h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 570

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 16 I
Rev. 4.00 Jun 06, 2006 page 516 of 1004
REJ09B0301-0400
SDA
SCL
TRS
Notes on TRS Bit Setting in Slave Mode
From the detection of the rising edge of the 9th clock cycle or of a stop condition to when the
rising edge of the next SCL pin signal is detected (the period indicated as (a) in figure 16.23)
in the slave mode of the I
effective immediately.
However, at other times (indicated as (b) in figure 16.23) the value set in the TRS bit is put on
hold until the next rising edge of the 9th clock cycle or stop condition is detected, rather than
taking effect immediately.
This results in the actual internal value of the TRS bit remaining 1 (transmit mode) and no
acknowledge bit being sent at the 9th clock cycle address receive completion in the case of an
address receive operation following a restart condition input with no stop condition
intervening.
When receiving an address in the slave mode, clear the TRS bit to 0 during the period
indicated as (a) in figure 16.23.
To cancel the holding of the SCL bit low by the wait function in the slave mode, clear the TRS
bit to 0 and then perform a dummy read of the ICDR register.
Data transmission
8
2
C Bus Interface [H8S/2138 Group Option]
Detection of 9th clock
cycle rising edge
9
TRS bit set
(a)
Figure 16.23 TRS Bit Setting Timing in Slave Mode
ICDR dummy read
Restart condition
2
C bus interface, the value set in the TRS bit in the ICCR register is
1
TRS bit setting hold time
2
Address reception
3
(b)
4
5
6
7
Detection of 9th clock
cycle rising edge
8
A
9