Hi.
I am developing a custom board using the NRF52840. The mcu needs to connect to a modem and a gnss module. Both modules will communicate with the mcu over UART
I'm using the app_uart API, and it's not quite clear how to use this API with 2 instances (and when I say 2 "instances", I mean 2 physical UART interfaces). Is that even posible?
Thanks.
Tim
APP_UART uses hardcoded instance in app_uart.c and app_uart_fifo.c in the below line.
static nrf_drv_uart_t app_uart_inst = NRF_DRV_UART_INSTANCE(APP_UART_DRIVER_INSTANCE);
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#include "sdk_common.h"
#if NRF_MODULE_ENABLED(APP_UART)
#include "app_uart.h"
#include "nrf_drv_uart.h"
#include "nrf_assert.h"
static uint8_t tx_buffer[1];
static uint8_t rx_buffer[1];
static volatile bool rx_done;
static app_uart_event_handler_t m_event_handler; /**< Event handler function. */
static nrf_drv_uart_t app_uart_inst = NRF_DRV_UART_INSTANCE(APP_UART_DRIVER_INSTANCE_1);
static void uart_event_handler(nrf_drv_uart_event_t * p_event, void* p_context)
{
if (p_event->type == NRF_DRV_UART_EVT_RX_DONE)
{
// Received bytes counter has to be checked, because there could be event from RXTO interrupt
if (p_event->data.rxtx.bytes)
{
app_uart_evt_t app_uart_event;
app_uart_event.evt_type = APP_UART_DATA;
app_uart_event.data.value = p_event->data.rxtx.p_data[0];
rx_done = true;
m_event_handler(&app_uart_event);
}
(void)nrf_drv_uart_rx(&app_uart_inst, rx_buffer, 1);
}
else if (p_event->type == NRF_DRV_UART_EVT_ERROR)
{
app_uart_evt_t app_uart_event;
app_uart_event.evt_type = APP_UART_COMMUNICATION_ERROR;
app_uart_event.data.error_communication = p_event->data.error.error_mask;
(void)nrf_drv_uart_rx(&app_uart_inst, rx_buffer, 1);
m_event_handler(&app_uart_event);
}
else if (p_event->type == NRF_DRV_UART_EVT_TX_DONE)
{
// Last byte from FIFO transmitted, notify the application.
// Notify that new data is available if this was first byte put in the buffer.
app_uart_evt_t app_uart_event;
app_uart_event.evt_type = APP_UART_TX_EMPTY;
m_event_handler(&app_uart_event);
}
}
uint32_t app_uart1_init(const app_uart_comm_params_t * p_comm_params,
app_uart_buffers_t * p_buffers,
app_uart_event_handler_t event_handler,
app_irq_priority_t irq_priority)
{
nrf_drv_uart_config_t config = NRF_DRV_UART_DEFAULT_CONFIG;
config.baudrate = (nrf_uart_baudrate_t)p_comm_params->baud_rate;
config.hwfc = (p_comm_params->flow_control == APP_UART_FLOW_CONTROL_DISABLED) ?
NRF_UART_HWFC_DISABLED : NRF_UART_HWFC_ENABLED;
config.interrupt_priority = irq_priority;
config.parity = p_comm_params->use_parity ? NRF_UART_PARITY_INCLUDED : NRF_UART_PARITY_EXCLUDED;
config.pselcts = p_comm_params->cts_pin_no;
config.pselrts = p_comm_params->rts_pin_no;
config.pselrxd = p_comm_params->rx_pin_no;
config.pseltxd = p_comm_params->tx_pin_no;
m_event_handler = event_handler;
rx_done = false;
uint32_t err_code = nrf_drv_uart_init(&app_uart_inst, &config, uart_event_handler);
VERIFY_SUCCESS(err_code);
// Turn on receiver if RX pin is connected
if (p_comm_params->rx_pin_no != UART_PIN_DISCONNECTED)
{
return nrf_drv_uart_rx(&app_uart_inst, rx_buffer,1);
}
else
{
return NRF_SUCCESS;
}
}
uint32_t app_uart1_get(uint8_t * p_byte)
{
ASSERT(p_byte);
uint32_t err_code = NRF_SUCCESS;
if (rx_done)
{
*p_byte = rx_buffer[0];
rx_done = false;
}
else
{
err_code = NRF_ERROR_NOT_FOUND;
}
return err_code;
}
uint32_t app_uart1_put(uint8_t byte)
{
tx_buffer[0] = byte;
ret_code_t ret = nrf_drv_uart_tx(&app_uart_inst, tx_buffer, 1);
if (NRF_ERROR_BUSY == ret)
{
return NRF_ERROR_NO_MEM;
}
else if (ret != NRF_SUCCESS)
{
return NRF_ERROR_INTERNAL;
}
else
{
return NRF_SUCCESS;
}
}
uint32_t app_uart1_flush(void)
{
return NRF_SUCCESS;
}
uint32_t app_uart1_close(void)
{
nrf_drv_uart_uninit(&app_uart_inst);
return NRF_SUCCESS;
}
#endif //NRF_MODULE_ENABLED(APP_UART)
Where I have changed the API in app_uart1.c to have app_uart1_init etc.
I also have app_uart_inst in app_uart1.c to use APP_UART_DRIVER_INSTANCE_1 (instead of APP_UART_DRIVER_INSTANCE) which you should add in your sdk_config.h file to use the second instance of the uart in app_uart1.c.
And yes if you want app_uart to be used for two instances it is NOT possible without editing the libraries files.
Second way is to use app_uart for one instance and nrf_drv_uart directly for the second instance.