bytes after a 0x00 are not sent

[zeroby0]

For value for BLECharacteristic, bytes after a 0x00 byte are not sent. This is probably because BLECharacteristic uses char for payload and 0x00 is being treated as the '\0' character.

What it means is that custom binary data cannot be sent. For example, 0x00 0xF0 0x00 is received as an empty message.

Here is an example sketch. You can check notifications via Web-Bluetooth at this url https://googlechrome.github.io/samples/web-bluetooth/notifications-async-await.html?service=0xfff0&characteristic=0xfff1.

#include <SPI.h>
#include <BLEPeripheral.h>

char data[3];
char buffer[20];

BLEPeripheral blePeripheral = BLEPeripheral();
BLEService s_primary = BLEService("fff0");
BLECharacteristic c_data = BLECharacteristic("fff1", BLERead | BLEIndicate, 3);

void setup() {
  Serial.begin(115200);

  blePeripheral.setLocalName("Nrf52");
  blePeripheral.setAdvertisedServiceUuid(s_primary.uuid());

  blePeripheral.addAttribute(s_primary);
  blePeripheral.addAttribute(c_data);

  blePeripheral.begin();

  data[0] = 0x00;
  data[1] = 0xF0;
  data[2] = 0x00;
}

void loop() {
  BLECentral central = blePeripheral.central();

  if (central) {
    Serial.print(F("Connected to central: "));
    Serial.println(central.address());

    while (central.connected()) {
        if(c_data.setValue(data)) {
            sprintf(buffer, "data: %02X %02X %02X", data[0], data[1], data[2]);
            Serial.println(buffer);
        }

        delay(1000);
    }

    Serial.print(F("Disconnected from central: "));
    Serial.println(central.address());
  }
}

The same output as Web-Bluetooth is received in Nordic nRF Connect app as well.

Using BLEFixedLengthCharacteristic instead sends wrong data. For example, for 0x00 0xF0 0x00 as payload, I receive 0x32 0x99 0x1B.

Other details

I'm using the nrf51-indicate-fix branch.

My chip is NRF52832, the issue with fixed length is probably not related to the chip, I don't have an NRF51 chip to verify.

I'm using platformIO ide on vscode. Here is my platformio.ini file

[env:nrf52_dk]
platform = nordicnrf52
board = nrf52_dk
framework = arduino
monitor_speed = 115200
debug_tool = jlink
; SoftDevice version
build_flags = -DNRF52_S132
lib_deps =
  https://github.com/sandeepmistry/arduino-BLEPeripheral/archive/nrf51-indicate-fix.zip

With FixedLength size of 20, here is the output I get: 0x32 0x99 0x1b 0xc3 0xfe 0x9f 0xed 0xfc 0x24 0x00 0x00 0x00 0xfc 0xff 0xff 0xff 0x34 0x23 0x00 0x20. This doesn't change even when payload changes.

[atc1441]

Hi, you can make it work by giving a length with the setValue

Here as example:

const unsigned char data[3];

int len = 3;

c_data.setValue(data,len);

[zeroby0]

I see, thanks 😄