NRF9160-SICA-R7 datasheet(227/400 Pages) NORDIC

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Peripherals

6.13.3 Shared resources

The SPI shares registers and other resources with other peripherals that have the same ID as the SPI.

Therefore, the user must disable all peripherals that have the same ID as the SPI before the SPI can be

configured and used.

Disabling a peripheral that has the same ID as the SPI will not reset any of the registers that are shared

with the SPI. It is therefore important to configure all relevant SPI registers explicitly to secure that it

operates correctly.

See the Instantiation table in Instantiation on page 24 for details on peripherals and their IDs.

6.13.4 EasyDMA

The SPIM implements EasyDMA for accessing RAM without CPU involvement.

The SPIM peripheral implements the following EasyDMA channels:

Channel

Type

TXD

READER

TXD

RXD

WRITER

RXD

Table 72: SPIM EasyDMA Channels

For detailed information regarding the use of EasyDMA, see EasyDMA on page 45.

The .PTR and .MAXCNT registers are double-buffered. They can be updated and prepared for the next

transmission immediately after having received the STARTED event.

The SPI master will automatically stop transmitting after TXD.MAXCNT bytes have been transmitted

and RXD.MAXCNT bytes have been received. If RXD.MAXCNT is larger than TXD.MAXCNT, the remaining

transmitted bytes will contain the value defined in the ORC register. If TXD.MAXCNT is larger than

RXD.MAXCNT, the superfluous received bytes will be discarded.

The ENDRX/ENDTX event indicate that EasyDMA has finished accessing respectively the RX/TX buffer in

RAM. The END event gets generated when both RX and TX are finished accessing the buffers in RAM.

In the case of bus congestion as described in AHB multilayer interconnect on page 47, data loss may occur.

6.13.5 Low power

When putting the system in low power and the peripheral is not needed, lowest possible power

consumption is achieved by stopping, and then disabling the peripheral.

The STOP task may not be always needed (the peripheral might already be stopped), but if it is sent,

software shall wait until the STOPPED event was received as a response before disabling the peripheral

through the ENABLE register.

4418_1315 v2.0

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NRF9160-SICA-R7 Datasheet(PDF) 227 Page - Nordic Semiconductor