Clock Synchronous Serial I/O Mode - von Gunthard Kraus

R8C/10, R8C/11, R8C/12, R8C/13 Group
Serial I/O Operation (Clock Synchronous Serial I/O Mode)
3.5ms
250µs 250µs
1ms
CLK0
1 2 3 4 10 1
TXD0
1 2 3 4 10 1
RXD0
1 2 3 4 10 1
8µs
CLK0
TxD0 D0 D1 D2
D3 D4 D5 D6 D7
RxD0
D0
D1
D2
D3 D4 D5 D6 D7
Figure 1. Transmit Format
3.1 Pins Used
Table 1. List of Pins Used and Their Functions
Pin name I/O Function
P14/TxD0 Output Serial data output
P15/RxD0 Input Serial data input
P16/CLK0 Output Transfer clock output
3.2 Memory Usage
Table 2. Memory Usage
Memory Usage Size Remarks
ROM 167 bytes In only the main.c module
RAM 21 bytes In only the main.c module
Maximum user stack used 6 bytes sfr_init function: 3 bytes
Cs_sral function: 3 bytes
Maximum interrupt stack used 0 byte Unused
The size of the used memory differs with the C compiler version and compile options. The above applies to the conditions
given below.
• C compiler: M3T-NC30WA V.5.20 Release 1
• Compile option: -g -O -finfo Note - R8C
Note: Unusable in the R8C/Tiny-only free version.
Table 4. RAM Usage and Definition
Symbol Type Size Content
serial_cnt unsigned char 1 byte Transmit/receive data counter
rcv_buf[10] unsigned char 10 bytes Receive buffer
trn_buf[10] unsigned char 10 bytes Transmit buffer
REJ05B0452-0110Z/Rev.1.10 August 2004 Page 2 of 11