I'm trying to communicate between two devices (nrf52840 and teensy 3.6) over RS485, but I'm having some issues using the UART library in the SDK. I'm trying to create an interrupt-based response to a packet received over the 485 line, so I've taken the example found under Nordic\examples\peripheral\serial\ and created my own event handler to respond to RX events.
#define OP_QUEUES_SIZE 3
#define APP_TIMER_PRESCALER NRF_SERIAL_APP_TIMER_PRESCALER
#define RS485_EN ARDUINO_2_PIN
#define RS485_TX ARDUINO_1_PIN
#define RS485_RX ARDUINO_0_PIN
static void rs485_evt_handler(nrf_serial_t const * p_serial,
nrf_serial_event_t event)
{
uint32_t ret = 0;
uint8_t rxbyte;
switch(event)
{
case NRF_SERIAL_EVENT_RX_DATA:
{
printf("RX event!\n");
break;
}
case NRF_SERIAL_EVENT_TX_DONE:
{
break;
}
default:
{
printf("UART EVENT - %#010x\n", nrf_drv_uart_errorsrc_get(&p_serial->instance));
break;
}
}
}
static void sleep_handler(void)
{
__WFE();
__SEV();
__WFE();
}
NRF_SERIAL_DRV_UART_CONFIG_DEF(m_uart0_drv_config,
RS485_RX, RS485_TX,
RTS_PIN_NUMBER, CTS_PIN_NUMBER,
NRF_UART_HWFC_DISABLED, NRF_UART_PARITY_EXCLUDED,
NRF_UART_BAUDRATE_9600,
UART_DEFAULT_CONFIG_IRQ_PRIORITY);
#define SERIAL_FIFO_TX_SIZE 32
#define SERIAL_FIFO_RX_SIZE 255
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, rs485_evt_handler, sleep_handler);
NRF_SERIAL_UART_DEF(serial_uart, 0);
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);
nrf_gpio_cfg_output(RS485_EN);
nrf_gpio_pin_clear(RS485_EN);
// 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);
printf("UART ERROR OVERRUN - %#10x\n", NRF_UART_ERROR_OVERRUN_MASK);
printf("UART ERROR BREAK - %#10x\n", NRF_UART_ERROR_BREAK_MASK);
printf("UART ERROR FRAMING - %#10x\n", NRF_UART_ERROR_FRAMING_MASK);
printf("UART ERROR PARITY - %#10x\n", NRF_UART_ERROR_PARITY_MASK);
while (true)
{
// char c;
// ret = nrf_serial_read(&serial_uart, &c, sizeof(c), NULL, 1000);
// if (ret != NRF_SUCCESS)
// {
// continue;
// }
// (void)nrf_serial_write(&serial_uart, &c, sizeof(c), NULL, 0);
// (void)nrf_serial_flush(&serial_uart, 0);
bsp_board_led_invert(0);
nrf_delay_ms(1000);
printf("UART Ready? %d\n", nrf_drv_uart_rx_ready(&serial_uart.instance));
}
}
/** @} */
I'm toggling an activity LED and I've added some prints and comments just for debugging. I've defined SERIAL_BUFF_RX_SIZE to 1, so that the event should fire on every byte received and I made sure to pass my custom event handler to NRF_SERIAL_CONFIG_DEF. Baud rate is set to 9600 and the UART is in IRQ mode.
The problem is that the NRF_SERIAL_EVENT_RX_DATA only fires once, and then the UART appears to lock up and the event doesn't fire again unless I restart the device. I've searched through the UART source files to see why this might be happening, but I can't find anything. My guess is that the RX buffer is overflowing/overrunning, but to be honest the documentation on this module is quite light so I thought I'd post on here to see if anyone could help.
Thanks!
