Hi guys,
I am very new to Arduino and this is my very first topic here. I am currently working on car's CAN BUS (500,000bps) communication in order to read and translate the CAN message real time. The UNO together with MCP2515 are connected to the car OBD2 port in order to sniff all supported PID data and the available output are now printed out and it looks promising enough (attached picture). However, I experienced frequent data loss, even though there is the delay of 5 seconds to read the next loop of data. I did try searching but never get any closer to the proper solution. Is this situation is called either Race Condition or data overflow? or I have to take a look at buffer size of transmitted data?
All source file and sketch are referred to GitHub - sandeepmistry/arduino-OBD2: An Arduino library for reading OBD-II data from your car over CAN bus.
Here is the sketch I used (libraries\OBD2-0.0.1\examples\OBD2_01_SupportedPIDs);
#include <CAN.h> // the OBD2 library depends on the CAN library
#include <OBD2.h>
void setup() {
Serial.begin(9600);
while (!Serial);
Serial.println(F("OBD2 data printer"));
while (true) {
Serial.print(F("Attempting to connect to OBD2 CAN bus ... "));
if (!OBD2.begin()) {
Serial.println(F("failed!"));
delay(1000);
} else {
Serial.println(F("success"));
break;
}
}
Serial.println();
Serial.print("VIN = ");
Serial.println(OBD2.vinRead());
Serial.print("ECU Name = ");
Serial.println(OBD2.ecuNameRead());
Serial.println();
}
void loop() {
// loop through PIDs 0 to 95, reading and printing the values
for (int pid = 0; pid < 96; pid++) {
processPid(pid);
}
Serial.println();
// wait 5 seconds before next run
delay(5000);
}
void processPid(int pid) {
if (!OBD2.pidSupported(pid)) {
// PID not supported, continue to next one ...
return;
}
// print PID name
Serial.print(OBD2.pidName(pid));
Serial.print(F(" = "));
if (OBD2.pidValueRaw(pid)) {
// read the raw PID value
unsigned long pidRawValue = OBD2.pidReadRaw(pid);
Serial.print(F("0x"));
Serial.print(pidRawValue, HEX);
} else {
// read the PID value
float pidValue = OBD2.pidRead(pid);
if (isnan(pidValue)) {
Serial.print("error");
} else {
// print value with units
Serial.print(pidValue);
Serial.print(F(" "));
Serial.print(OBD2.pidUnits(pid));
}
}
Serial.println();
}
