Raspberry Pi Pico - Multi Core

Projects Programming
1

Hello,

I am attempting to use both cores of a Raspberry Pi Pico W:

Core 0 - WiFi and MQTT

Core 1 - Serial1 to read a serial data stream and decode it, then making it available for publication by MQTT on Core 0.

However, I end up with the Pico crashing when I attempt to pause Core 0 from Core 1.

I have simplified my attempt to date in the following test code (which excludes any of the WiFi/MQTT/actual Serial1 stuff):

  1. When I simply run the risk of having Core 0 and Core 1 clash over the "stringCore1" variable (Core 1 writes to this variable; Core 0 reads it and nulls it) I have yet to have any crashes.

  2. When I uncommenting out the "//rp2040.idleOtherCore();" and "//rp2040.resumeOtherCore();" code, the Pico regularly crashes (in minutes, sometimes seconds).

Any ideas? Is it 'safe' to simply not worry about pausing Core 1 from Core 0?!?

#define DEBUG       // DEBUG allows for debugging information to be printed

#ifdef DEBUG
  #define VERBOSE   // If VERBOSE, DEBUG information includes 'Starting function()' and 'function() completed'
#endif


// heartBeat flashes onboard LED to show Pico W is operating
unsigned long heartBeatTime = millis(); // Time to make onboard LED flash when running
bool heartBeatState = true; // Onboard LED state


#ifdef DEBUG
  int countCore0 = 0;
  int countCore1 = 0;
  String stringCore0;
  String stringCore1;
#endif


void setup()
{
  #ifdef DEBUG
    Serial.begin(115200); // For communications to PC
    rp2040.idleOtherCore(); // Allow delay to affect both cores, to ensure stable synchronisation from start
    delay(10000);
    rp2040.resumeOtherCore();
  #endif
  
  #ifdef VERBOSE
    stringCore0 += "\n\r*** setup() started!";
  #endif

  pinMode(LED_BUILTIN, OUTPUT); // for heartBeat

  #ifdef VERBOSE
    stringCore0 += "\n\r*** setup() completed!";
  #endif
}

void setup1()
{
  #ifdef VERBOSE
    stringCore1 += "\n\r*** setup1() started!";
  #endif

  #ifdef VERBOSE
    stringCore1 += "\n\r*** setup1() completed!";
  #endif
}

void loop()
{
  #ifdef VERBOSE
    stringCore0 += "\n\rStarting loop()";
    countCore0++;
    stringCore0 += "\n\r   loop() count = " + String(countCore0);
  #endif

  heartBeat();

  #ifdef DEBUG
    printData();
  #endif

  #ifdef VERBOSE
    stringCore0 += "\n\rloop() completed!\n\r";
  #endif
}

void loop1()
{
  #ifdef VERBOSE
    stringCore1 += "\n\rStarting loop1()";
  #endif
  
  countCore1++;
  stringCore1 += "\n\r   loop1() count = " + String(countCore1);

  #ifdef VERBOSE
    stringCore1 += "\n\rloop1() completed!\n\r";
  #endif
}

void heartBeat()
{
  digitalWrite(LED_BUILTIN, heartBeatState);
  if (heartBeatTime < millis())
  {
    heartBeatState = !heartBeatState; // Change state
    heartBeatTime = millis() + 1000; // Update to 1 second from now
  }
}


void printData() // Called from Core0
{
  // Pause the other core (Core 1), copy stringCore1, clear stringCore1, then resume other core (Core 1)
  //rp2040.idleOtherCore();
  String copyOfstringCore1 = stringCore1;
  stringCore1 = "";
  //rp2040.resumeOtherCore();

  Serial.print(stringCore0);
  stringCore0 = "";
  Serial.print(copyOfstringCore1);
  copyOfstringCore1 = "";
}
2

I can not find the Raspberry Pi Pico W in the boards in the Arduino IDE. Are you using the 'earlephilhower' ? Is that without Mbed ?

3

Arduino IDE 2.2.1

Raspberry Pi RP2040 Boards(2.5.2)

--> Raspberry Pi Pico W

4

Can you just say which build environment you use ?

This is the Raspberry Pi Pico by Arduino:
afbeelding

That is a Arduino layer on top of Mbed.
The Raspberry Pi Pico W is not supported.

afbeelding
afbeelding1071×524 47.5 KB

I'm am also using the newest Arduino IDE, version 2.2.1.

5

I'm using Arduino Mbed OS RP2040.

At present, my sketch isn't currently using any wireless functionality (I plan to build that in later, once (if) I get the dual-core operation working properly.

6

So you don't have a board with version 2.5.2 and you have not selected a Raspberry Pi Pico W ? I'm very confused.

7

If each core has one variable only it can write, Core 1 writes a value to the Core 1 variable and Core 0 writes the inverse to its' variable.

But with each having a status word, the status of data ready or not can keep clashes from happening. On a PICO. 32 bits is atomic.

8

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