NRF52820-QDAA-R datasheet(252/437 Pages) NORDIC

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Peripherals

START

CPU

ENDTX

ORC

CSN

SCK

MOSI

m-2

m-1

MISO

ENDRX

Figure 100: SPI master transaction

The ENDTX is generated when all bytes in buffer TXD.PTR on page 261 are transmitted. The number of

bytes in the transmit buffer is specified in register TXD.MAXCNT on page 261. The ENDRX event will be

generated when buffer RXD.PTR on page 260 is full, meaning the number of bytes specified in register

RXD.MAXCNT on page 260 have been received. The transaction stops automatically after all bytes have

been transmitted/received. When the maximum number of bytes in the receive buffer is larger than the

number of bytes in the transmit buffer, the contents of register ORC on page 262 will be transmitted

after the last byte in the transmit buffer has been transmitted.

The END event will be generated after both the ENDRX and ENDTX events have been generated.

The SPI master can be stopped in the middle of a transaction by triggering the STOP task. When triggering

the STOP task, SPIM will complete the transmission/reception of the current byte before stopping. A

STOPPED event is generated when the SPI master has stopped.

If the ENDTX event has not already been generated when the SPI master has come to a stop, the ENDTX

event will be generated even if all bytes in the buffer TXD.PTR on page 261 have not been transmitted.

If the ENDRX event has not already been generated when the SPI master has come to a stop, the ENDRX

event will be generated even if the buffer RXD.PTR on page 260 is not full.

A transaction can be suspended and resumed using the SUSPEND and RESUME tasks. When the SUSPEND

task is triggered, the SPI master will complete transmitting and receiving the current ongoing byte before

it is suspended.

6.16.2 Pin configuration

The SCK, MOSI, and MISO signals associated with SPIM are mapped to physical pins according to the

configuration specified in the PSEL.n registers.

The contents of registers PSEL.SCK on page 258, PSEL.MOSI on page 259, and PSEL.MISO on page

259 are only used when SPIM is enabled, and retained only as long as the device is in System ON mode.

The PSEL.n registers can only be configured when SPIM is disabled. Enabling/disabling is done using

4463_156 v1.0

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NRF52820-QDAA-R Datasheet(PDF) 252 Page - Nordic Semiconductor