Oulalaa
commented
1 year ago Hi, looks like I have located the problem. When I set the ext bit to false, the RTR frame can be received. So It seems like the RTR bit and the EXT bit can't be true in the same message. Which means that an extended RTR frame can not be received. I don't know why but I hope it can be fixed if possible.
My question is, is there a way to receive an extended RTR frame? Here is my test code based on the loopback example.
// ACAN2515 RTR Demo in loopback mode
//——————————————————————————————————————————————————————————————————————————————
#include <ACAN2515.h>
//——————————————————————————————————————————————————————————————————————————————
// MCP2515 connections:
// - standard SPI pins for SCK, MOSI and MISO
// - a digital output for CS
// - interrupt input pin for INT
//——————————————————————————————————————————————————————————————————————————————
// If you use CAN-BUS shield (http://wiki.seeedstudio.com/CAN-BUS_Shield_V2.0/) with Arduino Uno,
// use B connections for MISO, MOSI, SCK, #9 or #10 for CS (as you want),
// #2 or #3 for INT (as you want).
//——————————————————————————————————————————————————————————————————————————————
// Error codes and possible causes:
// In case you see "Configuration error 0x1", the Arduino doesn't communicate
// with the 2515. You will get this error if there is no CAN shield or if
// the CS pin is incorrect.
// In case you see succes up to "Sent: 17" and from then on "Send failure":
// There is a problem with the interrupt. Check if correct pin is configured
//——————————————————————————————————————————————————————————————————————————————
static const byte MCP2515_CS = 10 ; // CS input of MCP2515 (adapt to your design)
static const byte MCP2515_INT = 3 ; // INT output of MCP2515 (adapt to your design)
//——————————————————————————————————————————————————————————————————————————————
// MCP2515 Driver object
//——————————————————————————————————————————————————————————————————————————————
ACAN2515 can (MCP2515_CS, SPI, MCP2515_INT) ;
//——————————————————————————————————————————————————————————————————————————————
// MCP2515 Quartz: adapt to your design
//——————————————————————————————————————————————————————————————————————————————
static const uint32_t QUARTZ_FREQUENCY = 16UL * 1000UL * 1000UL ; // 16 MHz
//——————————————————————————————————————————————————————————————————————————————
// SETUP
//——————————————————————————————————————————————————————————————————————————————
void setup () {
//--- Switch on builtin led
pinMode (LED_BUILTIN, OUTPUT) ;
digitalWrite (LED_BUILTIN, HIGH) ;
//--- Start serial
Serial.begin (38400) ;
//--- Wait for serial (blink led at 10 Hz during waiting)
while (!Serial) {
delay (50) ;
digitalWrite (LED_BUILTIN, !digitalRead (LED_BUILTIN)) ;
}
//--- Begin SPI
SPI.begin () ;
//--- Configure ACAN2515
Serial.println ("Configure ACAN2515") ;
ACAN2515Settings settings (QUARTZ_FREQUENCY, 125UL * 1000UL) ; // CAN bit rate 125 kb/s
settings.mRequestedMode = ACAN2515Settings::LoopBackMode ; // Select loopback mode
const uint16_t errorCode = can.begin (settings, [] { can.isr () ; }) ;
if (errorCode == 0) {
Serial.print ("Bit Rate prescaler: ") ;
Serial.println (settings.mBitRatePrescaler) ;
Serial.print ("Propagation Segment: ") ;
Serial.println (settings.mPropagationSegment) ;
Serial.print ("Phase segment 1: ") ;
Serial.println (settings.mPhaseSegment1) ;
Serial.print ("Phase segment 2: ") ;
Serial.println (settings.mPhaseSegment2) ;
Serial.print ("SJW: ") ;
Serial.println (settings.mSJW) ;
Serial.print ("Triple Sampling: ") ;
Serial.println (settings.mTripleSampling ? "yes" : "no") ;
Serial.print ("Actual bit rate: ") ;
Serial.print (settings.actualBitRate ()) ;
Serial.println (" bit/s") ;
Serial.print ("Exact bit rate ? ") ;
Serial.println (settings.exactBitRate () ? "yes" : "no") ;
Serial.print ("Sample point: ") ;
Serial.print (settings.samplePointFromBitStart ()) ;
Serial.println ("%") ;
}else{
Serial.print ("Configuration error 0x") ;
Serial.println (errorCode, HEX) ;
}
}
//----------------------------------------------------------------------------------------------------------------------
static uint32_t gBlinkLedDate = 0 ;
static uint32_t gReceivedFrameCount = 0 ;
static uint32_t gSentFrameCount = 0 ;
//——————————————————————————————————————————————————————————————————————————————
void loop () {
CANMessage frame ;
CANMessage inmsg ;
frame.rtr = true;
frame.ext = true;//commented to print the received frame RTR
frame.id = 0x112;
if (gBlinkLedDate < millis ()) {
gBlinkLedDate += 2000 ;
digitalWrite (LED_BUILTIN, !digitalRead (LED_BUILTIN)) ;
const bool ok = can.tryToSend (frame) ;
if (ok) {
gSentFrameCount += 1 ;
Serial.print ("Sent: ") ;
Serial.println (gSentFrameCount) ;
Serial.print ("Sent RTR bit: ") ;
Serial.println (frame.rtr) ;
}else{
Serial.println ("Send failure") ;
}
}
if (can.available ()) {
can.receive (inmsg) ;
gReceivedFrameCount ++ ;
Serial.print ("Received ID: ") ;
Serial.println (inmsg.id) ;
Serial.print ("Received RTR bit: ") ;
Serial.println (inmsg.rtr) ;
}
}
//——————————————————————————————————————————————————————————————————————————————```
pierremolinaro
Hi, Pierre
I got a question on RTR frames. I want to tell apart whether a received message is a RTR frame by the value of RTR bit. But when I sent a RTR frame with RTR bit == 1, and tried to use a filter to receive it, in the end the RTR bit of this received message becomes 0.
Then I notice that in the ACAN2515 document, section 9.2 on page 20, it says :
Does that mean a filter will set the RTR bit to 0 automatically, even I set it to 1 before sending? If that is true, to tell apart a RTR frame, do I have to manually dispatch the received messages as decribed in section 8 on page 18?