Intel PXA26X 8.7.1.1 Data Size Select (DSS)

Intel® PXA26x Processor Family Developer’s Manual 8-9
Synchronous Serial Port Controller
8.7.1.1 Data Size Select (DSS)
The 4-bit data size select (DSS) field determines the size of the data that the SSPC transmits and
receives. The data can range from 4 to 16 bits in length. When data is programmed to be less than
16 bits, received data is automatically right-justified and the up per bits in the receive FIFO are
zero-filled by receive logic. Do not left-justify transmit data before placing it in the transm it FIFO.
Table 8-2. SSP Control Register 0 (SSCR0) Bitmap and Bit Definitions
0x4100 0000 SSP Control Register 0 (SSCR0)
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
SCR
SSE
ECS
FRF
DSS
Reset X0x00 0 0 0 0
Bits Name Description
3:0 DSS
DATA SIZE SELECT:
0000 – Reserved, undefined operation
0001 – Reserved, undefined operation
0010 – Reserved, undefined operation
0011 – 4-bit data
0100 – 5-bit data
0101 – 6-bit data
0110 – 7-bit data
0111 – 8-bit data
1000 – 9-bit data
1001 – 10-bit data
1010 – 11-bit data
1011 – 12-bit data
1100 – 13-bit data
1101 – 14-bit data
1110 – 15-bit data
1111 – 16- bit da ta
5:4 FRF
FRAME FORMAT:
00 – Motorola’s Serial Peripheral Interface (SPI)
01 – Texas Instruments’ Synchronous Serial Protocol (SSP)
10 – National Microwire
11 – Reserved, undefined operation
6ECS
EXTERNAL CLOCK SELECT:
0 – On-chip clock used to produce the SSP’s serial clock (SSPSCLK).
1 – SSPEXTCLK is used to create the SSPSCLK.
7 SSE
SYNCHRONOUS SERIAL PORT ENABLE:
0 – SSP operation disabled (pins may function as GPIOs)
1 – SSP operation enabled
15:8 SCR
SERIAL CLOCK RATE:
Value (0 to 255) used to generate transmission rate of SSP.
Bit rate = 3.6864x106 / (2 x (SCR + 1)) or SSPEXTCLK / (2 x (SCR + 1))
31:16 — Reserved