SAM7X128_14 Datasheet, PDF (261/662 Pages) ATMEL Corporation – ARM-based Flash MCU

28.7.4 SPI Transmit Data Register
Name:
SPI_TDR
Access Type:
Write-only
31
30
29
–
–
–
23
22
21
–
–
–
15
14
13
7
6
5
28
27
–
–
20
19
–
12
11
TD
4
3
TD
26
25
–
–
18
17
PCS
10
9
2
1
24
LASTXFER
16
8
0
• 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 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).
SAM7X Series [DATASHEET]
6120K–ATARM–11-Feb-14
261