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https://github.com/betaflight/betaflight.git
synced 2025-07-23 00:05:33 +03:00
Add support for 2 softserial ports on PWM4+5/TIM3_CH1+2/PA6+PA7 and
PWM6+7/TIM3_CH3+4/PB0+PB1 Update software serial to monitor serial pins for signal changes instead of periodically sampling pin signals. When reading the data the timer used is syncronized to the falling edge of the start bit which allows for better syncronisation at higher speeds. The code has been tested OK from 1200 baud to 19200. 38400 baud was tested and partially usable but has been disabled because there are too many transmit and receive errors, especially when transmitting and receiving at the same time. Due to the way a single timer is used for transmitting and receiving, if data comes in while transmitting the system may incorrectly transmit a short or long bit. However at 19200 and below this didn't cause a problem in the limited testing I performed.
This commit is contained in:
Dominic Clifton
parent
bd809bca1b
commit
c7de7d2ebc
9 changed files with 212 additions and 138 deletions
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@ -3,14 +3,18 @@
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#define SOFT_SERIAL_TIMER_MHZ 3
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#define SOFT_SERIAL_1_TIMER_RX_HARDWARE 4
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#define SOFT_SERIAL_1_TIMER_TX_HARDWARE 5
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#define SOFT_SERIAL_2_TIMER_RX_HARDWARE 6
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#define SOFT_SERIAL_2_TIMER_TX_HARDWARE 7
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#define RX_TOTAL_BITS 8
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#define RX_TOTAL_BITS 10
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#define TX_TOTAL_BITS 10
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#define MAX_SOFTSERIAL_PORTS 2
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softSerial_t softSerialPorts[MAX_SOFTSERIAL_PORTS];
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void onSerialTimer(uint8_t portIndex, uint16_t capture);
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void onSerialRxPinChange(uint8_t portIndex, uint16_t capture);
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uint8_t readRxSignal(softSerial_t *softSerial)
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{
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@ -69,19 +73,17 @@ void serialInputPortConfig(const timerHardware_t *timerHardwarePtr)
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softSerialGPIOConfig(timerHardwarePtr->gpio, timerHardwarePtr->pin, Mode_IPU);
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}
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#define TICKS_PER_BIT 3
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bool isTimerPeriodTooLarge(uint32_t timerPeriod)
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{
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return timerPeriod > 0xFFFF;
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}
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void serialTimerConfig(const timerHardware_t *timerHardwarePtr, uint32_t baud, uint8_t reference, timerCCCallbackPtr callback)
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void serialTimerTxConfig(const timerHardware_t *timerHardwarePtr, uint8_t reference, uint32_t baud)
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{
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uint32_t clock = SystemCoreClock;
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uint32_t timerPeriod;
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do {
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timerPeriod = clock / (baud * TICKS_PER_BIT);
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timerPeriod = clock / baud;
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if (isTimerPeriodTooLarge(timerPeriod)) {
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if (clock > 1) {
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clock = clock / 2;
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@ -93,8 +95,29 @@ void serialTimerConfig(const timerHardware_t *timerHardwarePtr, uint32_t baud, u
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} while (isTimerPeriodTooLarge(timerPeriod));
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uint8_t mhz = SystemCoreClock / 1000000;
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timerInConfig(timerHardwarePtr, timerPeriod, mhz);
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configureTimerCaptureCompareInterrupt(timerHardwarePtr, reference, callback);
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timerConfigure(timerHardwarePtr, timerPeriod, mhz);
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configureTimerCaptureCompareInterrupt(timerHardwarePtr, reference, onSerialTimer);
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}
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void serialICConfig(TIM_TypeDef *tim, uint8_t channel, uint16_t polarity)
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{
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TIM_ICInitTypeDef TIM_ICInitStructure;
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TIM_ICStructInit(&TIM_ICInitStructure);
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TIM_ICInitStructure.TIM_Channel = channel;
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TIM_ICInitStructure.TIM_ICPolarity = polarity;
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TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
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TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
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TIM_ICInitStructure.TIM_ICFilter = 0x0;
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TIM_ICInit(tim, &TIM_ICInitStructure);
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}
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void serialTimerRxConfig(const timerHardware_t *timerHardwarePtr, uint8_t reference)
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{
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// start bit is a FALLING signal
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serialICConfig(timerHardwarePtr->tim, timerHardwarePtr->channel, TIM_ICPolarity_Falling);
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configureTimerCaptureCompareInterrupt(timerHardwarePtr, reference, onSerialRxPinChange);
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}
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void serialOutputPortConfig(const timerHardware_t *timerHardwarePtr)
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@ -102,18 +125,10 @@ void serialOutputPortConfig(const timerHardware_t *timerHardwarePtr)
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softSerialGPIOConfig(timerHardwarePtr->gpio, timerHardwarePtr->pin, Mode_Out_PP);
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}
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void setupSoftSerial1(uint32_t baud, uint8_t inverted)
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void initialiseSoftSerial(softSerial_t *softSerial, uint8_t portIndex, uint32_t baud, uint8_t inverted)
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{
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int portIndex = 0;
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softSerial_t *softSerial = &(softSerialPorts[portIndex]);
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softSerial->port.vTable = softSerialVTable;
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softSerial->port.mode = MODE_RXTX;
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softSerial->port.baudRate = baud;
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softSerial->isInverted = inverted;
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softSerial->rxTimerHardware = &(timerHardware[SOFT_SERIAL_1_TIMER_RX_HARDWARE]);
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softSerial->txTimerHardware = &(timerHardware[SOFT_SERIAL_1_TIMER_TX_HARDWARE]);
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softSerial->port.rxBufferSize = SOFT_SERIAL_BUFFER_SIZE;
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softSerial->port.rxBuffer = softSerial->rxBuffer;
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@ -126,20 +141,56 @@ void setupSoftSerial1(uint32_t baud, uint8_t inverted)
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softSerial->port.txBufferHead = 0;
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softSerial->isTransmittingData = false;
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softSerial->isSearchingForStartBit = true;
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softSerial->isSearchingForStopBit = false;
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softSerial->rxBitIndex = 0;
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softSerial->timerRxCounter = 1;
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serialInputPortConfig(softSerial->rxTimerHardware);
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serialOutputPortConfig(softSerial->txTimerHardware);
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serialInputPortConfig(softSerial->rxTimerHardware);
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setTxSignal(softSerial, 1);
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setTxSignal(softSerial, ENABLE);
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delay(50);
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serialTimerConfig(softSerial->rxTimerHardware, baud, portIndex, onSerialTimer);
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serialTimerTxConfig(softSerial->txTimerHardware, portIndex, baud);
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serialTimerRxConfig(softSerial->rxTimerHardware, portIndex);
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}
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typedef struct softSerialConfiguration_s {
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uint32_t sharedBaudRate;
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bool primaryPortInitialised;
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} softSerialConfiguration_t;
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softSerialConfiguration_t softSerialConfiguration = {
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0,
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false
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};
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void setupSoftSerialPrimary(uint32_t baud, uint8_t inverted)
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{
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uint8_t portIndex = 0;
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softSerial_t *softSerial = &(softSerialPorts[portIndex]);
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softSerial->rxTimerHardware = &(timerHardware[SOFT_SERIAL_1_TIMER_RX_HARDWARE]);
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softSerial->txTimerHardware = &(timerHardware[SOFT_SERIAL_1_TIMER_TX_HARDWARE]);
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initialiseSoftSerial(softSerial, portIndex, baud, inverted);
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softSerialConfiguration.sharedBaudRate = baud;
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softSerialConfiguration.primaryPortInitialised = true;
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}
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void setupSoftSerialSecondary(uint8_t inverted)
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{
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int portIndex = 1;
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softSerial_t *softSerial = &(softSerialPorts[portIndex]);
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softSerial->rxTimerHardware = &(timerHardware[SOFT_SERIAL_2_TIMER_RX_HARDWARE]);
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softSerial->txTimerHardware = &(timerHardware[SOFT_SERIAL_2_TIMER_TX_HARDWARE]);
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initialiseSoftSerial(softSerial, portIndex, softSerialConfiguration.sharedBaudRate, inverted);
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}
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void updateBufferIndex(softSerial_t *softSerial)
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{
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if (softSerial->port.rxBufferTail >= softSerial->port.rxBufferSize - 1) {
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@ -151,81 +202,6 @@ void updateBufferIndex(softSerial_t *softSerial)
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/*********************************************/
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void searchForStartBit(softSerial_t *softSerial)
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{
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char rxSignal = readRxSignal(softSerial);
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if (rxSignal == 1) {
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// start bit not found
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softSerial->timerRxCounter = 1; // process on next timer event
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return;
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}
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// timer is aligned to falling signal of start bit.
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// three ticks per bit.
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softSerial->isSearchingForStartBit = false;
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softSerial->internalRxBuffer = 0;
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softSerial->timerRxCounter = TICKS_PER_BIT + 1; // align to middle of next bit
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softSerial->bitsLeftToReceive = RX_TOTAL_BITS;
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softSerial->rxBitSelectionMask = 1;
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}
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void searchForStopBit(softSerial_t *softSerial)
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{
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char rxSignal;
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softSerial->timerRxCounter = 1;
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rxSignal = readRxSignal(softSerial);
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if (rxSignal != 1) {
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// not found
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return;
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}
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softSerial->isSearchingForStopBit = false;
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softSerial->isSearchingForStartBit = true;
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softSerial->internalRxBuffer &= 0xFF;
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softSerial->port.rxBuffer[softSerial->port.rxBufferTail] = softSerial->internalRxBuffer;
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updateBufferIndex(softSerial);
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}
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void readDataBit(softSerial_t *softSerial)
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{
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softSerial->timerRxCounter = TICKS_PER_BIT; // keep aligned to middle of bit
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char rxSignal = readRxSignal(softSerial);
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if (rxSignal) {
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softSerial->internalRxBuffer |= softSerial->rxBitSelectionMask;
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}
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softSerial->rxBitSelectionMask <<= 1;
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if (--softSerial->bitsLeftToReceive <= 0) {
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softSerial->isSearchingForStopBit = true;
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softSerial->timerRxCounter = 2;
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}
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}
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void processRxState(softSerial_t *softSerial)
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{
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//digitalToggle(softSerial->txTimerHardware->gpio, softSerial->txTimerHardware->pin);
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if (--softSerial->timerRxCounter > 0) {
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return;
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}
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if (softSerial->isSearchingForStartBit) {
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searchForStartBit(softSerial);
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return;
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}
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if (softSerial->isSearchingForStopBit) {
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searchForStopBit(softSerial);
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return;
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}
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readDataBit(softSerial);
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}
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void processTxState(softSerial_t *softSerial)
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{
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char mask;
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@ -245,26 +221,72 @@ void processTxState(softSerial_t *softSerial)
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// build internal buffer, start bit(1) + data bits + stop bit(0)
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softSerial->internalTxBuffer = (1 << (TX_TOTAL_BITS - 1)) | (byteToSend << 1);
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softSerial->bitsLeftToTransmit = TX_TOTAL_BITS;
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// start immediately
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softSerial->timerTxCounter = 1;
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softSerial->isTransmittingData = true;
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return;
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}
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if (--softSerial->timerTxCounter <= 0) {
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mask = softSerial->internalTxBuffer & 1;
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softSerial->internalTxBuffer >>= 1;
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mask = softSerial->internalTxBuffer & 1;
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softSerial->internalTxBuffer >>= 1;
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setTxSignal(softSerial, mask);
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setTxSignal(softSerial, mask);
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softSerial->timerTxCounter = TICKS_PER_BIT;
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if (--softSerial->bitsLeftToTransmit <= 0) {
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softSerial->isTransmittingData = false;
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if (--softSerial->bitsLeftToTransmit <= 0) {
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softSerial->isTransmittingData = false;
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}
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}
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enum {
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FALLING,
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RISING
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};
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void applyChangedBits(softSerial_t *softSerial)
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{
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if (softSerial->rxPinMode == FALLING) {
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uint8_t bitToSet;
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for (bitToSet = softSerial->rxLastRiseAtBitIndex; bitToSet < softSerial->rxBitIndex ; bitToSet++) {
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softSerial->internalRxBuffer |= 1 << bitToSet;
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}
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}
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}
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void prepareForNextRxByte(softSerial_t *softSerial)
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{
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// prepare for next byte
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softSerial->rxBitIndex = 0;
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softSerial->isSearchingForStartBit = true;
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if (softSerial->rxPinMode == RISING) {
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softSerial->rxPinMode = FALLING;
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serialICConfig(softSerial->rxTimerHardware->tim, softSerial->rxTimerHardware->channel, TIM_ICPolarity_Falling);
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}
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}
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void extractAndStoreRxByte(softSerial_t *softSerial)
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{
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uint8_t rxByte = (softSerial->internalRxBuffer >> 1) & 0xFF;
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softSerial->port.rxBuffer[softSerial->port.rxBufferTail] = rxByte;
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updateBufferIndex(softSerial);
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}
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void processRxState(softSerial_t *softSerial)
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{
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if (softSerial->isSearchingForStartBit) {
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return;
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}
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softSerial->rxBitIndex++;
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if (softSerial->rxBitIndex == RX_TOTAL_BITS - 1) {
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applyChangedBits(softSerial);
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return;
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}
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if (softSerial->rxBitIndex == RX_TOTAL_BITS) {
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extractAndStoreRxByte(softSerial);
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prepareForNextRxByte(softSerial);
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}
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}
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void onSerialTimer(uint8_t portIndex, uint16_t capture)
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{
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softSerial_t *softSerial = &(softSerialPorts[portIndex]);
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@ -273,6 +295,36 @@ void onSerialTimer(uint8_t portIndex, uint16_t capture)
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processRxState(softSerial);
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}
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void onSerialRxPinChange(uint8_t portIndex, uint16_t capture)
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{
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softSerial_t *softSerial = &(softSerialPorts[portIndex]);
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if (softSerial->isSearchingForStartBit) {
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TIM_SetCounter(softSerial->rxTimerHardware->tim, 0); // synchronise bit counter
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serialICConfig(softSerial->rxTimerHardware->tim, softSerial->rxTimerHardware->channel, TIM_ICPolarity_Rising);
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softSerial->rxPinMode = RISING;
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softSerial->rxBitIndex = 0;
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softSerial->rxLastRiseAtBitIndex = 0;
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softSerial->internalRxBuffer = 0;
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softSerial->isSearchingForStartBit = false;
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return;
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}
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if (softSerial->rxPinMode == RISING) {
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softSerial->rxLastRiseAtBitIndex = softSerial->rxBitIndex;
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}
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applyChangedBits(softSerial);
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if (softSerial->rxPinMode == FALLING) {
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softSerial->rxPinMode = RISING;
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serialICConfig(softSerial->rxTimerHardware->tim, softSerial->rxTimerHardware->channel, TIM_ICPolarity_Rising);
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} else {
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softSerial->rxPinMode = FALLING;
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serialICConfig(softSerial->rxTimerHardware->tim, softSerial->rxTimerHardware->channel, TIM_ICPolarity_Falling);
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}
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}
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uint8_t softSerialTotalBytesWaiting(serialPort_t *instance)
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{
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