Slave Transmit Operation - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

16.4.4

Slave Transmit Operation

In slave transmit mode, the slave device outputs the transmit data, while the master device outputs
the receive clock and returns an acknowledge signal. For slave transmit mode operation timing,
refer to figures 21.9 and 21.10.
The transmission procedure and operations in slave transmit mode are described below.
1. Set the ICE bit in ICCRA to 1. Set the MLS and WAIT bits in ICMR and the CKS3 to CKS0
bits in ICCRA to 1. (Initial setting) Set the MST and TRS bits in ICCRA to select slave receive
mode, and wait until the slave address matches.
2. When the slave address matches in the first frame following detection of the start condition,
the slave device outputs the level specified by ACKBT in ICIER to SDA, at the rise of the 9th
clock pulse. At this time, if the 8th bit data (R/:) is 1, the TRS in ICCRA and TDRE in ICSR
are set to 1, and the mode changes to slave transmit mode automatically. The continuous
transmission is performed by clearing TDRE after writing transmit data to ICDRT every time
TDRE is set.
3. If TDRE is set after writing last transmit data to ICDRT, wait until TEND in ICSR is set to 1,
with TDRE = 1. When TEND is set, clear TEND.
4. Clear TRS for the end processing, and read ICDRR (dummy read). SCL is free.
5. Clear TDRE.
Rev. 1.0, 09/01, page 725 of 904