I am designing a master-slave LoRa link between two Arduino Pro Minis. The goal is to control a car heater a few hundred meters from my home. The master sends a command to the slave as needed. The slave acknowledges the command.
If no ACK is received in 5 sec the command is resent. In addition to this the master queries the slave every minute to verify the link.
This library is used to control the DRF1278F
I presume that a receive callback or a call to LoRa.parsePacket() returns either nothing or a complete packet, so I do not ever have to handle partial packets.
Chinese Arduino Pro Mini 3.3V 8MHz boards are used.
I am using a module DRF1278F module which contains an RFIC SX1278
Connections
Arduino --> LoRa module
----------------------------------
SS 10 --> NSEL 10k pullup to Vcc
SCK 13 --> SCK
MISO 12 --> SDO 100k pulldown to GND
MOSI 11 --> SDI
INT 3 --> IO0
RST 6 --> RST
The device is built on a piece of PCB acting as a ground plane, all GND connections are done to this plane.
It is constructed with short direct wiring.
Problem.
After several hours of operation either the master or the slave sort of hangs up. No radio operations any more. There is activity on the SPI but very different to normal operation. I have tested for weeks and not yet survived for one night.
Pushing the reset button does not restore operations. Removing 3.3V power always restore normal operation, even a very brief short circuit of 3.3V. There is no need to rest in power down, so probably not an overheat issue.
It can be either the master or the slave end that hangs up. Power cycling only the hung up unit will restore communications. My simple protocol will then resyncronize itself and continue running.
The arduino watch dog timer is activated, however it does not trigger when the hangup occurs as the arduino program loop still runs.
Things tested.
The 3.3 V supply has less than 50mV p-p ripple as checked with an oscilloscope set to infinite persistence for 8 hours, while a hangup occurred.
The interface can be run either polled or interrupt driven, no difference. No String objects are used.
Using different Vcc like 3.0V and 3.6V makes no difference.
Extra Vcc decoupling made no improvement.
Lowering SPI speed from 8MHz to 4MHz made no difference.
Removed Arduino LED on pin 13.
My problem symptoms are similar to this old question
What can I do to resolve this issue?
Slave code:
/*
Relay controller, remote end of link
*/
#include <SPI.h>
#include <LoRa.h>
#include <avr/wdt.h>
//#define TTT
#define csPin 10
#define resetPin 6
#define irqPin 3 // must be a hardware interrupt pin
#define myLED 8
#define GNDRET 7
#define powerPin 9
unsigned long LEDtime;
const unsigned long LEDonTime = 500;
char outgoing[40];
byte msgCount = 0;
unsigned long lastLoopTime = 0;
unsigned long heaterStarted = 0l;
const unsigned long heaterTime = 60 * 60 * 1000L; // One hour in ms
unsigned interval = 2000;
int temp = 2310;
byte localAddress = 0x11, destination = 0xAA;
unsigned long ttt;
volatile char incoming[40];
volatile int recipient;
volatile byte sender, incomingMsgId,
incomingLength, gotMsg, ovrn;
void setup()
{
Serial.begin(9600);
while (!Serial);
pinMode(myLED, OUTPUT);
digitalWrite(myLED, LOW);
pinMode(GNDRET, OUTPUT);
digitalWrite(GNDRET, LOW);
pinMode(powerPin, OUTPUT);
digitalWrite(powerPin, LOW);
Serial.println("LoRa Switch 0.1");
LoRa.setPins(csPin, resetPin, irqPin);
/*
LoRa.setTxPower(10);
LoRa.setSpreadingFactor(12);
LoRa.setCodingRate4(8);
LoRa.setSPIFrequency(4E6);
LoRa.enableCrc();
*/
wdt_enable(WDTO_1S);
if (!LoRa.begin(433E6))
{
Serial.println("LoRa init failed. Check your connections.");
{
// blinking in panic
LEDtime = millis();
while (millis() - LEDtime < 75)
{
digitalWrite(myLED, HIGH);
}
while (millis() - LEDtime < 150)
{
digitalWrite(myLED, LOW);
}
}
}
LoRa.onReceive(onReceive); // Assign callback
LoRa.receive();
Serial.println("LoRa init succeeded.");
}
void loop()
{
if (millis() - lastLoopTime > 1000)
{
// Once per second loop
lastLoopTime = millis();
}
// onReceive(LoRa.parsePacket()); // Polling
if (gotMsg) // Flag from CallBack routine
{
digitalWrite(myLED, HIGH);
LEDtime = millis();
#ifdef TTT
Serial.print("Received from: 0x");
Serial.println(sender, HEX);
Serial.print("Sent to: 0x");
Serial.println(recipient, HEX);
Serial.print("Message ID: ");
Serial.println(incomingMsgId);
Serial.print("Message length: ");
Serial.println(incomingLength);
Serial.print("Message: <<");
for (int i = 0; incoming[i] != 0; i++)
Serial.write(incoming[i]);
Serial.println(">>");
Serial.print("RSSI: ");
Serial.println(LoRa.packetRssi());
Serial.print("Snr: ");
Serial.println(LoRa.packetSnr());
Serial.println();
#endif
// Command processing
if (incomingLength == 4)
{
// Start heater, it will either timeout or be stopped by a message
if ((byte)incoming[0] == 0x55 && (byte)incoming[1] == 0xAA)
{
Serial.println("Set on");
digitalWrite(powerPin, HIGH);
heaterStarted = millis();
}
if ((byte)incoming[0] == 0xCC && (byte)incoming[1] == 0x99) // Stop heater
{
Serial.println("Set off");
digitalWrite(powerPin, LOW);
heaterStarted = 0L;
}
// Build ack answer
if (heaterStarted > 0L)
{
// Compute session time in minutes
ttt = millis() - heaterStarted;
ttt /= (1000L * 60L); // minutes since start
}
else
ttt = 0L;
outgoing[0] = (heaterStarted > 0L) ? 'T' : 'F'; // Heater state
snprintf(outgoing + 1, 30, "%3lu", ttt);
incoming[0] = 0; // We are done, clear flags
gotMsg = 0;
sendAck(outgoing);
}
LoRa.receive();
}
if (LEDtime) // LED timeout
{
if (millis() - LEDtime > LEDonTime)
{
digitalWrite(myLED, LOW);
LEDtime = 0;
}
}
if (heaterStarted) // Heater timeout
{
if (millis() - heaterStarted > heaterTime)
{
digitalWrite(powerPin, LOW);
heaterStarted = 0L;
}
}
wdt_reset();
// END of loop
}
void sendMessage(char *outgoing)
{
LoRa.beginPacket(); // start packet
LoRa.write(destination); // add destination address
LoRa.write(localAddress); // add sender address
LoRa.write(msgCount++); // add message ID
LoRa.write(bsize(outgoing)); // add payload length
LoRa.print(outgoing); // add payload
LoRa.endPacket(); // finish packet and send it
}
void sendAck(char *outgoing)
{
Serial.println("Send ACK");
LoRa.beginPacket();
LoRa.write(destination);
LoRa.write(localAddress);
LoRa.write(incomingMsgId); // report ID
LoRa.write(bsize(outgoing)); // add payload length
LoRa.print(outgoing); // add payload
LoRa.endPacket();
}
byte bsize(char *ooo)
{
byte i = 0;
while (ooo[i++]);
return i - 1;
}
byte bsize(volatile char *oo)
{
return bsize((volatile char *)oo);
}
byte insptr;
void onReceive(int packetSize) // has to be a non blocking function
{
if (packetSize == 0) return; // if there's no packet, return
if (gotMsg) ovrn = true; // gotMsg should be reset by consumer by now
// read packet header bytes:
recipient = LoRa.read(); // recipient address
sender = LoRa.read(); // sender address
incomingMsgId = LoRa.read(); // incoming msg ID
incomingLength = LoRa.read(); // incoming msg length
insptr = 0;
while (LoRa.available())
{
if (insptr < 38)
incoming[insptr++] = (char)LoRa.read();
else
LoRa.read(); // Flush
}
incoming[insptr] = 0; // End of C string
gotMsg = true;
}
/*
void setTxPower(int level, int outputPin = PA_OUTPUT_PA_BOOST_PIN);
void setFrequency(long frequency);
void setSpreadingFactor(int sf);
void setSignalBandwidth(long sbw);
void setCodingRate4(int denominator);
void setPreambleLength(long length);
void setSyncWord(int sw);
void enableCrc();
void disableCrc();
*/
Master code:
/*
Relay controller, Controller and GUI base
*/
#include <SPI.h>
#include <LoRa.h>
#include <avr/wdt.h>
#define TTT
#define csPin 10
#define resetPin 6
#define irqPin 3 // must be a hardware interrupt pin
#define ackLED 9
#define LEDGND 8
#define remoteLED 7
unsigned long LEDtime;
const unsigned long LEDonTime = 500;
char outgoing[40];
byte msgSequ = 0, mincnt, ack_TO;
unsigned long lastLoopTime = 0;
unsigned interval = 2000;
byte localAddress = 0xAA, destination = 0x11;
unsigned long ttt;
volatile char incoming[40];
volatile int recipient;
volatile byte sender, incomingMsgId, incomingLength, isACKed, gotMsg, ovrn;
char cc;
void setup()
{
Serial.begin(9600);
while (!Serial);
pinMode(ackLED, OUTPUT);
digitalWrite(ackLED, LOW);
pinMode(remoteLED, OUTPUT);
digitalWrite(remoteLED, LOW);
pinMode(LEDGND, OUTPUT);
digitalWrite(LEDGND, LOW);
isACKed = 1;
Serial.println("LoRa Master 0.1");
LoRa.setPins(csPin, resetPin, irqPin);
/* no specials
LoRa.setTxPower(10);
LoRa.setSPIFrequency(4E6);
LoRa.setSpreadingFactor(12);
LoRa.setCodingRate4(8);
LoRa.enableCrc();
*/
wdt_enable(WDTO_1S);
if (!LoRa.begin(433E6))
{
Serial.println("LoRa init failed. Check your connections.");
{
// blinking in panic
LEDtime = millis();
while (millis() - LEDtime < 75)
{
digitalWrite(ackLED, HIGH);
}
while (millis() - LEDtime < 150)
{
digitalWrite(ackLED, LOW);
}
}
}
LoRa.onReceive(onReceive); // Assign callback
LoRa.receive();
Serial.println("LoRa init succeeded.");
}
void loop()
{
digitalWrite(ackLED, isACKed == 0);
if (millis() - lastLoopTime > 1000)
{
// Once per second loop
lastLoopTime = millis();
if (isACKed == 0)
{
if (ack_TO++ > 5)
{
sendMessage(outgoing); // Resend
LoRa.receive();
ack_TO = 0;
Serial.println("Resend...");
}
}
if (mincnt++ > 60)
{
// Once per minute loop
mincnt = 0;
if (isACKed) // Free to ask
{
// Heartbeat
cmdAsk();
isACKed = 0;
}
}
}
if ((cc = Serial.read()) > 0) // Test version, cmd
{
if (cc == '1')
{
cmdOn();
isACKed = 0;
}
else if (cc == '0')
{
cmdOff();
isACKed = 0;
}
else if (cc == 'Q')
{
cmdAsk();
isACKed = 0;
}
}
// onReceive(LoRa.parsePacket()); // Polling
if (gotMsg) // Flag from onReceive routine
{
#ifdef TTT
Serial.print("Received from: 0x");
Serial.println(sender, HEX);
Serial.print("Sent to: 0x");
Serial.println(recipient, HEX);
Serial.print("Message ID: ");
Serial.println(incomingMsgId);
Serial.print("Message length: ");
Serial.println(incomingLength);
Serial.print("Message: <<");
for (int i = 0; incoming[i] != 0; i++)
Serial.write(incoming[i]);
Serial.println(">>");
Serial.print("RSSI: ");
Serial.println(LoRa.packetRssi());
Serial.print("Snr: ");
Serial.println(LoRa.packetSnr());
Serial.println();
#endif
// Command processing
if (incomingLength == 4)
if (incomingMsgId == msgSequ - 1) // Ack is on last sent
{
if (incoming[0] == 'T') digitalWrite(remoteLED, HIGH);
if (incoming[0] == 'F') digitalWrite(remoteLED, LOW);
isACKed = 1;
}
incoming[0] = 0; // Message is processed, clear flags
gotMsg = 0;
}
if (LEDtime) // LED timeout
{
if (millis() - LEDtime > LEDonTime)
{
LEDtime = 0;
}
}
wdt_reset();
} // END of loop
void cmdOn()
{
outgoing[0] = 0x55; // Heater on
outgoing[1] = 0xAA;
outgoing[2] = 'X';
outgoing[3] = 'Y';
sendMessage(outgoing);
LoRa.receive();
}
void cmdOff()
{
outgoing[0] = 0xCC; // Heater off
outgoing[1] = 0x99;
outgoing[2] = 'A';
outgoing[3] = 'B';
sendMessage(outgoing);
LoRa.receive();
}
void cmdAsk()
{
outgoing[0] = 0x0F;
outgoing[1] = 0xF0;
outgoing[2] = '7';
outgoing[3] = '7';
sendMessage(outgoing);
LoRa.receive();
}
void sendMessage(char *outgoing)
{
LoRa.beginPacket(); // start packet
LoRa.write(destination); // add destination address
LoRa.write(localAddress); // add sender address
LoRa.write(msgSequ++); // add message ID
LoRa.write(bsize(outgoing)); // add payload length
LoRa.print(outgoing); // add payload
LoRa.endPacket(); // finish packet and send it
}
byte bsize(char *ooo)
{
byte i = 0;
while (ooo[i++]);
return i - 1;
}
byte bsize(volatile char *oo)
{
return bsize((volatile char *)oo);
}
unsigned char insptr;
void onReceive(int packetSize) // is a non blocking function
{
if (packetSize == 0) return; // if there's no packet, return
if (gotMsg) ovrn = true; // gotMsg should be reset by consumer by now
// read packet header bytes:
recipient = LoRa.read(); // recipient address
sender = LoRa.read(); // sender address
incomingMsgId = LoRa.read(); // incoming msg ID
incomingLength = LoRa.read(); // incoming msg length
insptr = 0;
while (LoRa.available())
{
if (insptr < 38)
incoming[insptr++] = (char)LoRa.read();
else
LoRa.read(); // Flush
}
incoming[insptr] = 0;
gotMsg = true;
}
/*
void setTxPower(int level, int outputPin = PA_OUTPUT_PA_BOOST_PIN);
void setFrequency(long frequency);
void setSpreadingFactor(int sf);
void setSignalBandwidth(long sbw);
void setCodingRate4(int denominator);
void setPreambleLength(long length);
void setSyncWord(int sw);
void enableCrc();
void disableCrc();
RSSI always a value between -30 ( very close) and - 120
SNR 0 is noise floor… max = 10
*/
