;
else
cursor.x = 2;
if (y < -PIXEL2_THRESHOLD)
cursor.y = 0;
else if (y < -PIXEL1_THRESHOLD)
cursor.y = 1;
else if (y > PIXEL2_THRESHOLD)
cursor.y = 4;
else if (y > PIXEL1_THRESHOLD)
cursor.y = 3;
else
cursor.y = 2;
img.clear();
// Turn on any pixels that have been visited.
for (int i=0; i<PERIMETER_POINTS; i++)
if (perimeter[i].on)
img.setPixelValue(perimeter[i].x, perimeter[i].y, 255);
// Update the pixel at the users position.
img.setPixelValue(cursor.x, cursor.y, 255);
// Update the buffer to the screen.
uBit.display.image.paste(img,0,0,0);
// test if we need to update the state at the users position.
for (int i=0; i<PERIMETER_POINTS; i++)
{
if (cursor.x == perimeter[i].x && cursor.y == perimeter[i].y && !perimeter[i].on)
{
// Record the sample data for later processing...
X.set(samples, 0, compass.getX(RAW));
X.set(samples, 1, compass.getY(RAW));
X.set(samples, 2, compass.getZ(RAW));
X.set(samples, 3, 1);
// Record that this pixel has been visited.
perimeter[i].on = 1;
samples++;
}
}
uBit.sleep(100);
}
// We have enough sample data to make a fairly accurate calibration.
// We use a Least Mean Squares approximation, as detailed in Freescale application note AN2426.
// Firstly, calculate the square of each sample.
Matrix4 Y(X.height(), 1);
for (int i = 0; i < X.height(); i++)
{
float v = X.get(i, 0)*X.get(i, 0) + X.get(i, 1)*X.get(i, 1) + X.get(i, 2)*X.get(i, 2);
Y.set(i, 0, v);
}
// Now perform a Least Squares Approximation.
Matrix4 Alpha = X.multiplyT(X).invert();
Matrix4 Gamma = X.multiplyT(Y);
Matrix4 Beta = Alpha.multiply(Gamma);
// The result contains the approximate zero point of each axis, but doubled.
// Halve each sample, and record this as the compass calibration data.
CompassSample cal ((int)(Beta.get(0,0) / 2), (int)(Beta.get(1,0) / 2), (int)(Beta.get(2,0) / 2));
compass.setCalibration(cal);
// Show a smiley to indicate that we're done, and continue on with the user program.
display.clear();
display.print(smiley, 0, 0, 0, 1500);
display.clear();
}
/**
* Return the friendly name for this device.
*
* @return A string representing the friendly name of this device.
*/
ManagedString MicroBit::getName()
{
char nameBuffer[MICROBIT_NAME_LENGTH];
const uint8_t codebook[MICROBIT_NAME_LENGTH][MICROBIT_NAME_CODE_LETTERS] =
{
{'z', 'v', 'g', 'p', 't'},
{'u', 'o', 'i', 'e', 'a'},
{'z', 'v', 'g', 'p', 't'},
{'u', 'o', 'i', 'e', 'a'},
{'z', 'v', 'g', 'p', 't'}
};
// We count right to left, so create a pointer to the end of the buffer.
char *name = nameBuffer;
name += MICROBIT_NAME_LENGTH;
// Derive our name from the nrf51822's unique ID.
uint32_t n = NRF_FICR->DEVICEID[1];
int ld = 1;
int d = MICROBIT_NAME_CODE_LETTERS;
int h;
for (int i=0; i<MICROBIT_NAME_LENGTH;i++)
{
h = (n % d) / ld;
n -= h;
d *= MICROBIT_NAME_CODE_LETTERS;
ld *= MICROBIT_NAME_CODE_LETTERS;
*--name = codebook[i][h];
}
return ManagedString(nameBuffer, MICROBIT_NAME_LENGTH);
}
/**
* Return the serial number of this device.
*
* @return A string representing the serial number of this device.
*/
ManagedString MicroBit::getSerial()
{
// We take to 16 bit numbers here, as we want the full range of ID bits, but don't want negative numbers...
int n1 = NRF_FICR->DEVICEID[1] & 0xffff;
int n2 = (NRF_FICR->DEVICEID[1] >> 16) & 0xffff;
// Simply concat the two numbers.
ManagedString s1 = ManagedString(n1);
ManagedString s2 = ManagedString(n2);
return s1 + s2;
}
/**
* Will reset the micro:bit when called.
*
* Example:
* @code
* uBit.reset();
* @endcode
*/
void MicroBit::reset()
{
microbit_reset();
}
/**
* Delay for the given amount of time.
* If the scheduler is running, this will deschedule the current fiber and perform
* a power efficent, concurrent sleep operation.
* If the scheduler is disabled or we're running in an interrupt context, this
* will revert to a busy wait.
*
* @note Values of below below the scheduling period (typical 6ms) tend to lose resolution.
*
* @param milliseconds the amount of time, in ms, to wait for. This number cannot be negative.
* @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER milliseconds is less than zero.
*
* Example:
* @code
* uBit.sleep(20); //sleep for 20ms
* @endcode
*/
int MicroBit::sleep(int milliseconds)
{
//sanity check, we can't time travel... (yet?)
if(milliseconds < 0)
return MICROBIT_INVALID_PARAMETER;
if (flags & MICROBIT_FLAG_SCHEDULER_RUNNING)
fiber_sleep(milliseconds);
else
wait_ms(milliseconds);
return MICROBIT_OK;
}
/**
* Generate a random number in the given range.
* We use a simple Galois LFSR random number generator here,
* as a Galois LFSR is sufficient for our applications, and much more lightweight
* than the hardware random number generator built int the processor, which takes
* a long time and uses a lot of energy.
*
* KIDS: You shouldn't use this is the real world to generte cryptographic keys though...
* have a think why not. :-)
*
* @param max the upper range to generate a number for. This number cannot be negative
* @return A random, natural number between 0 and the max-1. Or MICROBIT_INVALID_VALUE (defined in ErrorNo.h) if max is <= 0.
*
* Example:
* @code
* uBit.random(200); //a number between 0 and 199
* @endcode
*/
int MicroBit::random(int max)
{
uint32_t m, result;
//return MICROBIT_INVALID_VALUE if max is <= 0...
if(max <= 0)
return MICROBIT_INVALID_PARAMETER;
// Our maximum return value is actually one less than passed
max--;
do {
m = (uint32_t)max;
result = 0;
do {
// Cycle the LFSR (Linear Feedback Shift Register).
// We use an optimal sequence with a period of 2^32-1, as defined by Bruce Schneier here (a true legend in the field!),
// For those interested, it's documented in his paper:
// "Pseudo-Random Sequence Generator for 32-Bit CPUs: A fast, machine-independent generator for 32-bit Microprocessors"
// https://www.schneier.com/paper-pseudorandom-sequence.html
uint32_t rnd = randomValue;
rnd = ((((rnd >> 31)
^ (rnd >> 6)
^ (rnd >> 4)
^ (rnd >> 2)
^ (rnd >> 1)
^ rnd)
& 0x0000001)
<< 31 )
| (rnd >> 1);
randomValue = rnd;
result = ((result << 1) | (rnd & 0x00000001));
} while(m >>= 1);
} while (result > (uint32_t)max);
return result;
}
/**
* Seed our a random number generator (RNG).
* We use the NRF51822 in built cryptographic random number generator to seed a Galois LFSR.
* We do this as the hardware RNG is relatively high power, and use the the BLE stack internally,
* with a less than optimal application interface. A Galois LFSR is sufficient for our
* applications, and much more lightweight.
*/
void MicroBit::seedRandom()
{
randomValue = 0;
if(uBit.ble)
{
// If Bluetooth is enabled, we need to go through the Nordic software to safely do this.
uint32_t result = sd_rand_application_vector_get((uint8_t*)&randomValue, sizeof(randomValue));
// If we couldn't get the random bytes then at least make the seed non-zero.
if (result != NRF_SUCCESS)
randomValue = 0xBBC5EED;
}
else
{
// Othwerwise we can access the hardware RNG directly.
// Start the Random number generator. No need to leave it running... I hope. :-)
NRF_RNG->TASKS_START = 1;
for(int i = 0; i < 4; i++)
{
// Clear the VALRDY EVENT
NRF_RNG->EVENTS_VALRDY = 0;
// Wait for a number ot be generated.
while(NRF_RNG->EVENTS_VALRDY == 0);
randomValue = (randomValue << 8) | ((int) NRF_RNG->VALUE);
}
// Disable the generator to save power.
NRF_RNG->TASKS_STOP = 1;
}
}
/**
* Seed our pseudo random number generator (PRNG) using the given 32-bit value.
*/
void MicroBit::seedRandom(uint32_t seed)
{
randomValue = seed;
}
/**
* Periodic callback. Used by MicroBitDisplay, FiberScheduler and buttons.
*/
void MicroBit::systemTick()
{
// Scheduler callback. We do this here just as a single timer is more efficient. :-)
if (uBit.flags & MICROBIT_FLAG_SCHEDULER_RUNNING)
scheduler_tick();
//work out if any idle components need processing, if so prioritise the idle thread
for(int i = 0; i < MICROBIT_IDLE_COMPONENTS; i++)
if(idleThreadComponents[i] != NULL && idleThreadComponents[i]->isIdleCallbackNeeded())
{
fiber_flags |= MICROBIT_FLAG_DATA_READY;
break;
}
//update any components in the systemComponents array
for(int i = 0; i < MICROBIT_SYSTEM_COMPONENTS; i++)
if(systemTickComponents[i] != NULL)
systemTickComponents[i]->systemTick();
}
/**
* System tasks to be executed by the idle thread when the Micro:Bit isn't busy or when data needs to be read.
*/
void MicroBit::systemTasks()
{
//call the idleTick member function indiscriminately
for(int i = 0; i < MICROBIT_IDLE_COMPONENTS; i++)
if(idleThreadComponents[i] != NULL)
idleThreadComponents[i]->idleTick();
fiber_flags &= ~MICROBIT_FLAG_DATA_READY;
}
/**
* add a component to the array of components which invocate the systemTick member function during a systemTick
* @param component The component to add.
* @return MICROBIT_OK on success. MICROBIT_NO_RESOURCES is returned if further components cannot be supported.
* @note this will be converted into a dynamic list of components
*/
int MicroBit::addSystemComponent(MicroBitComponent *component)
{
int i = 0;
while(systemTickComponents[i] != NULL && i < MICROBIT_SYSTEM_COMPONENTS)
i++;
if(i == MICROBIT_SYSTEM_COMPONENTS)
return MICROBIT_NO_RESOURCES;
systemTickComponents[i] = component;
return MICROBIT_OK;
}
/**
* remove a component from the array of components
* @param component The component to remove.
* @return MICROBIT_OK on success. MICROBIT_INVALID_PARAMTER is returned if the given component has not been previous added.
* @note this will be converted into a dynamic list of components
*/
int MicroBit::removeSystemComponent(MicroBitComponent *component)
{
int i = 0;
while(systemTickComponents[i] != component && i < MICROBIT_SYSTEM_COMPONENTS)
i++;
if(i == MICROBIT_SYSTEM_COMPONENTS)
return MICROBIT_INVALID_PARAMETER;
systemTickComponents[i] = NULL;
return MICROBIT_OK;
}
/**
* add a component to the array of components which invocate the systemTick member function during a systemTick
* @param component The component to add.
* @return MICROBIT_OK on success. MICROBIT_NO_RESOURCES is returned if further components cannot be supported.
* @note this will be converted into a dynamic list of components
*/
int MicroBit::addIdleComponent(MicroBitComponent *component)
{
int i = 0;
while(idleThreadComponents[i] != NULL && i < MICROBIT_IDLE_COMPONENTS)
i++;
if(i == MICROBIT_IDLE_COMPONENTS)
return MICROBIT_NO_RESOURCES;
idleThreadComponents[i] = component;
return MICROBIT_OK;
}
/**
* remove a component from the array of components
* @param component The component to remove.
* @return MICROBIT_OK on success. MICROBIT_INVALID_PARAMTER is returned if the given component has not been previous added.
* @note this will be converted into a dynamic list of components
*/
int MicroBit::removeIdleComponent(MicroBitComponent *component)
{
int i = 0;
while(idleThreadComponents[i] != component && i < MICROBIT_IDLE_COMPONENTS)
i++;
if(i == MICROBIT_IDLE_COMPONENTS)
return MICROBIT_INVALID_PARAMETER;
idleThreadComponents[i] = NULL;
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.
*
* @return The time since the last reset, in milliseconds. This will result in overflow after 1.6 months.
* TODO: handle overflow case.
*/
unsigned long MicroBit::systemTime()
{
return ticks;
}
/**
* Determine the version of the micro:bit runtime currently in use.
*
* @return A textual description of the currentlt executing micro:bit runtime.
* TODO: handle overflow case.
*/
const char *MicroBit::systemVersion()
{
return MICROBIT_DAL_VERSION;
}
/**
* Triggers a microbit panic where an infinite loop will occur swapping between the panicFace and statusCode if provided.
*
* @param statusCode the status code of the associated error. Status codes must be in the range 0-255.
*/
void MicroBit::panic(int statusCode)
{
//show error and enter infinite while
uBit.display.error(statusCode);
}
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