Software description

AN4457

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DocID026046 Rev 1

2.4

UART emulator peripherals and main functions

2.4.1

Peripheral settings

This section describes the configuration of the peripherals used inside the emulator.

•

GPIO

–

BSRR and IDR are used as destination and source registers for DMA transfers.

–

Two pins must be configured as input and output by the user application.

–

The input pin mode is configured as an EXTI line with falling edge detection.

•

DMA2

–

Channel 6 and stream 1 are used for transmission.

–

Channel 6 and stream 2 are used for reception.

–

The transfer is performed by words.

–

DMA transfer complete interrupt is used at the end of frame transfers.

•

Timer 1

–

Timer channel 1 is configured as capture compare for DMA transmit requests.

–

Timer channel 2 is configured as capture compare for DMA receive requests.

–

No clock division: CKD[1:0] =00.

–

No prescaler: PSC[15:0]=0.

•

SRAM

Four SRAM buffers are used to format data:

–

uint16_t pFirstBuffer_Tx[12] and uint16_t pSecondBuffer_Tx[12] are the buffers

for formatting data in transmission mode.

–

uint16_t pFirstBuffer_Rx[12], uint16_t pSecondBuffer_Rx[112 are the buffers for

formatting data in reception mode.

2.4.2

Initialization and configuration function

The initialization of the UART is performed by HAL_UART_Emul_Init function which allows

to:

•

setup the following UART parameters:

–

Baudrate

–

Frame length

–

Stop bit

–Parity.

•

enable clocks for all the peripherals used: Timer, DMA, GPIOs

•

configure the DMA: channel, stream, mode, TC interrupt,...

•

configure the Timer: channel, period,...