NRF52811-QCAA-R datasheet(293/444 Pages) NORDIC

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Peripherals

6.19.3 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 87: SPIM EasyDMA Channels

For detailed information regarding the use of EasyDMA, see EasyDMA on page 35.

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 , data loss may occur.

6.19.4 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.

6.19.5 Registers

Base address

Peripheral

Instance

Description

Configuration

0x40003000

SPIM

SPIM1

SPI master 1

0x40004000

SPIM

SPIM0

SPI master 0

Table 88: Instances

Offset

Description

TASKS_START

0x010

Start SPI transaction

TASKS_STOP

0x014

Stop SPI transaction

TASKS_SUSPEND

0x01C

Suspend SPI transaction

TASKS_RESUME

0x020

Resume SPI transaction

EVENTS_STOPPED

0x104

SPI transaction has stopped

EVENTS_ENDRX

0x110

End of RXD buffer reached

EVENTS_END

0x118

End of RXD buffer and TXD buffer reached

EVENTS_ENDTX

0x120

End of TXD buffer reached

EVENTS_STARTED

0x14C

Transaction started

SHORTS

0x200

Shortcuts between local events and tasks

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