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Rev.1.10 Jul 01, 2005 page 154 of 318
REJ09B0124-0110
M16C/6N Group (M16C/6NK, M16C/6NM) 14. Serial I/O
Under development
This document is under development and its contents are subject to change.
14.1.3 Special Mode 1 (I
2
C Mode)
I
2
C mode is provided for use as a simplified I
2
C interface compatible mode. Table 14.10 lists the specifications
of the I
2
C mode. Figure 14.23 shows the block diagram for I
2
C mode. Table 14.11 lists the registers used
in the I
2
C mode and the register values set. Table 14.12 lists the functions in I
2
C mode. Figure 14.24
shows the transfer to the UiRB register and interrupt timing.
As shown in Table 14.12, the microcomputer is placed in I
2
C mode by setting the SMD2 to SMD0 bits to
“010b” and the IICM bit to “1”. Because SDAi transmit output has a delay circuit attached, SDAi output
does not change state until SCLi goes low and remains stably low.
Table 14.10 I
2
C Mode Specifications
Item Specification
Transfer Data Format Transfer data length: 8 bits
Transfer Clock • During master
The CKDIR bit in the UiMR register = 0 (internal clock) : fj/ 2(n+1)
fj = f1SIO, f2SIO, f8SIO, f32SIO. n: Setting value of the UiBRG register 00h to FFh
• During slave
The CKDIR bit = 1 (external clock) : Input from SCLi pin
Transmission Start Condition Before transmission can start, the following requirements must be met
(1)
• The TE bit in the UiC1 register = 1 (transmission enabled)
• The TI bit in the UiC1 register = 0 (data present in the UiTB register)
Reception Start Condition Before reception can start, the following requirements must be met
(1)
• The RE bit in the UiC1 register = 1 (reception enabled)
• The TE bit in the UiC1 register = 1 (transmission enabled)
• The TI bit in the UiC1 register = 0 (data present in the UiTB register)
When start or stop condition is detected, acknowledge undetected, and acknowledge
detected
Error Detection Overrun error
(2)
This error occurs if the serial I/O started receiving the next data before reading the
UiRB register and received the 8th bit of the next data
Select Function • Arbitration lost
Timing at which the ABT bit in the UiRB register is updated can be selected
• SDAi digital delay
No digital delay or a delay of 2 to 8 UiBRG count source clock cycles selectable
• Clock phase setting
With or without clock delay selectable
Interrupt Request
Generation Timing
i = 0 to 2
NOTES:
1. When an external clock is selected, the conditions must be met while the external clock is in the high state.
2.If an overrun error occurs, the value of UiRB register will be indeterminate. The IR bit in the SiRIC
register does not change.