petrkr/ZPA_elektromer_UARTtest
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BCC Checksum calculation

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This commit is contained in:
Petr Kracík 2019-06-12 01:04:16 +02:00
parent f2b578a708
commit dd7e55d7a6
1 changed files with 26 additions and 2 deletions
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28
ZPA_elektromer_UARTtest.ino
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@ -78,8 +78,17 @@ void setup() {
} }
// BCC is calculated as follows (source https://github.com/lvzon/dsmr-p1-parser/blob/master/doc/IEC-62056-21-notes.md):
// The BCC is calculated over the bytes after STX up to and including the ETX byte
// To calculate this BCC, take the first byte XOR 0xff
// XOR this value with the second byte, and so forth up to and including the last byte (include 0x03 ETX !!),
// and XOR the final value with 0xff.
bool firstBCCbyte = false;
uint8_t localBCC = 0;
void loop() { void loop() {
// put your main code here, to run repeatedly:
ArduinoOTA.handle(); ArduinoOTA.handle();
@ -88,19 +97,34 @@ void loop() {
if (r == 0x02) { if (r == 0x02) {
Serial.print("<STX>"); Serial.print("<STX>");
firstBCCbyte = true;
uint8_t localBCC = 0;
return; return;
} }
if (r == 0x03) { if (r == 0x03) {
Serial.println("<ETX>"); Serial.println("<ETX>");
Serial.print("Checksum <BCC>: "); Serial.print("Checksum <BCC>: ");
Serial.println(Serial2.read()); Serial.print(Serial2.read());
Serial.println();
Serial.print("Calculated <BCC>: ");
localBCC = localBCC ^ 0x03;
localBCC = localBCC ^ 0xFF;
Serial.print(localBCC);
Serial.println();
Serial.println(); Serial.println();
Serial.println("Changing back baudrate to 300"); Serial.println("Changing back baudrate to 300");
Serial2.updateBaudRate(300); Serial2.updateBaudRate(300);
return; return;
} }
// Calculate BCC checksum
if (firstBCCbyte) {
firstBCCbyte = false;
localBCC = r ^ 0xFF;
} else {
localBCC = localBCC ^ r;
}
Serial.write(r); Serial.write(r);
} }