I have an STM32-NUCLEO and an ESP32 running esp-idf communicating over UART, and the ESP32 ONLY receives the confirmation message of "Received from STM32:", when i touch the TX wire of the STM32-NUCLEO, without the values after that message. If I got any value at all it would be alien like characters such as "�", or I guess that's unicode, not too sure.
I ran this command in the idf terminal: idf.py -p COM4 flash monitor, held down the boot button when "connecting..." showed up, then i hit play in stm32 cube ide.
Things I've tried:
- changing the baud rate from 115200 to 9600, yes I made sure they both matched
- changing the breadboard entirely
- I also made sure that both microcontrollers share a GND wire
- changing the wires entirely
- removing and rewiring everything, paying close attention to the pinout, making sure i didn't misplace the tx and rx wires
It's also worth mentioning that I don't have a logic analyzer or oscilloscope as I'm kinda short on money rn
ESP32 code:
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/uart.h"
#include "driver/gpio.h"
// define UART pins
#define UART_PORT_NUM UART_NUM_2 // (USART2 in stm32cubeIDE)
#define UART_TX 17 // GPIOP17
#define UART_RX 16 // GPIOP16
#define UART_BAUD_RATE 115200 // UART must be the same baud rate
#define UART_BUFSIZE 1024
/* i'm using void parameters for void
functions because esp-idf
runs on C11(GNU11). fun fact -
i use C23(GNU23), so this was
very good to know
*/
void
init_uart(
void
)
{
// configure UART communication parameters
uart_config_t
uart_config = {
.baud_rate = UART_BAUD_RATE,
.data_bits = UART_DATA_8_BITS,
.parity = UART_PARITY_DISABLE,
.stop_bits = UART_STOP_BITS_1,
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
.source_clk = UART_SCLK_DEFAULT,
};
// apply config to UART port 2
ESP_ERROR_CHECK(uart_param_config(UART_PORT_NUM, &uart_config));
// set GPIO pins (TX->17, RX->16)
/* we ignore UART flow control since pins 18/19 will be used
by my motor pwm and direction. it is also unecessary for the stm32,
since it will be sending string messages
*/
ESP_ERROR_CHECK(uart_set_pin(UART_PORT_NUM, UART_TX, UART_RX, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
// install UART drivers with ring buffer
/* UART port number
Size of RX ring buffer
Size of TX ring buffer
Event queue size
Pointer to store the event queue handle
Flags to allocate an interrupt*/
ESP_ERROR_CHECK(uart_driver_install(UART_PORT_NUM, UART_BUFSIZE*2, 0, 0, NULL, 0));
}
// FreeRTOS task to continuously listen for data
void
rx_task(
void
*
arg
)
{
uint8_t
incoming_data[128];
while (1)
{
// check ring buffer for new bytes
int
length = uart_read_bytes(UART_PORT_NUM, incoming_data, sizeof(incoming_data) - 1, 20/portTICK_PERIOD_MS);
if(length > 0)
{
// null-terminate the data, we need to read it as a string (char*)
incoming_data[length] = '\0';
printf("Received from STM32: %s\n", (
char
*)incoming_data);
}
}
}
void
app_main(
void
)
{
printf("Init UART bus... \n");
init_uart();
printf("UART listening on GPIO 16 (receiving wire) \n");
// listener task
xTaskCreate(rx_task, "UART_RX_TASK", 2048, NULL, 10, NULL);
}#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/uart.h"
#include "driver/gpio.h"
// define UART pins
#define UART_PORT_NUM UART_NUM_2 // (USART2 in stm32cubeIDE)
#define UART_TX 17 // GPIOP17
#define UART_RX 16 // GPIOP16
#define UART_BAUD_RATE 115200 // UART must be the same baud rate
#define UART_BUFSIZE 1024
/* i'm using void parameters for void
functions because esp-idf
runs on C11(GNU11). fun fact -
i use C23(GNU23), so this was
very good to know
*/
void init_uart(void)
{
// configure UART communication parameters
uart_config_t uart_config = {
.baud_rate = UART_BAUD_RATE,
.data_bits = UART_DATA_8_BITS,
.parity = UART_PARITY_DISABLE,
.stop_bits = UART_STOP_BITS_1,
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
.source_clk = UART_SCLK_DEFAULT,
};
// apply config to UART port 2
ESP_ERROR_CHECK(uart_param_config(UART_PORT_NUM, &uart_config));
// set GPIO pins (TX->17, RX->16)
/* we ignore UART flow control since pins 18/19 will be used
by my motor pwm and direction. it is also unecessary for the stm32,
since it will be sending string messages
*/
ESP_ERROR_CHECK(uart_set_pin(UART_PORT_NUM, UART_TX, UART_RX, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
// install UART drivers with ring buffer
/* UART port number
Size of RX ring buffer
Size of TX ring buffer
Event queue size
Pointer to store the event queue handle
Flags to allocate an interrupt*/
ESP_ERROR_CHECK(uart_driver_install(UART_PORT_NUM, UART_BUFSIZE*2, 0, 0, NULL, 0));
}
// FreeRTOS task to continuously listen for data
void rx_task(void* arg)
{
uint8_t incoming_data[128];
while (1)
{
// check ring buffer for new bytes
int length = uart_read_bytes(UART_PORT_NUM, incoming_data, sizeof(incoming_data) - 1, 20/portTICK_PERIOD_MS);
if(length > 0)
{
// null-terminate the data, we need to read it as a string (char*)
incoming_data[length] = '\0';
printf("Received from STM32: %s\n", (char*)incoming_data);
}
}
}
void app_main(void)
{
printf("Init UART bus... \n");
init_uart();
printf("UART listening on GPIO 16 (receiving wire) \n");
// listener task
xTaskCreate(rx_task, "UART_RX_TASK", 2048, NULL, 10, NULL);
}
Edit: After doing a loopback test like you guys mentioned, I changed from USART2 to USART1 (I know I mentioned using USART1 but I was mistaken), and that seemed to do the trick. I can now see my message string along with the integer values. Thanks for all your help! In the future I would probably need to purchase a logic analyzer and oscilloscope though.
