HardwareSerial incorrect timing with non standard baudrate

[aster94]

Hardware:

Board: ESP32 Lolin 32 mini
Core Installation/update date: last from package manager (1.0.0?)
IDE name: vscode
Flash Frequency: tried both 40 and 80MHz
Upload Speed: 460800
Computer OS: xubuntu 18.04

Description:

Using a baudrate different form the standard (10400) brings to incorrect timing of the serial communication
I made a few samples with a salea logic analizer (clone) with the above settings:

Correct behaviour from an arduino mega:

mega 10400 o.txt

while esp plays a few jokes

esp 10400 o.txt

same at 80mhz

esp 80 10400 o.txt

same happens if i remove the odd parity bit

esp 10400 n.txt

while at a standard baud rate (115200) all is ok

esp 115200 n.txt

Sketch:

for esp

HardwareSerial ser(2);

void setup()
{
    ser.begin(10400,SERIAL_8O1);
}

void loop()
{
    for (uint8_t n = 1; n < 10; n++)
    {
        ser.write(n);
        delay(10);
    }
    delay(100);
}

for arduino mega

void setup()
{
    Serial2.begin(10400,SERIAL_8O1);
}

void loop()
{
    for (uint8_t n = 1; n < 10; n++)
    {
        Serial2.write(n);
        delay(10);
    }
    delay(100);
}

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[aster94]

i suggest not to close this

[stale]

[STALE_SET] This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

[aster94]

.

[stale]

[STALE_CLR] This issue has been removed from the stale queue. Please ensure activity to keep it openin the future.

[lbernstone]

Please modify and test the following code adapted directly from esp-idf uart example to see if the behavior is coming from the hardware or software.
https://docs.espressif.com/projects/esp-idf/en/v3.2/api-reference/peripherals/uart.html

/* UART Echo Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/uart.h"

/**
 * This is an example which echos any data it receives on UART1 back to the sender,
 * with hardware flow control turned off. It does not use UART driver event queue.
 *
 * - Port: UART1
 * - Receive (Rx) buffer: on
 * - Transmit (Tx) buffer: off
 * - Flow control: off
 * - Event queue: off
 * - Pin assignment: see defines below
 */

#define ECHO_TEST_TXD  (GPIO_NUM_4)
#define ECHO_TEST_RXD  (GPIO_NUM_5)
#define ECHO_TEST_RTS  (UART_PIN_NO_CHANGE)
#define ECHO_TEST_CTS  (UART_PIN_NO_CHANGE)

#define BUF_SIZE (1024)
// Configure a temporary buffer for the incoming data
uint8_t *data = (uint8_t *) malloc(BUF_SIZE);  

void setup() {
    /* Configure parameters of an UART driver,
     * communication pins and install the driver */
    uart_config_t uart_config = {
        .baud_rate = 115200,
        .data_bits = UART_DATA_8_BITS,
        .parity    = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE
    };
    uart_param_config(UART_NUM_1, &uart_config);
    uart_set_pin(UART_NUM_1, ECHO_TEST_TXD, ECHO_TEST_RXD, ECHO_TEST_RTS, ECHO_TEST_CTS);
    uart_driver_install(UART_NUM_1, BUF_SIZE * 2, 0, 0, NULL, 0);
}

void loop() {
        // Read data from the UART
        int len = uart_read_bytes(UART_NUM_1, data, BUF_SIZE, 20 / portTICK_RATE_MS);
        // Write data back to the UART
        uart_write_bytes(UART_NUM_1, (const char *) data, len);
}

[aster94]

@lbernstone thanks for the help, i tried:

HardwareSerial ser(2);

void setup()
{
    ser.begin(10400,SERIAL_8O1);
}

void loop()
{
    for (uint8_t n = 1; n < 10; n++)
    {
        ser.write(n);
        delay(10);
    }
    delay(100);
}

and

#include <Arduino.h>

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/uart.h"

#define ECHO_TEST_TXD (GPIO_NUM_17)
#define ECHO_TEST_RXD (GPIO_NUM_16)
#define ECHO_TEST_RTS (UART_PIN_NO_CHANGE)
#define ECHO_TEST_CTS (UART_PIN_NO_CHANGE)

#define BUF_SIZE 1024

void setup()
{
  uart_config_t uart_config = {
      .baud_rate = 10400,
      .data_bits = UART_DATA_8_BITS,
      .parity = UART_PARITY_DISABLE,
      .stop_bits = UART_STOP_BITS_1,
      .flow_ctrl = UART_HW_FLOWCTRL_DISABLE};
  uart_param_config(UART_NUM_2, &uart_config);
  uart_set_pin(UART_NUM_2, ECHO_TEST_TXD, ECHO_TEST_RXD, ECHO_TEST_RTS, ECHO_TEST_CTS);
  uart_driver_install(UART_NUM_2, BUF_SIZE * 2, 0, 0, NULL, 0);
}

void loop()
{
  const char *data = "test";
  uart_write_bytes(UART_NUM_2, data, 5);
  delay(2);
}

This is the output:
test.zip

To me looks like an hardware problem, any thoughts? may I have modified in a wrong way your example sketch?

[lbernstone]

I can't see anything in your Matrix data, Cypher.
If you are seeing the same result from the uart code as you get from HardwareSerial, then I suggest you open up an issue at the ESP-IDF forum

[stale]

[STALE_SET] This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.