Help me with Hardware Serial

[carminelau]

Hi I have an esp32 and I connected a PMS A003 to the serial hardware (IO10, IO9) but it doesn't work, I always get "Sensor read timeout". I used the HardwareSerial.ino sample code

[avaldebe]

Hi @carminelau

On some boards, like the ESP32 MiniKit, those pins are conected to the flash and using them might crash your board.

Other option is that your RX/TX lines are swapped. You need to connect them like this:

• ESP32 TX --> RX PMSA003
• ESP32 RX <-- TX PMSA003

Hope this helps

[carminelau]

My board is ESP32 WROVER-B can you help me ?

[carminelau]

This is my esp32, i used the GPIO 9 and GPIO10 but my esp crash always

[avaldebe]

This is my esp32, i used the GPIO 9 and GPIO10 but my esp crash always

Your problem might be related to this issue:

UART1 defaults to pins 9 and 10 which are used by the onboard flash. Either use UART2 on pins 16 and 17 or define the pins you want to use when starting UART1

Originally posted by @me-no-dev in https://github.com/espressif/arduino-esp32/issues/148#issuecomment-275635651

Is this crash related from the use of this library? Or it always crash when using Serial1? Can you try using Serial2 as in the example?

[carminelau]

Always crash when using Serial1, Serial2 or istanziate with RX and Tx

[carminelau]

I use this code for testing...

#include <PMserial.h>
SerialPM pms(PMSA003, Serial1);  // PMSx003, UART   RX GPIO9 TX GPIO10

void setup() {
  Serial.begin(9600);
  pms.init();                   // config serial port
}

void loop() {
  pms.read();                   // read the PM sensor
  Serial.print(F("PM1.0 "));Serial.print(pms.pm01);Serial.print(F(", "));
  Serial.print(F("PM2.5 "));Serial.print(pms.pm25);Serial.print(F(", "));
  Serial.print(F("PM10 ")) ;Serial.print(pms.pm10);Serial.println(F(" [ug/m3]"));
  delay(10000);                 // wait for 10 seconds
}

can you help me ? i'm really tired.

[avaldebe]

Just to be sure, you have tied with Serial2, l like in the following?

#include <PMserial.h>
SerialPM pms(PMSA003, Serial2);  // PMSx003, UART   RX GPI16 TX GPIO17
...

[carminelau]

No, I honestly don't know how to enable Serial2.

[avaldebe]

just change the line as I showed on my previous message and connect the sensor the GPIO 16 and 17

[carminelau]

if I want to use the pins I said GPIO9 and GPIO10 how should I do?

[avaldebe]

if I want to use the pins I said GPIO9 and GPIO10 how should I do?

You first need to check that the pins are usable. Maybe you can first try with a simple echo sketch, like this one:

void setup() {
  Serial.begin(9600);
  Serial1.begin(9600);

  Serial.println("hello from Serial");
}

void loop() {
  if Serial.available() {
    Serial1.write(Serial.read());
  } 
  if Serial1.available() {
    Serial.write(Serial1.read());
  } 
}

and connect GPIO9 and GPIO10 with a jumper wire. You should get the message "hello from Serial" on the serial monitor (or whatever the Arduino IDE calls it).

[me-no-dev]

To use different pins for Serial1, you should initialize it as below:

Serial1.begin(9600, SERIAL_8N1, rxPin, txPin);

[heX16]

I use this code for testing...

If you linking Serial object directly, you must make manual configure this object.

SerialPM pms(PMSA003, Serial1);

void setup() {
  Serial1.begin(9600, SERIAL_8N1, _RX_, _TX_); // <- manual configure
  pms.init();

See more: https://github.com/avaldebe/PMserial/tree/master/examples/SoftwareSerial#esp32-minikit

[avaldebe]

@carminelau

did you get the sensor working on Serial1?

[carminelau]

No, the serial1 it is not usable in my esp32

[avaldebe]

No, the serial1 it is not usable in my esp32

Did you try to use different pins, as @me-no-dev and @heX16 suggested?