// -------------------------------------------------------------
void CAN_K2X::begin(uint32_t bitrate)
{
// segment timings from freescale loopback test
if ( 250000 == bitrate )
{
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(1)
| FLEXCAN_CTRL_PSEG1(3) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(15));
}
else if ( 500000 == bitrate )
{
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(1)
| FLEXCAN_CTRL_PSEG1(3) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(7));
}
else if ( 1000000 == bitrate )
{
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(3) | FLEXCAN_CTRL_RJW(0)
| FLEXCAN_CTRL_PSEG1(0) | FLEXCAN_CTRL_PSEG2(1) | FLEXCAN_CTRL_PRESDIV(5));
}
else // 125000
{
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(2)
| FLEXCAN_CTRL_PSEG1(3) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(31));
}
FLEXCAN0_RXMGMASK = 0;
//enable reception of all messages that fit the mask
// if (mask.extended)
// {
// FLEXCAN0_RXFGMASK = ((mask.rtr ? 1 : 0) << 31) | ((mask.extended ? 1 : 0) << 30) | ((mask.id & FLEXCAN_MB_ID_EXT_MASK) << 1);
// }
// else
// {
// FLEXCAN0_RXFGMASK = ((mask.rtr ? 1 : 0) << 31) | ((mask.extended ? 1 : 0) << 30) | (FLEXCAN_MB_ID_IDSTD(mask.id) << 1);
// }
FLEXCAN0_RXFGMASK = 0;
// start the CAN
FLEXCAN0_MCR &= ~(FLEXCAN_MCR_HALT);
// wait till exit of freeze mode
while (FLEXCAN0_MCR & FLEXCAN_MCR_FRZ_ACK);
// wait till ready
while (FLEXCAN0_MCR & FLEXCAN_MCR_NOT_RDY);
//set tx buffers to inactive
for (int i = txb; i < txb + txBuffers; i++)
{
FLEXCAN0_MBn_CS(i) = FLEXCAN_MB_CS_CODE(FLEXCAN_MB_CODE_TX_INACTIVE);
}
}
// -------------------------------------------------------------
FlexCAN::FlexCAN(uint32_t baud)
{
// set up the pins, 3=PTA12=CAN0_TX, 4=PTA13=CAN0_RX
CORE_PIN3_CONFIG = PORT_PCR_MUX(2);
CORE_PIN4_CONFIG = PORT_PCR_MUX(2);// | PORT_PCR_PE | PORT_PCR_PS;
// select clock source 16MHz xtal
OSC0_CR |= OSC_ERCLKEN;
SIM_SCGC6 |= SIM_SCGC6_FLEXCAN0;
FLEXCAN0_CTRL1 &= ~FLEXCAN_CTRL_CLK_SRC;
// enable CAN
FLEXCAN0_MCR |= FLEXCAN_MCR_FRZ;
FLEXCAN0_MCR &= ~FLEXCAN_MCR_MDIS;
while(FLEXCAN0_MCR & FLEXCAN_MCR_LPM_ACK)
;
// soft reset
FLEXCAN0_MCR ^= FLEXCAN_MCR_SOFT_RST;
while(FLEXCAN0_MCR & FLEXCAN_MCR_SOFT_RST)
;
// wait for freeze ack
while(!(FLEXCAN0_MCR & FLEXCAN_MCR_FRZ_ACK))
;
// disable self-reception
FLEXCAN0_MCR |= FLEXCAN_MCR_SRX_DIS;
//enable RX FIFO
FLEXCAN0_MCR |= FLEXCAN_MCR_FEN;
// segment splits and clock divisor based on baud rate
if ( 250000 == baud ) {
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(1)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(3));
} else if ( 500000 == baud ) {
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(1)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(1));
} else if ( 1000000 == baud ) {
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(0)
| FLEXCAN_CTRL_PSEG1(1) | FLEXCAN_CTRL_PSEG2(1) | FLEXCAN_CTRL_PRESDIV(1));
} else { // 125000
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(1)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(7));
}
// Default mask is allow everything
defaultMask.rtr = 0;
defaultMask.ext = 0;
defaultMask.id = 0;
}
// -------------------------------------------------------------
void FlexCAN::begin(uint8_t _baud)
{
// soft reset can bus
reset();
// segment splits and clock divisor based on baud rate
switch (_baud){
case (CAN_5KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(199)); // 5000 baud Prescaler -> 199 Tq -> 16
break;
case (CAN_10KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(99)); // 10000 baud Prescaler -> 99 Tq -> 16
break;
case (CAN_20KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(49)); // 20000 baud Prescaler -> 49 Tq -> 16
break;
case (CAN_25KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(39)); // 25000 baud Prescaler -> 39 Tq -> 16
break;
case (CAN_31K25BPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(31)); // 31250 baud Prescaler -> 31 Tq -> 16
break;
case (CAN_33KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(29)); // 33333 baud Prescaler -> 29 Tq -> 16
break;
case (CAN_40KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(24)); // 40000 baud Prescaler -> 24 Tq -> 16
break;
case (CAN_50KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(19)); // 50000 baud Prescaler -> 19 Tq -> 16
break;
case (CAN_80KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(1)
| FLEXCAN_CTRL_PSEG1(3) | FLEXCAN_CTRL_PSEG2(1) | FLEXCAN_CTRL_PRESDIV(19)); // 80000 baud Prescaler -> 19 !!Tq -> 10!!
break;
case (CAN_83K3BPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(11)); // 83333 baud Prescaler -> 11 Tq -> 16
break;
case (CAN_95KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(2)
| FLEXCAN_CTRL_PSEG1(4) | FLEXCAN_CTRL_PSEG2(2) | FLEXCAN_CTRL_PRESDIV(13)); // 95000 baud Prescaler -> 13 !!Tq -> 12!!
break;
case (CAN_100KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(9)); // 100000 baud Prescaler -> 9 Tq -> 16
break;
case (CAN_125KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(7)); // 125000 baud Prescaler -> 7 Tq -> 16
break;
case (CAN_200KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(4)); // 200000 baud Prescaler -> 4 Tq -> 16
break;
case (CAN_250KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(3)); // 250000 baud Prescaler -> 3 Tq -> 16
break;
case (CAN_500KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(1)); // 500000 baud Prescaler -> 1 Tq -> 16
break;
case (CAN_666KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(2)
| FLEXCAN_CTRL_PSEG1(4) | FLEXCAN_CTRL_PSEG2(2) | FLEXCAN_CTRL_PRESDIV(1)); // 666666 baud Prescaler -> 1 !!Tq -> 12!!
break;
case (CAN_1000KBPS):
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(3)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(0)); // 100000 baud Prescaler -> 0 Tq -> 16
break;
default: // 125000
FLEXCAN0_CTRL1 = (FLEXCAN_CTRL_PROPSEG(2) | FLEXCAN_CTRL_RJW(2)
| FLEXCAN_CTRL_PSEG1(7) | FLEXCAN_CTRL_PSEG2(3) | FLEXCAN_CTRL_PRESDIV(7)); // 125000 baud Prescaler -> 7 Tq -> 16
break;
}
//enable reception of all messages
FLEXCAN0_RXMGMASK = 0;
FLEXCAN0_RXFGMASK = ((defaultMask.rtr?1:0) << 31) | ((defaultMask.ext?1:0) << 30) | (FLEXCAN_MB_ID_IDSTD(defaultMask.id) << 1);
// start the CAN
FLEXCAN0_MCR &= ~(FLEXCAN_MCR_HALT);
// wait till exit of freeze mode
while(FLEXCAN0_MCR & FLEXCAN_MCR_FRZ_ACK);
// wait till ready
while(FLEXCAN0_MCR & FLEXCAN_MCR_NOT_RDY);
//set tx buffers to inactive
for (int i = txb; i < txb + txBuffers; i++) {
FLEXCAN0_MBn_CS(i) = FLEXCAN_MB_CS_CODE(FLEXCAN_MB_CODE_TX_INACTIVE);
}
}
void FlexCAN::begin (uint32_t baud, const CAN_filter_t &mask, uint8_t txAlt, uint8_t rxAlt)
{
// set up the pins
if (flexcanBase == FLEXCAN0_BASE) {
dbg_println ("Begin setup of CAN0");
#if defined(__MK66FX1M0__) || defined(__MK64FX512__)
// 3=PTA12=CAN0_TX, 4=PTA13=CAN0_RX (default)
// 29=PTB18=CAN0_TX, 30=PTB19=CAN0_RX (alternative)
if (txAlt == 1)
CORE_PIN29_CONFIG = PORT_PCR_MUX(2);
else
CORE_PIN3_CONFIG = PORT_PCR_MUX(2);
// | PORT_PCR_PE | PORT_PCR_PS;
if (rxAlt == 1)
CORE_PIN30_CONFIG = PORT_PCR_MUX(2);
else
CORE_PIN4_CONFIG = PORT_PCR_MUX(2);
#else
// 3=PTA12=CAN0_TX, 4=PTA13=CAN0_RX (default)
// 32=PTB18=CAN0_TX, 25=PTB19=CAN0_RX (alternative)
if (txAlt == 1)
CORE_PIN32_CONFIG = PORT_PCR_MUX(2);
else
CORE_PIN3_CONFIG = PORT_PCR_MUX(2);
// | PORT_PCR_PE | PORT_PCR_PS;
if (rxAlt == 1)
CORE_PIN25_CONFIG = PORT_PCR_MUX(2);
else
CORE_PIN4_CONFIG = PORT_PCR_MUX(2);
#endif
}
#if defined(INCLUDE_FLEXCAN_CAN1)
else if (flexcanBase == FLEXCAN1_BASE) {
dbg_println("Begin setup of CAN1");
// 33=PTE24=CAN1_TX, 34=PTE25=CAN1_RX (default)
// NOTE: Alternative CAN1 pins are not broken out on Teensy 3.6
CORE_PIN33_CONFIG = PORT_PCR_MUX(2);
CORE_PIN34_CONFIG = PORT_PCR_MUX(2);// | PORT_PCR_PE | PORT_PCR_PS;
}
#endif
// select clock source 16MHz xtal
OSC0_CR |= OSC_ERCLKEN;
if (flexcanBase == FLEXCAN0_BASE) {
SIM_SCGC6 |= SIM_SCGC6_FLEXCAN0;
#if defined(INCLUDE_FLEXCAN_CAN1)
} else if (flexcanBase == FLEXCAN1_BASE) {
SIM_SCGC3 |= SIM_SCGC3_FLEXCAN1;
#endif
}
FLEXCANb_CTRL1(flexcanBase) &= ~FLEXCAN_CTRL_CLK_SRC;
// enable CAN
FLEXCANb_MCR (flexcanBase) |= FLEXCAN_MCR_FRZ;
FLEXCANb_MCR (flexcanBase) &= ~FLEXCAN_MCR_MDIS;
while (FLEXCANb_MCR(flexcanBase) & FLEXCAN_MCR_LPM_ACK)
;
// soft reset
FLEXCANb_MCR (flexcanBase) ^= FLEXCAN_MCR_SOFT_RST;
while (FLEXCANb_MCR (flexcanBase) & FLEXCAN_MCR_SOFT_RST)
;
// wait for freeze ack
while (!(FLEXCANb_MCR(flexcanBase) & FLEXCAN_MCR_FRZ_ACK))
;
// disable self-reception
FLEXCANb_MCR (flexcanBase) |= FLEXCAN_MCR_SRX_DIS;
/*
now using a system that tries to automatically generate a viable baud setting.
Bear these things in mind:
- The master clock is 16Mhz
- You can freely divide it by anything from 1 to 256
- There is always a start bit (+1)
- The rest (prop, seg1, seg2) are specified 1 less than their actual value (aka +1)
- This gives the low end bit timing as 5 (1 + 1 + 2 + 1) and the high end 25 (1 + 8 + 8 + 8)
A worked example: 16Mhz clock, divisor = 19+1, bit values add up to 16 = 16Mhz / 20 / 16 = 50k baud
*/
// have to find a divisor that ends up as close to the target baud as possible while keeping the end result between 5 and 25
uint32_t divisor = 0;
uint32_t bestDivisor = 0;
uint32_t result = 16000000 / baud / (divisor + 1);
int error = baud - (16000000 / (result * (divisor + 1)));
int bestError = error;
while (result > 5) {
divisor++;
result = 16000000 / baud / (divisor + 1);
if (result <= 25) {
error = baud - (16000000 / (result * (divisor + 1)));
if (error < 0)
error *= -1;
// if this error is better than we've ever seen then use it - it's the best option
if (error < bestError) {
bestError = error;
bestDivisor = divisor;
}
// If this is equal to a previously good option then
// switch to it but only if the bit time result was in the middle of the range
// this biases the output to use the middle of the range all things being equal
// Otherwise it might try to use a higher divisor and smaller values for prop, seg1, seg2
// and that's not necessarily the best idea.
if ((error == bestError) && (result > 11) && (result < 19)) {
bestError = error;
bestDivisor = divisor;
}
}
}
divisor = bestDivisor;
result = 16000000 / baud / (divisor + 1);
if ((result < 5) || (result > 25) || (bestError > 300)) {
Serial.println ("Abort in CAN begin. Couldn't find a suitable baud config!");
return;
}
result -= 5; // the bitTimingTable is offset by 5 since there was no reason to store bit timings for invalid numbers
uint8_t propSeg = bitTimingTable[result][0];
uint8_t pSeg1 = bitTimingTable[result][1];
uint8_t pSeg2 = bitTimingTable[result][2];
// baud rate debug information
dbg_println ("Bit time values:");
dbg_print ("Prop = ");
dbg_println (propSeg + 1);
dbg_print ("Seg1 = ");
dbg_println (pSeg1 + 1);
dbg_print ("Seg2 = ");
dbg_println (pSeg2 + 1);
dbg_print ("Divisor = ");
dbg_println (divisor + 1);
FLEXCANb_CTRL1 (flexcanBase) = (FLEXCAN_CTRL_PROPSEG(propSeg) | FLEXCAN_CTRL_RJW(1) | FLEXCAN_CTRL_ERR_MSK |
FLEXCAN_CTRL_PSEG1(pSeg1) | FLEXCAN_CTRL_PSEG2(pSeg2) | FLEXCAN_CTRL_PRESDIV(divisor));
// enable per-mailbox filtering
FLEXCANb_MCR(flexcanBase) |= FLEXCAN_MCR_IRMQ;
// now have to set mask and filter for all the Rx mailboxes or they won't receive anything by default.
for (uint8_t c = 0; c < NUM_MAILBOXES - numTxMailboxes; c++) {
setMask (0, c);
setFilter (mask, c);
}
// start the CAN
FLEXCANb_MCR(flexcanBase) &= ~(FLEXCAN_MCR_HALT);
// wait till exit of freeze mode
while (FLEXCANb_MCR(flexcanBase) & FLEXCAN_MCR_FRZ_ACK)
;
// wait till ready
while (FLEXCANb_MCR(flexcanBase) & FLEXCAN_MCR_NOT_RDY)
;
setNumTxBoxes (2);
#if defined(__MK20DX256__)
NVIC_SET_PRIORITY (IRQ_CAN_MESSAGE, IRQ_PRIORITY);
NVIC_ENABLE_IRQ (IRQ_CAN_MESSAGE);
#elif defined(__MK64FX512__)
NVIC_SET_PRIORITY (IRQ_CAN0_MESSAGE, IRQ_PRIORITY);
NVIC_ENABLE_IRQ (IRQ_CAN0_MESSAGE);
#elif defined(__MK66FX1M0__)
if (flexcanBase == FLEXCAN0_BASE) {
NVIC_SET_PRIORITY (IRQ_CAN0_MESSAGE, IRQ_PRIORITY);
NVIC_ENABLE_IRQ (IRQ_CAN0_MESSAGE);
} else {
NVIC_SET_PRIORITY (IRQ_CAN1_MESSAGE, IRQ_PRIORITY);
NVIC_ENABLE_IRQ (IRQ_CAN1_MESSAGE);
}
#endif
// enable interrupt masks for all 16 mailboxes
FLEXCANb_IMASK1 (flexcanBase) = 0xFFFF;
dbg_println ("CAN initialized properly");
}
