Datasheet

674

SAM4S Series [DATASHEET]

11100F–ATARM–29-Jan-14

33.8.4 SPI Transmit Data Register

Name: SPI_TDR

Address: 0x4000800C

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 register in a right-justified format.

 PCS: Peripheral Chip Select

This field is only used if variable peripheral select is active (PS = 1).

If PCSDEC = 0:

PCS = xxx0 NPCS[3:0] = 1110

PCS = xx01 NPCS[3:0] = 1101

PCS = x011 NPCS[3:0] = 1011

PCS = 0111 NPCS[3:0] = 0111

PCS = 1111 forbidden (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 is de-asserted after the transfer of the character written in TD. When CSAAT is set, the communication with

the current serial peripheral can be closed by raising the corresponding NPCS line as soon as TD transfer is 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

76543210