HardwareSerial esp32-Wrover-kit Uart2

[francescot92]

hi,
I try to use UART2 of the esp32-Wrover-E with Arduino IDE. i know that the UART0 (pin 3 RX pin 1 TX) is for programing UART1(pin 9 RX pin 10 TX) for flash and UART2 (pin 16 RX and pin 17 TX) is free, but in this case these pins (16 and 17) are used to PSRAM.

From datasheet any pins can be used for the UART throuth the library HardwareSerial.h but it seem not work.

i try to communicate two micro throuth UART. i show you the sketch:

this a part of HardwareSerial.cpp:

void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, int8_t txPin, bool invert, unsigned long timeout_ms)
{
if(0 > _uart_nr || _uart_nr > 2) {
log_e("Serial number is invalid, please use 0, 1 or 2");
return;
}
if(_uart) {
end();
}
if(_uart_nr == 0 && rxPin < 0 && txPin < 0) {
rxPin = 3;
txPin = 1;
}
if(_uart_nr == 1 && rxPin < 0 && txPin < 0) {
rxPin = RX1; //RX1
txPin = TX1; //TX1
}
if(_uart_nr == 2 && rxPin < 0 && txPin < 0) {
rxPin = 33; // pin used to UART2
txPin = 32;
}

my sketch:
#include <HardwareSerial.h>

HardwareSerial myUart(2);

String messaggio = "NULL";
char terminatore = '\r';

void setup()
{
// Setup Serial connection:
Serial.begin(115200);
myUart.begin(115200);
delay(1000);
}

void loop
{
if(myUart.available()>0)
{
Serial.print("available:ok\n");
messaggio = Serial2.readStringUntil(terminatore);
}
......

I don’t get anything.
Can you help me??

[lbernstone]

You can assign uart devices to any I/O pins you prefer.

gps_rx=21;
gps_tx=22;
Serial1.begin(9600, SERIAL_8N1, gps_rx, gps_tx);

The external device tx pin is going to be the rx pin on the mcu (and vice versa).

[francescot92]

i use the 115200 bound rate.
i know but i don't get anything. why?? is there anything wrong??

[francescot92]

I get characters different from what I expect why?

[chegewara]

Few things:

• UART1 is not used for flash,
• you dong have to create new HardwareSerial object, there are 3 already in arduino( Serial, Serial1, Serial2),
• your code:

void loop
{
if(myUart.available()>0)   <--------myUart
{
Serial.print("available:ok\n");
messaggio = Serial2.readStringUntil(terminatore); <---------Serial2
}

• i dont know what kind gps do you have, but most usually is using baudrate 9600, so worth to try

[francescot92]

i don't use gps, i'm sorry the mistake. it is only copy trouble.
now it work but I get characters different from what I expect why?
i expect for example: Hello get random characters

i show it in serial port:

17:27:15.657 -> }Ս⸮

[chegewara]

It looks like bitrate does not match. You can try to set it to 0 in begin.

[francescot92]

i have tried it but change the result:

17:45:57.645 -> ⸮

[francescot92]

I noticed that those characters I received with the mass disconnected while, with the mass connected.

[francescot92]

mass = GND

[chegewara]

Yes, it is important to connect GND between 2 devices.

[francescot92]

Yes i know but with the gnd connetted between two device i don’t get anything. Has rx pins needed the pull up?? Mybe that is the reason...

[chegewara]

Time to use scope, logic analyzer and maybe try to swap pins, with the same code.

Been looking through the docs of the WROVER E module, but haven't found the definition of UART1 and UART2 interfaces.. Can someone inform me if they're still available in the module? We are familiar with the HardwareSerial definitions, but in all docs of othr modules, we found the definition in one or another pin. In this one, haven't found them.

We've been using WROVER B, but are looking to upgrade to the newest version.

[chegewara]

WROVER E is just new revison, nothing changed with UARTs.

@chegewara Thanks for the info. Yet, is not that clear for me. So basically the WROVER-E module has the same 3 UART pattern on the pinout, is just not explicitly said in the docs?

Thanks in advance!