
R8C/14 Group, R8C/15 Group 15. Clock Synchronous Serial I/O with Chip Select (SSU)
Rev.2.10 Jan 19, 2006 Page 140 of 253
REJ09B0164-0210
15. Clock Synchronous Serial I/O with Chip Select (SSU)
The serial data of the clock synchronous can communicate for the clock synchronous serial I/O with chip
select (hereinafter referred to as SSU). Table 15.1 shows a SSU Specification and Figure 15.1 shows a
Block Diagram of SSU.
Figure 15.2 to 15.8 show SSU Associated Registers.
NOTES:
1. The interrupt vector table is one of the SSU.
2. When setting to the slave device, do not transmit continuously.
Table 15.1 SSU Specification
Item Specification
Transfer Data Format • Transfer-data length 8 bits
Continuous transmit and receive of serial data are enabled since both
transmitter and receiver have buffer structure.
(2)
Operating Mode • Clock synchronous communication mode
• 4-wire bus communication mode (including bidirectional communication)
Master / Slave Device Selectable
I/O Pin 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 Clock •When the MSS bit in the SSCRH register is set to “0” (operates as slave
device), external clock can be selected.
• When the MSS bit in the SSCRH register is set to “1” (operates as master
device), internal clock (selects from φ/256, φ/128, φ/64, φ/32, φ/16, φ/8 and φ/4
and outputs from SSCK pin) can be selected.
• Clock polarity and phase of SSCK can be selected.
Receive Error Detection • Overrun error
Overrun error occurs during receive and completes by error. While the RDRF
bit in the SSSR register is set to “1” (data in the SSRDR register) and
completing the next serial data receive, the ORER bit is set to “1”.
Multimaster Error
Detection
• Conflict error
While 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 Request 5 interrupt requests (transmit-end, transmit-data-empty, receive-data-full,
overrun error and conflict error).
(1)
Select Function • 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
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