UART trash value on Thingy91

[Nahan_Trogn]

Hi Devzone,

I use Thingy91. On the nrf9160 side, I run mqtt_simple example; on the nrf52840, I run connectivity_bridge with BLE feature.

When I send "900" via nus service, what I receive on nrf9160 side are:

The reason is because of noise or software config?

Thanks in advance.

Development setup: Ubuntu, ncs v1.5.1, Thingy91.

And this is my additional file to the original example. I also change AT Host to uart1 (to unused it)

Fullscreen my_uart_handler.c Download

#include "my_uart_handler.h"
#include <drivers/uart.h>
#include <zephyr.h>
#include <stdio.h>
#include <string.h>
#include <logging/log.h>
#include "my_led.h"

LOG_MODULE_REGISTER(my_uart, 3);

#define CONFIG_UART_0_NAME      "UART_0"
static led_color color = {.c[0] = 250, .c[1] = 10, .c[2] = 5};
static const struct device *uart_dev;
char my_rx_buffer[100];
static uint8_t i;
bool rcv_flg = false;
bool ctrl_flag = false;
static bool receive_handler(char input)
{

  switch (input)
  {
    case 'I':
      rcv_flg = true;
      return;
      break;
    case 'Q':
      rcv_flg = false;
      break;
    default:
      break;
  }

  if (rcv_flg)
  {
    if ((input >= 48)&&(input <= 57))
    strcat(my_rx_buffer,&input);
    ctrl_flag = true;
    //if (i++ >= 5) rcv_flg = false;
  }
  else
  {
    //LOG_INF("rcv12: %s",log_strdup(my_rx_buffer));
    if (ctrl_flag)
    {
      color.c[0] = my_rx_buffer[0];
      color.c[1] = my_rx_buffer[1];
      color.c[2] = my_rx_buffer[2];
      pwm_out(&color);
      ctrl_flag = false;
    }
    memset(my_rx_buffer,0,100);
  } 

}

static void isr(const struct device *dev, void *user_data)
{
	ARG_UNUSED(user_data); 
        char character;
	uart_irq_update(dev);

	if (!uart_irq_rx_ready(dev)) {
		return;
	}
        LOG_INF("rcv");
        while (uart_fifo_read(dev, &character, 1))
        {
          receive_handler(character);
        }


}


static int my_uart_init(const struct device *arg)
{
  ARG_UNUSED(arg);

  int err;
  uint8_t dummy;

  uart_dev = device_get_binding(CONFIG_UART_0_NAME);
  if (uart_dev == NULL) {
          LOG_ERR("Cannot bind %s\n", CONFIG_UART_0_NAME);
          return -EINVAL;
  }

  uint32_t start_time = k_uptime_get_32();

  /* Wait for the UART line to become valid */
  do {
          err = uart_err_check(uart_dev);
          if (err) {
                  if (k_uptime_get_32() - start_time >
                      500) {
                          LOG_ERR("UART check failed: %d. "
                                  "UART initialization timed out.", err);
                          return -EIO;
                  }

                  LOG_INF("UART check failed: %d. "
                          "Dropping buffer and retrying.", err);

                  while (uart_fifo_read(uart_dev, &dummy, 1)) {
                          /* Do nothing with the data */
                  }
                  k_sleep(K_MSEC(10));
          }
  } while (err);

  uart_irq_callback_set(uart_dev, isr);
  uart_irq_rx_enable(uart_dev);
  return err;

}
SYS_INIT(my_uart_init, APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);

[Carl Richard]

Hello!

Thanks for reaching out. I agree with awneil here that you should make sure you know what's being sent/recived, as it seems like there is a consistenty in the wrong data (i.e. it's not junk, but something else). Could it be that some line breaks are transmitted with the message as well? 

What sample is your application based on?

I will test your code on Monday to see if I can reproduce this. 

Best regards,
Carl Richard

[Nahan_Trogn]

Hi,

I found that the problem came from strcat function. When when I assign each character (read from uart) to my array, the problem disappeared. Currently I don't know how to use strcat so that there is no garbage value.

[awneil]

strcat is a standard C library function - so plenty of documentation on how to use it; eg,

http://www.cplusplus.com/reference/cstring/strcat/

Remember that C strings need a NUL termination - which you won't get when reading direct from a UART ...

Perhaps show what you were doing with strcat ?

[Nahan_Trogn]

I use strcat to add an individual character to a string (array buffer). I can achieve this by assigning each character for each member in the array.

[awneil]

Nahan_Trogn said:

use strcat to add an individual character to a string (array buffer).

Again, strcat is a standard C library function - so plenty of documentation on how to use it; eg,

http://www.cplusplus.com/reference/cstring/strcat/

As you can see, both of its parameters need to be C strings - so you can't just use it to add an individual character without first making that character a string ...