We have found what appears an easily reproducible bug in nrf_serial_read.
Reproduce as follows:
* PCA10040
* SDK 15.3
* SES
* Example project peripheral serial
* Change to Flow control disabled
* Change the timeout parameter on nrf_serial_read to 0 (is 1000)
Now when you do the echo loop occasionally you will see random characters.
I cant see any reason that a zero timeout shouldnt work..?
PS: You can close the previous ticket: "Stuck TX interrupt with nrf_serial_write" - it was a bug in receiving terminal.
Hi,
occasionally you will see random characters
Can you give an example?
Do you send anything to the board from another device, or do you connect TX to RX?
Best regards,
Jørgen
No, it is complete reproducible just with the standard peripheral/serial project in the SDK. As you know that simply does an echo back of the characters you type in a terminal connected to the usb port of the PCA10040.
So if you try the example project, you will see that it works as it comes in the SDK, but by simply making the 2 changes I list above (remove flow control and set timeout to 0), random characters will occur as you type and echo at slow speed.
It cant be overrun condition, since it is just slow typing at 115200 and under that condition flow control should not be needed.
Anything further I can provide to help u reproduce this bug?
Hi,
Sorry for the long delay before my reply on this issue.
I did some testing today, and I think I found what is causing the issue you are seeing.
When you pass 0 as an argument to the timeout_ms parameter, the transfer will operate in non-blocking mode. Since you have no delay, the same buffer will be passed to the library's RX queue multiple times, and it is potentially overwritten by a transfer. You should make sure that the previous transfer is completed, before starting a new transfer with the same buffer. This can be done by implementing the event handler, and use a flag to wait for the completion. I'm not able to reproduce the issue with the following code:
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*/
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
#include "nrf.h"
#include "nrf_drv_clock.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_drv_power.h"
#include "nrf_serial.h"
#include "app_timer.h"
#include "app_error.h"
#include "app_util.h"
#include "boards.h"
/** @file
* @defgroup nrf_serial_example main.c
* @{
* @ingroup nrf_serial_example
* @brief Example of @ref nrf_serial usage. Simple loopback.
*
*/
uint8_t rx_done = false;
#define OP_QUEUES_SIZE 3
#define APP_TIMER_PRESCALER NRF_SERIAL_APP_TIMER_PRESCALER
NRF_SERIAL_UART_DEF(serial_uart, 0);
static void sleep_handler(void)
{
__WFE();
__SEV();
__WFE();
}
static void event_handler(struct nrf_serial_s const *p_serial, nrf_serial_event_t event)
{
switch(event)
{
case NRF_SERIAL_EVENT_RX_DATA:
{
rx_done = true;
}
break;
}
}
NRF_SERIAL_DRV_UART_CONFIG_DEF(m_uart0_drv_config,
RX_PIN_NUMBER, TX_PIN_NUMBER,
RTS_PIN_NUMBER, CTS_PIN_NUMBER,
NRF_UART_HWFC_DISABLED, NRF_UART_PARITY_EXCLUDED,
NRF_UART_BAUDRATE_115200,
UART_DEFAULT_CONFIG_IRQ_PRIORITY);
#define SERIAL_FIFO_TX_SIZE 32
#define SERIAL_FIFO_RX_SIZE 32
NRF_SERIAL_QUEUES_DEF(serial_queues, SERIAL_FIFO_TX_SIZE, SERIAL_FIFO_RX_SIZE);
#define SERIAL_BUFF_TX_SIZE 1
#define SERIAL_BUFF_RX_SIZE 1
NRF_SERIAL_BUFFERS_DEF(serial_buffs, SERIAL_BUFF_TX_SIZE, SERIAL_BUFF_RX_SIZE);
NRF_SERIAL_CONFIG_DEF(serial_config, NRF_SERIAL_MODE_IRQ,
&serial_queues, &serial_buffs, event_handler, sleep_handler);
int main(void)
{
ret_code_t ret;
ret = nrf_drv_clock_init();
APP_ERROR_CHECK(ret);
ret = nrf_drv_power_init(NULL);
APP_ERROR_CHECK(ret);
nrf_drv_clock_lfclk_request(NULL);
ret = app_timer_init();
APP_ERROR_CHECK(ret);
// Initialize LEDs and buttons.
bsp_board_init(BSP_INIT_LEDS | BSP_INIT_BUTTONS);
ret = nrf_serial_init(&serial_uart, &m_uart0_drv_config, &serial_config);
APP_ERROR_CHECK(ret);
static char tx_message[] = "Hello nrf_serial!\n\r";
ret = nrf_serial_write(&serial_uart,
tx_message,
strlen(tx_message),
NULL,
NRF_SERIAL_MAX_TIMEOUT);
APP_ERROR_CHECK(ret);
while (true)
{
static char c;
while(rx_done == false);
rx_done = false;
ret = nrf_serial_read(&serial_uart, &c, sizeof(c), NULL, 0);
if (ret != NRF_SUCCESS)
{
continue;
}
(void)nrf_serial_write(&serial_uart, &c, sizeof(c), NULL, 0);
(void)nrf_serial_flush(&serial_uart, 0);
}
}
/** @} */
Best regards,
Jørgen