UART skipping characters?

[isurki]

Dear Community;

I am trying to read serial data sent by a PMS 5003 in hexadecimal. If I connect the PMS 5003 to a conventional serial device (Raspberry) this is what I read:

42 4d 00 1c 00 07 00 0a 00 0a 00 07 00 0a 00 0a 04 38 01 59 00 30 00 00 00 00 00 00 97 00 02 3e

However, using nRF 9160 DK I read this:

42 4d 00 1c 00 07 00 0a

This is my code. I would like to find out what's wrong.

/*

* Copyright (c) 2012-2014 Wind River Systems, Inc.

*

* SPDX-License-Identifier: Apache-2.0

*/

#include <zephyr.h>
#include <misc/printk.h>
#include <uart.h>
#include <nrf9160.h>

unsigned char uart_buf[1024];

void uart_cb(struct device *x)
{
    static int counter = 0;
	uart_irq_update(x);  //Start processing interrupts in ISR
	int data_length = 0;

	if (uart_irq_rx_ready(x)) {  //Check if UART RX buffer has a received char
		data_length = uart_fifo_read(x, uart_buf, 1024);  //Read data from FIFO
		//printk("bytes: %i", data_length);
		//printk("rx Ready!\n");
		uart_buf[data_length] = 0;
	}
    
    printf("PMS5003 hexadecimal data: %02X\n", (unsigned char) uart_buf[0]);
    counter++;

}

void main(void)
{
	printk("Starting...\n");
	struct device *uart = device_get_binding("UART_0"); //Conecting
	uart_irq_callback_set(uart, uart_cb);  //Set the IRQ callback function pointer
	uart_irq_rx_enable(uart);  //Enable RX interrupt

	printk("UART loopback start!\n");
	while (1) {
		k_cpu_idle(); //Make the CPU idle (useless)
	}
}

Thanks in advance,

Ander.

[Heidi]

Hi! Sorry about the wait. 

Have you tried increasing the buffer size (uart_buf)?

Best regards,

Heidi

[isurki]

Hi Heidi,

I have tried with 1024, 2048, 4096 buff size and I am getting the same results.

Thanks for your answer!

Regards.

[Heidi]

Okay. Could you please attach your prj.conf file? 

[isurki]

yes:

CONFIG_SERIAL=y
CONFIG_TRUSTED_EXECUTION_NONSECURE=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_MAIN_STACK_SIZE=8192
CONFIG_HEAP_MEM_POOL_SIZE=4096

[Heidi]

It looks like you might be blocking yourself, re this line:

printf("PMS5003 hexadecimal data: %02X\n", (unsigned char) uart_buf[0]);

Perhaps try this line instead for printing the received information:

printk("%s", uart_buf);

 

[isurki]

Hi;

I have tried your suggestion and I am reading "BM?z??" from UART.  Letter "B" is 42 interpreted as ASCII, "M" is 4d... but some characters are left.

According to the datasheet, and proven on the Raspberry, I should read  32 bytes of data.

Thanks for your answer.

Regards.

[Heidi]

Okay, thank you for trying. 

I'm pretty sure it's reading out the data faster than it is sent. So try reading out the information byte for byte instead of 1024 at once, and then storing that in a buffer to read out after? 

As long as data_length comes back non-zero:

-Read out one byte
-Store in buffer[count]
-Count++

Then read out buffer after.

[isurki]

Hi Heidi,

I managed to read all 32 bytes using as reference "test_uart_fifo.c" example provided under /zephyr/tests/drivers/uart/uart_basic_api/src/

Regards,

Ander.