Datasheet

SAM9G20

DS60001516A-page 400  2017 Microchip Technology Inc.

29.7.4 SPI Transmit Data Register

Name: SPI_TDR

Access: Write-only

TD: Transmit Data

Data to be transmitted by the SPI Interface is stored in this register. Information to be transmitted must be written to the transmit data

PCS: Peripheral Chip Select

This field is only used if Variable Peripheral Select is active (PS = 1).

If PCSDEC = 0:

PCS = xxx0NPCS[3:0] = 1110

PCS = xx01NPCS[3:0] = 1101

PCS = x011NPCS[3:0] = 1011

PCS = 0111NPCS[3:0] = 0111

PCS = 1111forbidden (no peripheral is selected)

(x = don’t care)

If PCSDEC = 1:

NPCS[3:0] output signals = PCS

LASTXFER: Last Transfer

0: No effect.

1: The current NPCS will be deasserted after the character written in TD has been transferred. When CSAAT is set, this allows to close

the communication with the current serial peripheral by raising the corresponding NPCS line as soon as TD transfer has completed.

This field is only used if Variable Peripheral Select is active (PS = 1).

31 30 29 28 27 26 25 24

–––––––LASTXFER

23 22 21 20 19 18 17 16

–––– PCS

15 14 13 12 11 10 9 8

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