FlexCAN_T4 - FlexCAN for Teensy 4

[Major7]

In your program, when you want to check if errors exist, you should be able to do something like this:

void loop() {
  ... some other code ...

  static uint32_t timeout = millis();
  if ( millis() - timeout > 1000 ) {  // Check for errors every 1000 ms
    CAN_error_t err;
    if CAN0.error(err, true) {
      // the "err" structure will be populated with the current errors.
      // Second argument set to true tells the error() function to ...
      // serial.print() the current errors. 
      ... some code to handle errors here ...
    }
  }
  ... some other code ...
}

worked like a champ thank you!

[John Hasler]

Could you provide an example of how to configure and use filters with the FIFO?

[John Hasler]

Trying to use the FIFO blocks mboxes, both polled and interrupt driven.

Initialization:

void MCOUSER_ResetCommunication(void){
  int i;

  gTimCnt = GTIMCNT; // Initialize global timer
  canbus1.begin(); // Must be first JGH
  canbus1.setMaxMB(16);
  canbus1.setMBFilter(REJECT_ALL);
  canbus1.setBaudRate(1000*BAUDRATE);
  for(i = 0; i < (NR_OF_RPDOS + 2); i++) { // NMT and SDO will use the first two boxes.
    canbus1.setMB((FLEXCAN_MAILBOX)i, RX, STD);
    if(i > 1){
    canbus1.onReceive((FLEXCAN_MAILBOX)i, canbus_isr); // Get all RPDOs via interrupt. 
    canbus1.enableMBInterrupt((FLEXCAN_MAILBOX)i); 
    }
  }
  for(; i < (NR_OF_RPDOS + NR_OF_TPDOS); i++) {
    canbus1.setMB((FLEXCAN_MAILBOX)i, TX, STD);
  }
  // For sync
  #ifdef SYNC
  canbus1.setMB((FLEXCAN_MAILBOX)i, RX, STD);
  canbus1.setMBFilter((FLEXCAN_MAILBOX)i, 0x080);
  canbus1.onReceive((FLEXCAN_MAILBOX)i, canbus_sync);
  canbus1.enableMBInterrupt((FLEXCAN_MAILBOX)i);
  #endif
  // BAUDRATE,Node_ID,HEARTRATE defined at the top of this file.  JGH
  MCO_Init(BAUDRATE,Node_ID,HEARTRATE);

  // Default base receive COBs are 0x200, 0x300, 0x400, and 0x500
  // Calling MCO_InitRPDO or MCO_InitTPDO with COB-ID 0 results in default
  // RPDO1, default ID (0x200+nodeID), 4 bytes
  MCO_InitRPDO(1, 0, 4, &target_speed); 

  // RPDO2, default ID (0x300+nodeID), 4 bytes
  MCO_InitRPDO(2, 0, 4, &acceleration);
  
  //BYTE PDO_NR,  WORD CAN_ID, WORD event_time, WORD inhibit_time, BYTE len, BYTE offset
  // TPDO1, default ID (0x180+nodeID), 100ms event, 5ms inhibit, 4 bytes
  // Transmit trigger: COS (change-of-state) with 250ms inhibit time
  MCO_InitTPDO(1, 0, 0, 5, 4, &control_word);    

  // TPDO2, default ID (0x280+nodeID), 100ms event, 5ms inhibit, 4 bytes
  // Transmit trigger: COS (change-of-state) with 250ms inhibit time
  MCO_InitTPDO(2, 0, 0, 5, 4, &status_word); 

  // TPDO3, default ID (0x380+nodeID), 100ms event, 5ms inhibit, 4 bytes
  // Transmit trigger: COS with 100ms inhibit time, but if there is no COS within
  // 1000ms, message gets triggered, too
  MCO_InitTPDO(3, 0, 0, 5, 4, &target_speed);

  // TPDO4, default ID (0x480+nodeID), 100ms event, 5ms inhibit, 4 bytes
  // Transmit trigger: COS with 100ms inhibit time, but if there is no COS within
  // 1000ms, message gets triggered, too
  MCO_InitTPDO(4, 0, 0, 5, 4, &acceleration);
}


/**************************************************************************
DOES:    ISR for RPDO mailboxes. Writes message content to the correct PDO
         if the state_machine state permits. JGH
         
RETURNS: nothing
**************************************************************************/
void canbus_isr(const CAN_message_t &msg) {
  int i;
  if(gMCOConfig.heartbeat_msg.BUF[0] != 5) return; // Only receive in operational state.
  i = mbox_to_RPDO[msg.mb]; // This tells us what RPDO this mbox goes with.
  if(gRPDOConfig[i].len != msg.len) return; // Not a valid message.  Should set an error. JGH
  memcpy(gRPDOConfig[i].offset, msg.buf, gRPDOConfig[i].len);
}

Added to experiment with the FIFO:

  canbus1.enableFIFO();
  canbus1.disableFIFOInterrupt();
  canbus1.setFIFOFilter(REJECT_ALL);
  canbus1.enhanceFilter(FIFO);
  canbus1.setFIFOFilter(7, 0x123, STD);

NMTs (id 0x000) and SDOs (id 0x607) are polled with this:

BYTE MCOHW_PullMessage(CAN_MSG *pReceiveBuf){
  // pointer to a single message sized buffer to hold the received message
 
  // variable declarations
  BYTE  Length;
  BYTE  i;
  CAN_message_t msg;
  if(canbus1.readMB(msg)){
    pReceiveBuf->ID = msg.id;
    pReceiveBuf->LEN = msg.len;
    // Read data bytes and write to buffer
    for (i=0; i < msg.len; i++){
      // copy bytes
      *(BYTE *)(pReceiveBuf->BUF+i) = msg.buf[i];
    }
    return (1);
  }
  else {
    // return 0, no message received
    return (0);
  }
}

RPDOs are handled by the ISR.

The FIFO is read with this:

  CAN_message_t mesg;
  if(canbus1.readFIFO(mesg)) {
    
    Serial.print("ID "); Serial.print(mesg.id, HEX);
    Serial.print(" Filter "); Serial.print(mesg.idhit, HEX);
    Serial.print(" LEN: "); Serial.print(mesg.len);
    Serial.print(" Buffer: ");
    for ( uint8_t i = 0; i < mesg.len; i++ ) {
      Serial.print(mesg.buf[i], HEX); Serial.print(" ");
    } Serial.println();
    
  }

Everything works fine with the experimental FIFO stuff commented out. The FIFO code works as expected but when it's enabled all mboxes are blocked.
Uncommenting just the FIFO initialization blocks the mboxes.

[John Hasler]

It appears that the FIFO grabs the first 8 mboxes even if they are already allocated.

[msadie]

It appears that the FIFO grabs the first 8 mboxes even if they are already allocated.

I'm not familiar enough with implementing filters to comment, but I can confirm the FlexCAN hardware reserves MB0-MB7 when FIFO is enabled.

[Gary]

Hi

I have taken a lot of time to find a solution for my problem. I didn't find it.

I use the following filter:

Can.setFIFOFilter(0, 0x18DAF100, EXT);

How is it possible to erase this filter to get all messages? I need this filter only for a short time.

First - filter then all messages

Thanx
Gary

[msadie]

Gary, based on looking at the library, try:

Can.setFIFOFilter(Accept_All);

Also, in case you weren't aware,

Can.MailboxStatus();

is an easy way to see what's going on with the mailboxes and filters.

[Gary]

Hi msadie

Thanks a lot. This is was im looking for. Perfect...

Greetings
Gary

[mambonub5]

Hello,

I am trying to run a Teensy 4.1 with two SN65HVD230 transceivers to talk to two can networks.

I have no issues with getting CAN1 working on the 125k can network, but I cant get CAN2 to connect to my 83.3k network.

I am using the Flexcan_T4 Library.

[John Hasler]

Example:

FlexCAN State: Idle, FLT_CONF: Error Active
In GetStatus gMCOHW_status = 1
Receive errors = 0
Transmit errors = 0
error.ESR1 = 40080
FlexCAN State: Receiving, FLT_CONF: Error Active
In GetStatus gMCOHW_status = 1
Receive errors = 0
Transmit errors = 0
error.ESR1 = 40008
FlexCAN State: Idle, FLT_CONF: Error Active
In GetStatus gMCOHW_status = 1
Receive errors = 0
Transmit errors = 0
error.ESR1 = 40080

gMCOHW_status = 1 means that the error variable contained no errors.

I'm using a Teensy 3.6 running my heavily-hacked version of Microcanopen (no threads or interrupts: polling only). It is sending a TPDO every millisecond and receiving an RPDO sent by this script:

while true; do sleep .001; cansend can0 307#ffffffff; done

The bus master is canopend from Canopennode running under Linux on a pc connected to the Teensy by an 8devices USB to CAN converter.

The relevant code from the Canopen implementation:

uint8_t MCOHW_GetStatus(void) {
  CAN_error_t error;
  bool cerr = false, erpa = false, boff = false;
  int state = CO_INTERFACE_ACTIVE; // Is this the right thing to do if no errors?
  gMCOHW_status &= INIT; // Clear CAN status but leave INIT state unchanged
  if(canbus1.error(error, PRINT_ERRORS)){ // PRINT_ERRORS is defined in mco.h
    // Evidently returns zero quickly if there are no errors
    cerr = error.BIT1_ERR || error.BIT0_ERR || error.ACK_ERR || error.CRC_ERR \
      || error.FRM_ERR || error.STF_ERR;
    
    if ((error.ESR1 & 0x30) == 0x0) { // Copied from FlexCAN_T4
      erpa = 0; // Error active
      state = CO_INTERFACE_ACTIVE;
	}
    else if ((error.ESR1 & 0x30) == 0x1) { // Copied from FlexCAN_T4
      erpa = 1; // Error passive
      Serial.println("MCOHW_GetStatus: Error passive");
      state = CO_INTERFACE_LISTEN_ONLY;
    }
    else {
      boff = 1; // Bus off 
      Serial.println("MCOHW_GetStatus: Bus off");
      state = CO_INTERFACE_BUS_OFF;
    }
    gMCOHW_status |= cerr << 1;
    gMCOHW_status |= erpa << 2;
    gMCOHW_status |= error.TX_WRN << 3;
    gMCOHW_status |= error.RX_WRN << 4;
    gMCOHW_status |= boff << 7;
    Serial.print("In GetStatus gMCOHW_status = "); Serial.println(gMCOHW_status, BIN); // JGH debug
    Serial.print("Receive errors = "); Serial.println(error.RX_ERR_COUNTER);
    Serial.print("Transmit errors = "); Serial.println(error.TX_ERR_COUNTER);
    Serial.print("error.ESR1 = "); Serial.println(error.ESR1, HEX);
  }
  if((gMCOConfig.CANinterfaceState == CO_INTERFACE_BUS_OFF) && (state != CO_INTERFACE_BUS_OFF)) {
    Serial.println("MCOHW_GetStatus: Recovered from BUS_OFF");
    MCO_Handle_EMCY(CO_EMC_BUS_OFF_RECOVERED);
  }
  gMCOConfig.CANinterfaceState = state;
  return gMCOHW_status;
}

I'm using the FIFO with 8 filters allocated and with enhanceFilter(FIFO). The other mboxes are configured for transmit with TPDOs being sent via write(). It all works quite well but for this oddity.

I can provide more code, of course, but the total is about 2100 lines.

[msadie]

So canbus1.error() returns true, but once the errors print, there are none?
Am I understanding this correctly? If so, can you post the canbus.error() function?

[John Hasler]

The error() function is part of FlexCAN_T4.

FCTP_FUNC bool FCTP_OPT::error(CAN_error_t &error, bool printDetails) {
  if ( !busESR1.size() ) return 0;
  NVIC_DISABLE_IRQ(nvicIrq);
  error.ESR1 = busESR1.read();
  error.ECR = busECR.read();

  if ( (error.ESR1 & 0x400C8) == 0x40080 ) strncpy((char*)error.state, "Idle", (sizeof(error.state) - 1));
  else if ( (error.ESR1 & 0x400C8) == 0x0 ) strncpy((char*)error.state, "Not synchronized to CAN bus", (sizeof(error.state) - 1));
  else if ( (error.ESR1 & 0x400C8) == 0x40040 ) strncpy((char*)error.state, "Transmitting", (sizeof(error.state) - 1));
  else if ( (error.ESR1 & 0x400C8) == 0x40008 ) strncpy((char*)error.state, "Receiving", (sizeof(error.state) - 1));

  error.BIT1_ERR = (error.ESR1 & (1UL << 15)) ? 1 : 0;
  error.BIT0_ERR = (error.ESR1 & (1UL << 14)) ? 1 : 0;
  error.ACK_ERR = (error.ESR1 & (1UL << 13)) ? 1 : 0;
  error.CRC_ERR = (error.ESR1 & (1UL << 12)) ? 1 : 0;
  error.FRM_ERR = (error.ESR1 & (1UL << 11)) ? 1 : 0;
  error.STF_ERR = (error.ESR1 & (1UL << 10)) ? 1 : 0;
  error.TX_WRN = (error.ESR1 & (1UL << 9)) ? 1 : 0;
  error.RX_WRN = (error.ESR1 & (1UL << 8)) ? 1 : 0;

  if ( (error.ESR1 & 0x30) == 0x0 ) strncpy((char*)error.FLT_CONF, "Error Active", (sizeof(error.FLT_CONF) - 1));
  else if ( (error.ESR1 & 0x30) == 0x1 ) strncpy((char*)error.FLT_CONF, "Error Passive", (sizeof(error.FLT_CONF) - 1));
  else strncpy((char*)error.FLT_CONF, "Bus off", (sizeof(error.FLT_CONF) - 1));

  error.RX_ERR_COUNTER = (uint8_t)(error.ECR >> 8);
  error.TX_ERR_COUNTER = (uint8_t)error.ECR;

  if ( printDetails ) printErrors(error);
  NVIC_ENABLE_IRQ(nvicIrq);
  return 1;
}

[jmlima44]

Hi, I am programming two teensys 4.1 and I am using this library. While I was programming, I was trying to check if there are any CAN messages available in my loop() like this:
void loop() {
// Check if there are any CAN messages available
if (can0.available()) {
// Read the CAN message
CAN_message_t msg;
can0.read(msg);

But there is no function "available()". Is there any function that does what I want to do or if I need to use another approach what would that be?

[kd5rxt-mark]

But there is no function "available()". Is there any function that does what I want to do or if I need to use another approach what would that be?

In the Arduino IDE, take a look at the examples under File / Examples / Examples for Teensy 4.1 / FlexCAN_T4. One or more of those should get you started.

Mark J Culross
KD5RXT

[profor]

@jmlima44 mine works like this:

#include <FlexCAN_T4.h>
CAN_message_t can_fwd_car;
FlexCAN_T4<CAN2, RX_SIZE_32, TX_SIZE_32> can_master;

void setup() {
  // put your setup code here, to run once:
  can_master.begin();
  can_master.setBaudRate(125000);
}

void loop() {
  // put your main code here, to run repeatedly:
  
  if (can_master.read(can_fwd_car)) {
    
    //  do something with the data in can_fwd_car
  
  }

  //  rest of code

}