EM357-RTR datasheet(71/241 Pages) SILABS

71 / 241 page

Rev 1.3

8.2. Configuration

Before using a serial controller, configure and initialize it as follows:

1. Set up the parameters specific to the operating mode (master/slave for SPI, baud rate for UART, etc.).

2. Configure the GPIO pins used by the serial controller as shown in Tables 8.1 and 8.2.



"7.2. Configuration" on page 51 shows how to configure GPIO pins.

3. If using DMA, set up the DMA and buffers. This is described fully in "8.7. DMA Channels" on page 101.

4. If using interrupts, select edge- or level-triggered interrupts with the SCx_INTMODE register, enable the

desired second-level interrupt sources in the INT_SCxCFG register, and finally enable the top-level SCx

interrupt in the NVIC.

5. Write the serial interface operating mode (SPI, TWI, or UART) to the SCx_MODE register.

Table 8.1. SC1 GPIO Usage and Configuration

PB1

PB2

PB3

PB4

SPI - Master

SC1MOSI

Alternate Output

(push-pull)

SC1MISO

Input

SC1SCLK

Alternate Output

(push-pull)

(not used)

SPI - Slave

SC1MISO

Alternate Output

(push-pull)

SC1MOSI

Input

SC1SCLK

Input

SC1nSSEL

Input

TWI - Master

SC1SDA

Alternate Output

(open-drain)

SC1SCL

Alternate Output

(open-drain)

(not used)

UART

TXD

Alternate Output

(push-pull)

RXD

Input

nCTS

Input1

nRTS

Alternate Output

(push-pull)*

*Note:

used if RTS/CTS hardware flow control is enabled.

Table 8.2. SC2 GPIO Usage and Configuration

PA0

PA1

PA2

PA3

SPI - Master

SC2MOSI

Alternate Output

(push-pull)

SC2MISO

Input

SC2SCLK

Alternate Output

(push-pull)

(not used)

SPI - Slave

SC2MOSI

Input

SC2MISO

Alternate Output

(push-pull)

SC2SCLK

Input

SC2nSSEL

Input

TWI - Master

(not used)

SC2SDA

Alternate Output

(open-drain)

SC2SCL

Alternate Output

(open-drain)

(not used)

EM357-RTR Datasheet(PDF) 71 Page - Silicon Laboratories

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