Hammingstream using ESP32 only receiving question marks.

[Klon64]

Hi Benoit,

I'm using the provided "HammingSerial1" Sketch with an ESP32 looping the TX and RX pins for testing, but only receiving "????" as outputs on the serial monitor.
So far, I've tried remapping the UART to other Pins and connecting the ESP32 to an Arduino Nano Every (with level shifter), which resulted in further question marks on the ESP side, despite the Nano working flawlessly.
ESP32 Board: https://www.az-delivery.de/en/products/esp32-developmentboard

Best regards
Felix

[bblanchon]

Hi @Klon64,

Can you double-check that the transmission works correctly without the HammingStream?
Can you share a short repro code?

Best regards,
Benoit

[Klon64]

Hi Benoit,

The transmission without HammingStream works as intented.

#include <StreamUtils.h>

HammingStream<7, 4> eccSerial1(Serial1);

void setup() {
  Serial.begin(115200);
  delay(500);
  while (!Serial)
    continue;

  Serial1.begin(9600);
  delay(500);
  while (!Serial1)
    continue;

  // Discard any remaining data in the input buffer
  while (Serial1.available())
    Serial1.read();
}

void loop() {
  //noecc();
  // Did we receive something?
  if (eccSerial1.available())
    // Print it
    Serial.write(eccSerial1.read());

  // Do we have something to send?
  if (Serial.available())
    // Sent it
    eccSerial1.write(Serial.read());
}

void noecc() {
  // Did we receive something?
  if (Serial1.available())
    // Print it
    Serial.write(Serial1.read());

  // Do we have something to send?
  if (Serial.available())
    // Sent it
    Serial1.write(Serial.read());
}

Best regards,
Felix

[bblanchon]

Hi Felix,

I tried your program on an Arduino Leonardo, and it works perfectly.

However, when I run it on an ESP32, it resets when it executes Serial1.begin(9600);.
I don't have the time to investigate why I can't use Serial1 on my ESP32, and it doesn't seem to be related to your problem anyway.

Best regards,
Benoit

[Klon64]

Hi Benoit,

Serial1 is used for the Flash on some ESP32 boards. I tried the same Code with Serial2 and get the same results.

#include <StreamUtils.h>

HammingStream<7, 4> eccSerial1(Serial2);

void setup() {
  Serial.begin(115200);
  delay(500);
  while (!Serial)
    continue;

  Serial2.begin(9600);
  delay(500);
  while (!Serial2)
    continue;

  // Discard any remaining data in the input buffer
  while (Serial2.available())
    Serial2.read();
}

void loop() {
  //noecc();
  ecc();
}

void noecc() {
  // Did we receive something?
  if (Serial2.available())
    // Print it
    Serial.write(Serial2.read());

  // Do we have something to send?
  if (Serial.available())
    // Sent it
    Serial2.write(Serial.read());
}

void ecc() {
    // Did we receive something?
  if (eccSerial1.available())
    // Print it
    Serial.write(eccSerial1.read());

  // Do we have something to send?
  if (Serial.available())
    // Sent it
    eccSerial1.write(Serial.read());
}

If Serial2 does not work either, you can also remap the pins like this.

Serial2.begin(9600,SERIAL_7N1,18,19);

Best regards,
Felix

[bblanchon]

Hi Felix,

Thank you very much for these instructions!
They helped me reproduce the bug and ultimately fixed the issue: I used a char to store a signed value, but on ESP32, the char type is unsigned.

I'll release a new version once the CI build passes.

Thanks a lot for reporting this bug ❤️

Best regards,
Benoit