
R8C/2C Group, R8C/2D Group
Rev.2.00
Dec 05, 2007
REJ09B0339-0200
16.2
Clock Synchronous Serial I/O with Chip Select (SSU)
Clock synchronous serial I/O with chip select supports clock synchronous serial data communication.
I/O with Chip Select Associated Registers.
NOTE:
1. Clock synchronous serial I/O with chip select has only one interrupt vector table.
Table 16.2
Clock Synchronous Serial I/O with Chip Select Specifications
Item
Specification
Transfer data format
Transfer data length: 8 bits
Continuous transmission and reception of serial data are supported since
both transmitter and receiver have buffer structures.
Operating modes
Clock synchronous communication mode
4-wire bus communication mode (including bidirectional communication)
Master/slave device
Selectable
I/O pins
SSCK (I/O): Clock I/O pin
SSI (I/O): Data I/O pin
SSO (I/O): Data I/O pin
SCS (I/O): Chip-select I/O pin
Transfer clocks
When the MSS bit in the SSCRH register is set to 0 (operates as slave
device), external clock is selected (input from SSCK pin).
When the MSS bit in the SSCRH register is set to 1 (operates as master
device), internal clock (selectable among f1/256, f1/128, f1/64, f1/32, f1/16,
f1/8 and f1/4, output from SSCK pin) is selected.
Clock polarity and phase of SSCK can be selected.
Receive error detection Overrun error
Overrun error occurs during reception and completes in error. While the
RDRF bit in the SSSR register is set to 1 (data in the SSRDR register) and
when next serial data receive is completed, the ORER bit is set to 1.
Multimaster error
detection
Conflict error
When the SSUMS bit in the SSMR2 register is set to 1 (4-wire bus
communication mode) and the MSS bit in the SSCRH register is set to 1
(operates as master device) and when starting a serial communication, the
CE bit in the SSSR register is set to 1 if “L” applies to the SCS pin input.
When the SSUMS bit in the SSMR2 register is set to 1 (4-wire bus
communication mode), the MSS bit in the SSCRH register is set to 0
(operates as slave device) and the SCS pin input changes state from “L” to
“H”, the CE bit in the SSSR register is set to 1.
Interrupt requests
5 interrupt requests (transmit-end, transmit-data-empty, receive-data-full,
overrun error, and conflict error)
(1).
Select functions
Data transfer direction
Selects MSB-first or LSB-first
SSCK clock polarity
Selects “L” or “H” level when clock stops
SSCK clock phase
Selects edge of data change and data download