NRF9160-SICA-R7 datasheet(242/400 Pages) NORDIC

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Peripherals

If the CPU is not able to reconfigure the TXD.PTR and RXD.PTR between granted transactions, the same

TX data will be clocked out and the RX buffers will be overwritten. To prevent this from happening, the

END_ACQUIRE shortcut can be used. With this shortcut enabled the semaphore will be handed over to the

CPU automatically after the granted transaction has completed, giving the CPU the ability to update the

TXPTR and RXPTR between every granted transaction.

The ENDRX event is generated when the RX buffer has been filled.

The RXD.MAXCNT register specifies the maximum number of bytes the SPI slave can receive in one

granted transaction. If the SPI slave receives more than RXD.MAXCNT number of bytes, an OVERFLOW will

be indicated in the STATUS register and the incoming bytes will be discarded.

The TXD.MAXCNT parameter specifies the maximum number of bytes the SPI slave can transmit in one

granted transaction. If the SPI slave is forced to transmit more than TXD.MAXCNT number of bytes, an

OVERREAD will be indicated in the STATUS register and the ORC character will be clocked out.

The RXD.AMOUNT and TXD.AMOUNT registers are updated when a granted transaction is completed.

The TXD.AMOUNT register indicates how many bytes were read from the TX buffer in the last transaction,

that is, ORC (over-read) characters are not included in this number. Similarly, the RXD.AMOUNT register

indicates how many bytes were written into the RX buffer in the last transaction.

DEF

CPU

Free

CPUPENDING

CPU

Ignored

Granted

Ignored

DEF

CPU

Free

DEF

SPIS

SPI master can use the DEF character to

stop the transaction as soon as possible

if the transaction is not granted.

Figure 76: SPI transaction when shortcut between END and ACQUIRE is enabled

4418_1315 v2.0

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NRF9160-SICA-R7 Datasheet(PDF) 242 Page - Nordic Semiconductor