Seeed XIAO nrF52840 Sense break Serial (not recognized)

[JpEncausse]

Hello,
I can't get serial data on PlatformIO with Seeed XIAO nrF52840 Sense. The problems seems to comes from the way PlatformIO upload the firmware. It works on ArduinoIDE

Here is my PlatformIO configuration :

[env:seeed_xiao_nrf52840_sense]
platform = https://github.com/Seeed-Studio/platform-seeedboards.git
board = seeed-xiao-afruitnrf52-nrf52840-sense
framework = arduino
build_flags = 
	-w
	-DBOARD_HAS_PSRAM
	-DARDUINO_USB_CDC_ON_BOOT=1 ; Using Zadig to reinstall Driver
	-DCORE_DEBUG_LEVEL=1

And a very simple code :

#include <Arduino.h>
#include <Adafruit_TinyUSB.h>

void setup() {
  Serial.begin(115200);
  while (!Serial);  // Attendre la connexion série
  Serial.println("USB CDC actif");
}

void loop() {
  Serial.println("Ping");
  delay(1000);
}

✅ Using latest version of Arduino IDE it works and serial communication display th Ping. Using Zadig I see a TinyUSB device. Perfect !

❌Using PlatformIO the code is correctly pushed, installed, and run BUT the serial communication is broken, VSCode do not see board/port and Zadig see 2 nRF device (Interface 0 and 2)

I assume PlatformIO is doing something Wrong but ChatGPT loop with wrong advices ... The board and setup seems ok. Any ideas ?

[JpEncausse]

Question/Issue posted on PlatfomrIO community :
https://community.platformio.org/t/seeed-xiao-nrf52840-sense-break-serial-not-recognized/47089

[ackPeng]

The content in the post seems to show that the problem has been solved. Do you have any other questions?

[JpEncausse]

Yes and No the problem is not completly solved.

The correct PlatformIO configuration file

[platformio]
[env:seeed-xiao-afruitnrf52-nrf52840-sense]
platform = Seeed Studio
board = seeed-xiao-afruitnrf52-nrf52840-sense
extra_scripts = pre:fix_link.py

framework = arduino
monitor_speed = 115200

build_unflags =  
build_flags = 
  -Wl,-u,_printf_float
  -Wl,-wrap=realloc

lib_archive = no

Why ? Because

• lib_archive = no is mandatory to fix the CDC Boot issue
• pre:fix_link.py is mandatory for bluefruit libary to compile
• -Wl,-wrap=realloc is mandatory to use String

The pre:fix_link.py content :

Import("env")
from os.path import join

platform = env.PioPlatform()
FRAMEWORK_DIR = platform.get_package_dir("framework-arduinoadafruitnrf52")
env.Append(
    LIBPATH=[join(FRAMEWORK_DIR, "libraries", "Adafruit_nRFCrypto", "src", "cortex-m4", "fpv4-sp-d16-hard")]
)

Bluetooth and BlueFruit

I chose Seeed board because of nrf52840 that can handle 20 BLE devices. But it seems the board is not fully compatible.

1. It requires the correct configuration + hack of Bluefruit
2. The access to the Service or Characteristics is broken

Here is a StackOverflow that describe the problem
https://stackoverflow.com/questions/79584991/bluefruit-no-arduino-access-to-service-or-characteristic-of-nrf52840-devices

In a nutshell the board and/or the library do not read correctly the device data. Advertising is OK but not connecting.

[github-actions]

This issue is stale because it has been open 14 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[ThePradox]

I can confirm that this is still a problem! And a very confusing one, especially if you come from the wiki (https://wiki.seeedstudio.com/xiao_nrf52840_with_platform_io/).
Without lib_archive = no in platformio.ini serial will not work! The nrf52840 will not be visible as a COM port, it's not possible to upload a sketch without double-pressing in bootloader mode, and while (!Serial); will never complete.

While lib_archive = no works, the previous board definition from the wiki (https://github.com/maxgerhardt/platform-nordicnrf52) also works fine.

[ackPeng]

This seems to be a compatibility issue with the library. We will study some solutions to solve it.

[JpEncausse]

Very curious if ther eis some workaround to connect to Bluefruit
https://stackoverflow.com/questions/79584991/bluefruit-no-arduino-access-to-service-or-characteristic-of-nrf52840-devices

[github-actions]

This issue is stale because it has been open 14 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[ackPeng]

In the original compilation rules, I compiled the Adafruit_TinyUSB_Arduino library into the firmware by default to solve the problem of manually #include <Adafruit_TinyUSB.h>, but this caused the serial port to no longer appear after burning the firmware; I solved this problem by removing this library

[ackPeng]

I solved the problem of manually adding pre:fix_link.py by adding BlueFruit to the include list. Now I can compile without pre:fix_link.py. I used a simple demo to verify the blue function, and the data was released normally:

#include <bluefruit.h>

BLEUart bleuart; // uart over ble

// Define hardware: LED and Button pins and states
const int LED_PIN = LED_BUILTIN;
#define LED_OFF LOW
#define LED_ON HIGH


#define BUTTON_ACTIVE LOW
int lastButtonState = -1;

void setup() {
  // Initialize hardware:
  Serial.begin(9600); // Serial is the USB serial port
  pinMode(LED_PIN, OUTPUT); // Turn on-board blue LED off
  digitalWrite(LED_PIN, LED_OFF);

  // Uncomment the code below to disable sharing
  // the connection LED on pin 7.
  //Bluefruit.autoConnLed(false);

  // Initialize Bluetooth:
  Bluefruit.begin();
  // Set max power. Accepted values are: -40, -30, -20, -16, -12, -8, -4, 0, 4
  Bluefruit.setTxPower(4);
  Bluefruit.setName("SparkFun_nRF52840");
  bleuart.begin();

  // Start advertising device and bleuart services
  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
  Bluefruit.Advertising.addTxPower();
  Bluefruit.Advertising.addService(bleuart);
  Bluefruit.ScanResponse.addName();
  
  Bluefruit.Advertising.restartOnDisconnect(true);
  // Set advertising interval (in unit of 0.625ms):
  Bluefruit.Advertising.setInterval(32, 244);
  // number of seconds in fast mode:
  Bluefruit.Advertising.setFastTimeout(30);
  Bluefruit.Advertising.start(0);  
}

void loop() {
  // If data has come in via BLE:
  if (bleuart.available()) {
    uint8_t c;
    // use bleuart.read() to read a character sent over BLE
    c = (uint8_t) bleuart.read();
    // Print out the character for debug purposes:
    Serial.write(c);

    // If the character is one of our expected values,
    // do something:
    switch (c) {
      // 0 number or character, turn the LED off:
      case 0:
      case '0':
        digitalWrite(LED_PIN, LED_OFF);
        break;
      // 1 number or character, turn the LED on:
      case 1:
      case '1':
        digitalWrite(LED_PIN, LED_ON);
        break;
      default:
        break;
    }
  }

  // If our button state has changed:
  int buttonState = !lastButtonState;
  if (buttonState != lastButtonState) {
    lastButtonState = buttonState;
    // Write the new button state to the bleuart TX char
    bleuart.write(!buttonState);
  }
}