4.16. UART¶

4.16.2.1. Driver Configuration¶

Board Specific Configuration

All board specific configurations eg:enabling clock and pin-mux for UART pins are required before calling any driver APIs.By default Board_Init() API supports all initialization sequence for TI supported EVMs. In addition it initializes UART instance for Console/STDIO.Refer PDK Board Support for additional details.Once board specific configuration is complete UART_init() API can be called to initialize driver.

UART Configuration Structure

The UART_soc.c file binds driver with hardware attributes on the board through UART_config structure. This structure must be provided to UART driver. It must be initialized before the UART_init() function is called and cannot be changed afterwards.

For details about individual fields of this library structure, see the PDK doxygen documentation

4.16.2.2. APIs¶

API reference for application:

#include <ti/drv/uart/UART.h>

STDIO API reference for application:

#include <ti/drv/uart/UART_stdio.h>

Open UART

There are three ways to open a UART instance:

1. UART_open()

...
Board_init(boardCfg);
...
UART_socGetInitCfg(UART_INSTANCE, &uart_cfg);
...
UART_socSetInitCfg(UART_INSTANCE, &uart_cfg);
...
UART_Params_init(&params);
...
handle = UART_open(UART_INSTANCE, &params);

At this point UART driver is ready for data transfer on specific instance identified by handle. Application can call UART_read/write API for read/write operation

2. UART_stdioInit() using the default UART parameters

...
Board_init(boardCfg);
...
UART_socGetInitCfg(UART_INSTANCE, &uart_cfg);
...
UART_socSetInitCfg(UART_INSTANCE, &uart_cfg);
...
UART_stdioInit(UART_INSTANCE);

At this point UART driver is ready for data transfer on specific instance. Application can call UART_printf/scanFmt API for read/write operation

3. UART_stdioInit2() using Application specified UART parameters

...
Board_init(boardCfg);
...
UART_socGetInitCfg(UART_INSTANCE, &uart_cfg);
...
UART_socSetInitCfg(UART_INSTANCE, &uart_cfg);
...
UART_Params_init(&params);
...
UART_stdioInit2(UART_INSTANCE, &params);

At this point UART driver is ready for data transfer on specific instance. Application can call UART_printf/scanFmt API for read/write operation

Read/Write APIs

Interrupt:

UART_read(handle,scanPrompt, sizeof(scanPrompt));/* Read API */
...
UART_write(handle, bufferPrompt, sizeof(bufferPrompt));/* Write API */

Or

UART_transactionInit(&transaction);
transaction.buf = (void *)scanPrompt;
transaction.count = sizeof(scanPrompt);
UART_read2(uart, &transaction);
...
UART_transactionInit(&transaction);
transaction.buf = (void *)bufferPrompt;
transaction.count = sizeof(bufferPrompt);
UART_write2(uart, &transaction);

Polling:

UART_readPolling(handle,scanPrompt, sizeof(scanPrompt));/* Read Polling mode API */
...
UART_writePolling(handle, bufferPrompt, sizeof(bufferPrompt));/* Write Polling API */

DMA Usage :

UART driver supports DMA operations to transfer data between

• Memory and RX FIFO for read transfer
• Memory and TX FIFO for write transfer.

DMA Driver is DMA family IP (EDMA and UDMA) and UART IP (V0 and V1) specific. Refer soc/dma/v#/UART_dma.c for these operations. Application need to create DMA handle and update the configuration before UART_init() API.

uartInitCfg[UART_INSTANCE].edmaHandle = UartApp_edmaInit();/* For AM/K1/K2 devices */

or

uartInitCfg[UART_INSTANCE].udmaHandle = UartApp_udmaInit();/* For K3 devices */

UART_init();

Refer “UART_BasicExample_[SOC]_[cpu]DMATestproject” or “UART_DMA_[evm]_[cpu]TestApp” for additional reference. Refer SDK Release Note for supported EVMs.

4.16.3.1. Examples¶