Merge pull request #87 from lancaster-university/broadcast-radio

Adding Multicast peer-to-peer radio support MicroBitRadio!
This commit is contained in:
James Devine 2016-02-01 21:50:54 +00:00
commit 97c49d3279
13 changed files with 1007 additions and 6 deletions

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@ -68,4 +68,27 @@
#define MES_DEVICE_INCOMING_MESSAGE 8
#define MES_DPAD_CONTROLLER_ID 1104
#define MES_DPAD_BUTTON_A_DOWN 1
#define MES_DPAD_BUTTON_A_UP 2
#define MES_DPAD_BUTTON_B_DOWN 3
#define MES_DPAD_BUTTON_B_UP 4
#define MES_DPAD_BUTTON_C_DOWN 5
#define MES_DPAD_BUTTON_C_UP 6
#define MES_DPAD_BUTTON_D_DOWN 7
#define MES_DPAD_BUTTON_D_UP 8
#define MES_DPAD_BUTTON_1_DOWN 9
#define MES_DPAD_BUTTON_1_UP 10
#define MES_DPAD_BUTTON_2_DOWN 11
#define MES_DPAD_BUTTON_2_UP 12
#define MES_DPAD_BUTTON_3_DOWN 13
#define MES_DPAD_BUTTON_3_UP 14
#define MES_DPAD_BUTTON_4_DOWN 15
#define MES_DPAD_BUTTON_4_UP 16
//
// Events that typically use radio broadcast:
//
#define MES_BROADCAST_GENERAL_ID 2000
#endif

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@ -35,6 +35,7 @@
#include "MicroBitMessageBus.h"
#include "MicroBitBLEManager.h"
#include "MicroBitRadio.h"
// MicroBit::flags values
#define MICROBIT_FLAG_SCHEDULER_RUNNING 0x00000001
@ -108,6 +109,7 @@ class MicroBit
// Bluetooth related member variables.
MicroBitBLEManager bleManager;
MicroBitRadio radio;
BLEDevice *ble;
/**

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@ -39,6 +39,11 @@
#define MICROBIT_BLE_PAIR_SUCCESSFUL 0x08
#define MICROBIT_BLE_PAIRING_TIMEOUT 90
#define MICROBIT_BLE_POWER_LEVELS 8
#define MICROBIT_BLE_MAXIMUM_BONDS 4
#define MICROBIT_BLE_ENABLE_BONDING true
#define MICROBIT_BLE_REQUIRE_MITM true
extern const int8_t MICROBIT_BLE_POWER_LEVEL[];
/**
* Class definition for the MicroBitBLEManager.

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@ -44,6 +44,8 @@
#define MICROBIT_ID_GESTURE 27 // Gesture events
#define MICROBIT_ID_THERMOMETER 28
#define MICROBIT_ID_RADIO 29
#define MICROBIT_ID_RADIO_DATA_READY 30
#define MICROBIT_ID_NOTIFY 1023 // Notfication channel, for general purpose synchronisation
#define MICROBIT_ID_NOTIFY_ONE 1022 // Notfication channel, for general purpose synchronisation

174
inc/MicroBitRadio.h Normal file
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@ -0,0 +1,174 @@
#ifndef MICROBIT_RADIO_H
#define MICROBIT_RADIO_H
#include "mbed.h"
/**
* Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
*
* The nrf51822 RADIO module supports a number of proprietary modes of operation in addition to the typical BLE usage.
* This class uses one of these modes to enable simple, point to multipoint communication directly between micro:bits.
*
* TODO: The protocols implemented here do not currently perform any significant form of energy management,
* which means that they will consume far more energy than their BLE equivalent. Later versions of the protocol
* should look to address this through energy efficient broadcast techniques / sleep scheduling. In particular, the GLOSSY
* approach to efficienct rebroadcast and network synchronisation would likely provide an effective future step.
*
* TODO: Meshing should also be considered - again a GLOSSY approach may be effective here, and highly complementary to
* the master/slave arachitecture of BLE.
*
* TODO: This implementation only operates whilst the BLE stack is disabled. The nrf51822 provides a timeslot API to allow
* BLE to cohabit with other protocols. Future work to allow this colocation would be benefical, and would also allow for the
* creation of wireless BLE bridges.
*
* NOTE: This API does not contain any form of encryption, authentication or authorization. It's purpose is solely for use as a
* teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
* For serious applications, BLE should be considered a substantially more secure alternative.
*/
// Status Flags
#define MICROBIT_RADIO_STATUS_INITIALISED 0x0001
// Default configuration values
#define MICROBIT_RADIO_BASE_ADDRESS 0x75626974
#define MICROBIT_RADIO_DEFAULT_GROUP 0
#define MICROBIT_RADIO_DEFAULT_TX_POWER 6
#define MICROBIT_RADIO_DEFAULT_FREQUENCY 7
#define MICROBIT_RADIO_MAX_PACKET_SIZE 32
#define MICROBIT_RADIO_HEADER_SIZE 4
#define MICROBIT_RADIO_MAXIMUM_RX_BUFFERS 4
// Known Protocol Numbers
#define MICROBIT_RADIO_PROTOCOL_DATAGRAM 1 // A simple, single frame datagram. a little like UDP but with smaller packets. :-)
#define MICROBIT_RADIO_PROTOCOL_EVENTBUS 2 // Transparent propogation of events from one micro:bit to another.
// Events
#define MICROBIT_RADIO_EVT_DATAGRAM 1 // Event to signal that a new datagram has been received.
struct PacketBuffer
{
uint8_t length; // The length of the remaining bytes in the packet. includes protocol/version/group fields, excluding the length field itself.
uint8_t version; // Protocol version code.
uint8_t group; // ID of the group to which this packet belongs.
uint8_t protocol; // Inner protocol number c.f. those issued by IANA for IP protocols
uint8_t payload[MICROBIT_RADIO_MAX_PACKET_SIZE]; // User / higher layer protocol data
PacketBuffer *next; // Linkage, to allow this and other protocols to queue packets pending processing.
};
#include "MicroBitRadioDatagram.h"
#include "MicroBitRadioEvent.h"
class MicroBitRadio : MicroBitComponent
{
uint8_t group; // The radio group to which this micro:bit belongs.
uint8_t queueDepth; // The number of packets in the receiver queue.
PacketBuffer *rxQueue; // A linear list of incoming packets, queued awaiting processing.
PacketBuffer *rxBuf; // A pointer to the buffer being actively used by the RADIO hardware.
public:
MicroBitRadioDatagram datagram; // A simple datagram service.
MicroBitRadioEvent event; // A simple event handling service.
static MicroBitRadio *instance; // A singleton reference, used purely by the interrupt service routine.
/**
* Constructor.
*
* Initialise the MicroBitRadio. Note that this class is demand activated, so most resources are only
* committed if send/recv or event registrations calls are made.
*/
MicroBitRadio(uint16_t id);
/**
* Change the output power level of the transmitter to the given value.
*
* @param power a value in the range 0..7, where 0 is the lowest power and 7 is the highest.
* @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the value is out of range.
*
*/
int setTransmitPower(int power);
/**
* Change the transmission and reception band of the radio to the given channel
*
* @param band a frequency band in the range 0 - 100. Each step is 1MHz wide, based at 2400MHz.
* @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the value is out of range,
* or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
*
*/
int setFrequencyBand(int band);
/**
* Retrieve a pointer to the currently allocated recieve buffer. This is the area of memory
* actively being used by the radio hardware to store incoming data.
*
* @return a pointer to the current receive buffer
*/
PacketBuffer* getRxBuf();
/**
* Attempt to queue a buffer received by the radio hardware, if sufficient space is available.
*
* @return MICROBIT_OK on success, or MICROBIT_NO_RESOURCES if a replacement receiver buffer
* could not be allocated (either by policy or memory exhaustion).
*/
int queueRxBuf();
/**
* Initialises the radio for use as a multipoint sender/receiver
* @return MICROBIT_OK on success, MICROBIT_NOT_SUPPORTED if SoftDevice is enabled.
*/
int enable();
/**
* Disables the radio for use as a multipoint sender/receiver.
* @return MICROBIT_OK on success, MICROBIT_NOT_SUPPORTED if SoftDevice is enabled.
*/
int disable();
/**
* Sets the radio to listen to packets sent with the given group id.
*
* @param group The group to join. A micro:bit can only listen to one group ID at any time.
* @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
*/
int setGroup(uint8_t group);
/**
* A background, low priority callback that is triggered whenever the processor is idle.
* Here, we empty our queue of received packets, and pass them onto higher level protocol handlers.
*
* We provide optimised handling of well known, simple protocols and events on the MicroBitMessageBus
* to provide extensibility to other protocols that may be written in the future.
*/
virtual void idleTick();
/**
* Determines the number of packets ready to be processed.
* @return The number of packets in the receive buffer.
*/
int dataReady();
/**
* Retrieves the next packet from the receive buffer.
* If a data packet is available, then it will be returned immediately to
* the caller. This call will also dequeue the buffer.
*
* NOTE: Once recv() has been called, it is the callers resposibility to
* delete the buffer when appropriate.
*
* @return The buffer containing the the packet. If no data is available, NULL is returned.
*/
PacketBuffer* recv();
/**
* Transmits the given buffer onto the broadcast radio.
* The call will wait until the transmission of the packet has completed before returning.
*
* @param data The packet contents to transmit.
* @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
*/
int send(PacketBuffer *buffer);
};
#endif

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@ -0,0 +1,77 @@
#ifndef MICROBIT_RADIO_DATAGRAM_H
#define MICROBIT_RADIO_DATAGRAM_H
#include "mbed.h"
#include "MicroBitRadio.h"
/**
* Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
*
* This class provides the ability to broadcast simple text or binary messages to other micro:bits in the vicinity
* It is envisaged that this would provide the basis for children to experiment with building their own, simple,
* custom protocols.
*
* NOTE: This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a
* teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
* For serious applications, BLE should be considered a substantially more secure alternative.
*/
class MicroBitRadioDatagram
{
PacketBuffer *rxQueue; // A linear list of incoming packets, queued awaiting processing.
public:
/**
* Constructor.
*/
MicroBitRadioDatagram();
/**
* Retreives packet payload data into the given buffer.
* If a data packet is already available, then it will be returned immediately to the caller.
* If no data is available the EmptyString is returned, then MICROBIT_INVALID_PARAMETER is returned.
*
* @param buf A pointer to a valid memory location where the received data is to be stored.
* @param len The maximum amount of data that can safely be stored in 'buf'
*
* @return The length of the data stored, or MICROBIT_INVALID_PARAMETER if no data is available, or the memory regions provided are invalid.
*/
int recv(uint8_t *buf, int len);
/**
* Retreives packet payload data into the given buffer.
* If a data packet is already available, then it will be returned immediately to the caller,
* in the form of a string. If no data is available the EmptyString is returned.
*
* @return the data received, or the EmptyString if no data is available.
*/
ManagedString recv();
/**
* Transmits the given buffer onto the broadcast radio.
* The call will wait until the transmission of the packet has completed before returning.
*
* @param buffer The packet contents to transmit.
* @param len The number of bytes to transmit.
* @return MICROBIT_OK on success.
*/
int send(uint8_t *buffer, int len);
/**
* Transmits the given string onto the broadcast radio.
* The call will wait until the transmission of the packet has completed before returning.
*
* @param data The packet contents to transmit.
* @return MICROBIT_OK on success.
*/
int send(ManagedString data);
/**
* Protocol handler callback. This is called when the radio receives a packet marked as a datagram.
* This function process this packet, and queues it for user reception.
*/
void packetReceived();
};
#endif

67
inc/MicroBitRadioEvent.h Normal file
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@ -0,0 +1,67 @@
#ifndef MICROBIT_RADIO_EVENT_H
#define MICROBIT_RADIO_EVENT_H
#include "mbed.h"
#include "MicroBitRadio.h"
/**
* Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
*
* This class provides the ability to extend the micro:bit's MessageBus to other micro:bits in the vicinity,
* in a very similar way to the MicroBitEventService for BLE interfaces.
* It is envisaged that this would provide the basis for children to experiment with building their own, simple,
* custom asynchronous events and actions.
*
* NOTE: This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a
* teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
* For serious applications, BLE should be considered a substantially more secure alternative.
*/
class MicroBitRadioEvent
{
bool suppressForwarding; // A private flag used to prevent event forwarding loops.
public:
/**
* Constructor.
*/
MicroBitRadioEvent();
/**
* Associates the given MessageBus events with the radio channel.
* Once registered, all events matching the given registration sent to this micro:bit's
* MessageBus will be automatically retrasmitted on the radio.
*
* @param id The ID of the events to register.
* @param value the VALUE of the event to register. use MICROBIT_EVT_ANY for all event values matching the given ID.
*
* @return MICROBIT_OK on success.
*/
int listen(uint16_t id, uint16_t value);
/**
* Disassociates the given MessageBus events with the radio channel.
*
* @param id The ID of the events to deregister.
* @param value the VALUE of the event to deregister. use MICROBIT_EVT_ANY for all event values matching the given ID.
*
* @return MICROBIT_OK on success.
*/
int ignore(uint16_t id, uint16_t value);
/**
* Protocol handler callback. This is called when the radio receives a packet marked as using the event protocol.
* This function process this packet, and fires the event contained inside onto the local MessageBus.
*/
void packetReceived();
/**
* Event handler callback. This is called whenever an event is received matching one of those registered through
* the registerEvent() method described above. Upon receiving such an event, it is wrapped into
* a radio packet and transmitted to any othe rmicro:bits in the same group.
*/
void eventReceived(MicroBitEvent e);
};
#endif

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@ -41,6 +41,9 @@ set(YOTTA_AUTO_MICROBIT-DAL_CPP_FILES
"ble-services/MicroBitButtonService.cpp"
"ble-services/MicroBitIOPinService.cpp"
"ble-services/MicroBitTemperatureService.cpp"
"ble-services/MicroBitRadio.cpp"
"ble-services/MicroBitRadioDatagram.cpp"
"ble-services/MicroBitRadioEvent.cpp"
)
execute_process(WORKING_DIRECTORY "../../yotta_modules/${PROJECT_NAME}" COMMAND "git" "log" "--pretty=format:%h" "-n" "1" OUTPUT_VARIABLE git_hash)

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@ -105,6 +105,7 @@ MicroBit::MicroBit() :
MICROBIT_ID_IO_P15,MICROBIT_ID_IO_P16,MICROBIT_ID_IO_P19,
MICROBIT_ID_IO_P20),
bleManager(),
radio(MICROBIT_ID_RADIO),
ble(NULL)
{
}

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@ -21,13 +21,7 @@
#pragma GCC diagnostic pop
#endif
#define MICROBIT_BLE_ENABLE_BONDING true
#define MICROBIT_BLE_REQUIRE_MITM true
#define MICROBIT_PAIRING_FADE_SPEED 4
#define MICROBIT_BLE_POWER_LEVELS 8
#define MICROBIT_BLE_MAXIMUM_BONDS 4
const char* MICROBIT_BLE_MANUFACTURER = NULL;
const char* MICROBIT_BLE_MODEL = "BBC micro:bit";

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@ -0,0 +1,424 @@
#include "MicroBit.h"
/**
* Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
*
* The nrf51822 RADIO module supports a number of proprietary modes of operation oher than the typical BLE usage.
* This class uses one of these modes to enable simple, point to multipoint communication directly between micro:bits.
*
* TODO: The protocols implemented here do not currently perform any significant form of energy management,
* which means that they will consume far more energy than their BLE equivalent. Later versions of the protocol
* should look to address this through energy efficient broadcast techbiques / sleep scheduling. In particular, the GLOSSY
* approach to efficient rebroadcast and network synchronisation would likely provide an effective future step.
*
* TODO: Meshing should also be considered - again a GLOSSY approach may be effective here, and highly complementary to
* the master/slave arachitecture of BLE.
*
* TODO: This implementation may only operated whilst the BLE stack is disabled. The nrf51822 provides a timeslot API to allow
* BLE to cohabit with other protocols. Future work to allow this colocation would be benefical, and would also allow for the
* creation of wireless BLE bridges.
*
* NOTE: This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a
* teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
* For serious applications, BLE should be considered a substantially more secure alternative.
*/
MicroBitRadio* MicroBitRadio::instance = NULL;
extern "C" void RADIO_IRQHandler(void)
{
// Move on to the next buffer, if possible.
MicroBitRadio::instance->queueRxBuf();
NRF_RADIO->PACKETPTR = (uint32_t) MicroBitRadio::instance->getRxBuf();
// Start listening for the next packet.
NRF_RADIO->EVENTS_END = 0;
NRF_RADIO->TASKS_START = 1;
}
/**
* Constructor.
*
* Initialise the MicroBitRadio. Note that this class is demand activated, so most resources are only committed
* if send/recv or event registrations calls are made.
*/
MicroBitRadio::MicroBitRadio(uint16_t id) : datagram()
{
this->id = id;
this->status = 0;
this->group = 0;
this->queueDepth = 0;
this->rxQueue = NULL;
this->rxBuf = NULL;
instance = this;
}
/**
* Change the output power level of the transmitter to the given value.
*
* @param power a value in the range 0..7, where 0 is the lowest power and 7 is the highest.
* @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the value is out of range.
*
*/
int MicroBitRadio::setTransmitPower(int power)
{
if (power < 0 || power >= MICROBIT_BLE_POWER_LEVELS)
return MICROBIT_INVALID_PARAMETER;
NRF_RADIO->TXPOWER = (uint32_t)MICROBIT_BLE_POWER_LEVEL[power];
return MICROBIT_OK;
}
/**
* Change the transmission and reception band of the radio to the given channel
*
* @param band a frequency band in the range 0 - 100. Each step is 1MHz wide, based at 2400MHz.
* @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the value is out of range,
* or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
*
*/
int MicroBitRadio::setFrequencyBand(int band)
{
if (uBit.ble)
return MICROBIT_NOT_SUPPORTED;
if (band < 0 || band > 100)
return MICROBIT_INVALID_PARAMETER;
NRF_RADIO->FREQUENCY = (uint32_t)band;
return MICROBIT_OK;
}
/**
* Retrieve a pointer to the currently allocated receive buffer. This is the area of memory
* actively being used by the radio hardware to store incoming data.
*
* @return a pointer to the current receive buffer
*/
PacketBuffer* MicroBitRadio::getRxBuf()
{
return rxBuf;
}
/**
* Attempt to queue a buffer received by the radio hardware, if sufficient space is available.
*
* @return MICROBIT_OK on success, or MICROBIT_NO_RESOURCES if a replacement receiver buffer
* could not be allocated (either by policy or memory exhaustion).
*/
int MicroBitRadio::queueRxBuf()
{
if (rxBuf == NULL)
return MICROBIT_INVALID_PARAMETER;
if (queueDepth >= MICROBIT_RADIO_MAXIMUM_RX_BUFFERS)
return MICROBIT_NO_RESOURCES;
// Ensure that a replacement buffer is available before queuing.
PacketBuffer *newRxBuf = new PacketBuffer();
if (newRxBuf == NULL)
return MICROBIT_NO_RESOURCES;
// We add to the tail of the queue to preserve causal ordering.
rxBuf->next = NULL;
if (rxQueue == NULL)
{
rxQueue = rxBuf;
}
else
{
PacketBuffer *p = rxQueue;
while (p->next != NULL)
p = p->next;
p->next = rxBuf;
}
// Increase our received packet count
queueDepth++;
// Allocate a new buffer for the receiver hardware to use. the old on will be passed on to higher layer protocols/apps.
rxBuf = newRxBuf;
return MICROBIT_OK;
}
/**
* Initialises the radio for use as a multipoint sender/receiver.
* This is currently only possible if the BLE stack (Soft Device) is disabled.
*
* @return MICROBIT_OK on success, MICROBIT_NOT_SUPPORTED if SoftDevice is enabled.
*/
int MicroBitRadio::enable()
{
// If the device is already initialised, then there's nothing to do.
if (status & MICROBIT_RADIO_STATUS_INITIALISED)
return MICROBIT_OK;
// Only attempt to enable this radio mode if BLE is disabled.
if (uBit.ble)
return MICROBIT_NOT_SUPPORTED;
// If this is the first time we've been enable, allocate out receive buffers.
if (rxBuf == NULL)
rxBuf = new PacketBuffer();
if (rxBuf == NULL)
return MICROBIT_NO_RESOURCES;
// Enable the High Frequency clock on the processor. This is a pre-requisite for
// the RADIO module. Without this clock, no communication is possible.
NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
NRF_CLOCK->TASKS_HFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
// Bring up the nrf51822 RADIO module in Nordic's proprietary 1MBps packet radio mode.
setTransmitPower(MICROBIT_RADIO_DEFAULT_TX_POWER);
setFrequencyBand(MICROBIT_RADIO_DEFAULT_FREQUENCY);
// Configure for 1Mbps throughput.
// This may sound excessive, but running a high data rates reduces the chances of collisions...
NRF_RADIO->MODE = RADIO_MODE_MODE_Nrf_1Mbit;
// Configure the addresses we use for this protocol. We run ANONYMOUSLY at the core.
// A 40 bit addresses is used. The first 32 bits match the ASCII character code for "uBit".
// Statistically, this provides assurance to avoid other similar 2.4GHz protocols that may be in the vicinity.
// We also map the assigned 8-bit GROUP id into the PREFIX field. This allows the RADIO hardware to perform
// address matching for us, and only generate an interrupt when a packet matching our group is received.
NRF_RADIO->BASE0 = MICROBIT_RADIO_BASE_ADDRESS;
// Join the default group. This will configure the remaining byte in the RADIO hardware module.
setGroup(MICROBIT_RADIO_DEFAULT_GROUP);
// The RADIO hardware module supports the use of multiple addresses, but as we're running anonymously, we only need one.
// Configure the RADIO module to use the default address (address 0) for both send and receive operations.
NRF_RADIO->TXADDRESS = 0;
NRF_RADIO->RXADDRESSES = 1;
// Packet layout configuration. The nrf51822 has a highly capable and flexible RADIO module that, in addition to transmission
// and reception of data, also contains a LENGTH field, two optional additional 1 byte fields (S0 and S1) and a CRC calculation.
// Configure the packet format for a simple 8 bit length field and no additional fields.
NRF_RADIO->PCNF0 = 0x00000008;
NRF_RADIO->PCNF1 = 0x02040000 | MICROBIT_RADIO_MAX_PACKET_SIZE;
// Most communication channels contain some form of checksum - a mathematical calculation taken based on all the data
// in a packet, that is also sent as part of the packet. When received, this calculation can be repeated, and the results
// from the sender and receiver compared. If they are different, then some corruption of the data ahas happened in transit,
// and we know we can't trust it. The nrf51822 RADIO uses a CRC for this - a very effective checksum calculation.
//
// Enable automatic 16bit CRC generation and checking, and configure how the CRC is calculated.
NRF_RADIO->CRCCNF = RADIO_CRCCNF_LEN_Two;
NRF_RADIO->CRCINIT = 0xFFFF;
NRF_RADIO->CRCPOLY = 0x11021;
// Set the start random value of the data whitening algorithm. This can be any non zero number.
NRF_RADIO->DATAWHITEIV = 0x18;
// Set up the RADIO module to read and write from our internal buffer.
NRF_RADIO->PACKETPTR = (uint32_t)rxBuf;
// Configure the hardware to issue an interrupt whenever a task is complete (e.g. send/receive).
NRF_RADIO->INTENSET = 0x00000008;
NVIC_ClearPendingIRQ(RADIO_IRQn);
NVIC_EnableIRQ(RADIO_IRQn);
// Start listening for the next packet
NRF_RADIO->EVENTS_READY = 0;
NRF_RADIO->TASKS_RXEN = 1;
while(NRF_RADIO->EVENTS_READY == 0);
NRF_RADIO->EVENTS_END = 0;
NRF_RADIO->TASKS_START = 1;
// register ourselves for a callback event, in order to empty the receive queue.
uBit.addIdleComponent(this);
// Done. Record that our RADIO is configured.
status |= MICROBIT_RADIO_STATUS_INITIALISED;
return MICROBIT_OK;
}
/**
* Disables the radio for use as a multipoint sender/receiver.
* @return MICROBIT_OK on success, MICROBIT_NOT_SUPPORTED if SoftDevice is enabled.
*/
int MicroBitRadio::disable()
{
// Only attempt to enable.disable the radio if the protocol is alreayd running.
if (uBit.ble)
return MICROBIT_NOT_SUPPORTED;
if (!(status & MICROBIT_RADIO_STATUS_INITIALISED))
return MICROBIT_OK;
// Disable interrupts and STOP any ongoing packet reception.
NVIC_DisableIRQ(RADIO_IRQn);
NRF_RADIO->EVENTS_DISABLED = 0;
NRF_RADIO->TASKS_DISABLE = 1;
while(NRF_RADIO->EVENTS_DISABLED == 0);
// deregister ourselves from the callback event used to empty the receive queue.
uBit.removeIdleComponent(this);
return MICROBIT_OK;
}
/**
* Sets the radio to listen to packets sent with the given group id.
*
* @param group The group to join. A micro:bit can only listen to one group ID at any time.
* @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
*/
int MicroBitRadio::setGroup(uint8_t group)
{
if (uBit.ble)
return MICROBIT_NOT_SUPPORTED;
// Record our group id locally
this->group = group;
// Also append it to the address of this device, to allow the RADIO module to filter for us.
NRF_RADIO->PREFIX0 = (uint32_t)group;
return MICROBIT_OK;
}
/**
* A background, low priority callback that is triggered whenever the processor is idle.
* Here, we empty our queue of received packets, and pass them onto higher level protocol handlers.
*
* We provide optimised handling of well known, simple protocols and events on the MicroBitMessageBus
* to provide extensibility to other protocols that may be written in the future.
*/
void MicroBitRadio::idleTick()
{
// Walk the list of packets and process each one.
while(rxQueue)
{
PacketBuffer *p = rxQueue;
switch (p->protocol)
{
case MICROBIT_RADIO_PROTOCOL_DATAGRAM:
datagram.packetReceived();
break;
case MICROBIT_RADIO_PROTOCOL_EVENTBUS:
event.packetReceived();
break;
default:
MicroBitEvent(MICROBIT_ID_RADIO_DATA_READY, p->protocol);
}
// If the packet was processed, it will have been recv'd, and taken from the queue.
// If this was a packet for an unknown protocol, it will still be there, so simply free it.
if (p == rxQueue)
{
recv();
delete p;
}
}
}
/**
* Determines the number of packets ready to be processed.
* @return The number of packets in the receive buffer.
*/
int MicroBitRadio::dataReady()
{
return queueDepth;
}
/**
* Retrieves the next packet from the receive buffer.
* If a data packet is available, then it will be returned immediately to
* the caller. This call will also dequeue the buffer.
*
* NOTE: Once recv() has been called, it is the callers resposibility to
* delete the buffer when appropriate.
*
* @return The buffer containing the the packet. If no data is available, NULL is returned.
*/
PacketBuffer* MicroBitRadio::recv()
{
PacketBuffer *p = rxQueue;
if (p)
{
rxQueue = rxQueue->next;
queueDepth--;
}
return p;
}
/**
* Transmits the given buffer onto the broadcast radio.
* The call will wait until the transmission of the packet has completed before returning.
*
* @param data The packet contents to transmit.
* @return MICROBIT_OK on success, or MICROBIT_NOT_SUPPORTED if the BLE stack is running.
*/
int MicroBitRadio::send(PacketBuffer *buffer)
{
if (uBit.ble)
return MICROBIT_NOT_SUPPORTED;
if (buffer == NULL)
return MICROBIT_INVALID_PARAMETER;
if (buffer->length > MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE - 1)
return MICROBIT_INVALID_PARAMETER;
// Firstly, disable the Radio interrupt. We want to wait until the trasmission completes.
NVIC_DisableIRQ(RADIO_IRQn);
// Turn off the transceiver.
NRF_RADIO->EVENTS_DISABLED = 0;
NRF_RADIO->TASKS_DISABLE = 1;
while(NRF_RADIO->EVENTS_DISABLED == 0);
// Configure the radio to send the buffer provided.
NRF_RADIO->PACKETPTR = (uint32_t) buffer;
// Turn on the transmitter, and wait for it to signal that it's ready to use.
NRF_RADIO->EVENTS_READY = 0;
NRF_RADIO->TASKS_TXEN = 1;
while (NRF_RADIO->EVENTS_READY == 0);
// Start transmission and wait for end of packet.
NRF_RADIO->TASKS_START = 1;
NRF_RADIO->EVENTS_END = 0;
while(NRF_RADIO->EVENTS_END == 0);
// Return the radio to using the default receive buffer
NRF_RADIO->PACKETPTR = (uint32_t) rxBuf;
// Turn off the transmitter.
NRF_RADIO->EVENTS_DISABLED = 0;
NRF_RADIO->TASKS_DISABLE = 1;
while(NRF_RADIO->EVENTS_DISABLED == 0);
// Start listening for the next packet
NRF_RADIO->EVENTS_READY = 0;
NRF_RADIO->TASKS_RXEN = 1;
while(NRF_RADIO->EVENTS_READY == 0);
NRF_RADIO->EVENTS_END = 0;
NRF_RADIO->TASKS_START = 1;
// Re-enable the Radio interrupt.
NVIC_ClearPendingIRQ(RADIO_IRQn);
NVIC_EnableIRQ(RADIO_IRQn);
return MICROBIT_OK;
}

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#include "MicroBit.h"
/**
* Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
*
* This class provides the ability to broadcast simple text or binary messages to other micro:bits in the vicinity
* It is envisaged that this would provide the basis for children to experiment with building their own, simple,
* custom protocols.
*
* NOTE: This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a
* teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
* For serious applications, BLE should be considered a substantially more secure alternative.
*/
/**
* Constructor.
*/
MicroBitRadioDatagram::MicroBitRadioDatagram()
{
rxQueue = NULL;
}
/**
* Retreives packet payload data into the given buffer.
* If a data packet is already available, then it will be returned immediately to the caller.
* If no data is available the EmptyString is returned, then MICROBIT_INVALID_PARAMETER is returned.
*
* @param buf A pointer to a valid memory location where the received data is to be stored.
* @param len The maximum amount of data that can safely be stored in 'buf'
*
* @return The length of the data stored, or MICROBIT_INVALID_PARAMETER if no data is available, or the memory regions provided are invalid.
*/
int MicroBitRadioDatagram::recv(uint8_t *buf, int len)
{
if (buf == NULL || rxQueue == NULL || len < 0)
return MICROBIT_INVALID_PARAMETER;
// Take the first buffer from the queue.
PacketBuffer *p = rxQueue;
rxQueue = rxQueue->next;
int l = min(len, p->length - MICROBIT_RADIO_HEADER_SIZE - 1);
// Fill in the buffer provided, if possible.
memcpy(buf, p->payload, l);
delete p;
return l;
}
/**
* Retreives packet payload data into the given buffer.
* If a data packet is already available, then it will be returned immediately to the caller,
* in the form of a string. If no data is available the EmptyString is returned.
*
* @return the data received, or the EmptyString if no data is available.
*/
ManagedString MicroBitRadioDatagram::recv()
{
PacketBuffer *p = rxQueue;
rxQueue = rxQueue->next;
ManagedString s((const char *)p->payload, p->length - MICROBIT_RADIO_HEADER_SIZE - 1);
delete p;
return s;
}
/**
* Transmits the given buffer onto the broadcast radio.
* The call will wait until the transmission of the packet has completed before returning.
*
* @param buffer The packet contents to transmit.
* @param len The number of bytes to transmit.
* @return MICROBIT_OK on success.
*/
int MicroBitRadioDatagram::send(uint8_t *buffer, int len)
{
if (buffer == NULL || len < 0 || len > MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE - 1)
return MICROBIT_INVALID_PARAMETER;
PacketBuffer buf;
buf.length = len + MICROBIT_RADIO_HEADER_SIZE - 1;
buf.version = 1;
buf.group = 0;
buf.protocol = MICROBIT_RADIO_PROTOCOL_DATAGRAM;
memcpy(buf.payload, buffer, len);
return uBit.radio.send(&buf);
}
/**
* Transmits the given string onto the broadcast radio.
* The call will wait until the transmission of the packet has completed before returning.
*
* @param data The packet contents to transmit.
* @return MICROBIT_OK on success.
*/
int MicroBitRadioDatagram::send(ManagedString data)
{
return send((uint8_t *)data.toCharArray(), data.length());
}
/**
* Protocol handler callback. This is called when the radio receives a packet marked as a datagram.
* This function process this packet, and queues it for user reception.
*/
void MicroBitRadioDatagram::packetReceived()
{
PacketBuffer *packet = uBit.radio.recv();
int queueDepth = 0;
// We add to the tail of the queue to preserve causal ordering.
packet->next = NULL;
if (rxQueue == NULL)
{
rxQueue = packet;
}
else
{
PacketBuffer *p = rxQueue;
while (p->next != NULL)
{
p = p->next;
queueDepth++;
}
if (queueDepth >= MICROBIT_RADIO_MAXIMUM_RX_BUFFERS)
{
delete packet;
return;
}
p->next = packet;
}
MicroBitEvent(MICROBIT_ID_RADIO, MICROBIT_RADIO_EVT_DATAGRAM);
}

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#include "MicroBit.h"
/**
* Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
*
* This class provides the ability to extend the micro:bit's MessageBus to other micro:bits in the vicinity,
* in a very similar way to the MicroBitEventService for BLE interfaces.
* It is envisaged that this would provide the basis for children to experiment with building their own, simple,
* custom asynchronous events.
*
* NOTE: This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a
* teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
* For serious applications, BLE should be considered a substantially more secure alternative.
*/
/**
* Constructor.
*/
MicroBitRadioEvent::MicroBitRadioEvent()
{
suppressForwarding = false;
}
/**
* Associates the given MessageBus events with the radio channel.
* Once registered, all events matching the given registration sent to this micro:bit's
* MessageBus will be automaticlaly retrasmitted on the radio.
*
* @param id The ID of the events to register.
* @param value the VALUE of the event to register. use MICROBIT_EVT_ANY for all event values matching the given id.
*
* @return MICROBIT_OK on success.
*/
int MicroBitRadioEvent::listen(uint16_t id, uint16_t value)
{
return uBit.MessageBus.listen(id, value, this, &MicroBitRadioEvent::eventReceived, MESSAGE_BUS_LISTENER_IMMEDIATE);
}
/**
* Disassociates the given MessageBus events with the radio channel.
*
* @param id The ID of the events to deregister.
* @param value the VALUE of the event to deregister. use MICROBIT_EVT_ANY for all event values matching the given id.
*
* @return MICROBIT_OK on success.
*/
int MicroBitRadioEvent::ignore(uint16_t id, uint16_t value)
{
return uBit.MessageBus.ignore(id, value, this, &MicroBitRadioEvent::eventReceived);
}
/**
* Protocol handler callback. This is called when the radio receives a packet marked as an event
* This function process this packet, and fires the event contained inside onto the local MessageBus.
*/
void MicroBitRadioEvent::packetReceived()
{
PacketBuffer *p = uBit.radio.recv();
MicroBitEvent *e = (MicroBitEvent *) p->payload;
suppressForwarding = true;
e->fire();
suppressForwarding = false;
delete p;
}
/**
* Event handler callback. This is called whenever an event is received matching one of those registered through
* the registerEvent() method described above. Upon receiving such an event, it is wrapped into
* a radio packet and transmitted to any othe rmicro:bits in the same group.
*/
void MicroBitRadioEvent::eventReceived(MicroBitEvent e)
{
if(suppressForwarding)
return;
PacketBuffer buf;
buf.length = sizeof(MicroBitEvent) + MICROBIT_RADIO_HEADER_SIZE - 1;
buf.version = 1;
buf.group = 0;
buf.protocol = MICROBIT_RADIO_PROTOCOL_EVENTBUS;
memcpy(buf.payload, (const uint8_t *)&e, sizeof(MicroBitEvent));
uBit.radio.send(&buf);
}