While transmission is halted, the output value of the SO1 pin can be changed by means of the SOL
bit in SCSR1.
10.2.4
Operation in SSB Mode
SSB communication uses two lines, SCL (Serial Clock) and SDA (Serial Data), and enables a
number of ICs to be controlled when connected as shown in figure 10-3.
In SSB mode, a tail mark is attached and transmitted following an 8-bit or 16-bit data transfer.
Either HOLD TAIL or LATCH TAIL can be selected as the tail mark.
SCL
SCK1
H8/3887
Series chip
SDA
SO1
IC-A
IC-B
IC-C
Figure 10-3 Example of SSB Connections
1. Clock
The serial clock can be selected from 8 internal clocks or an external clock, but since the H8/3887
Series chip provides the clock output, an external clock should not be selected. The transfer rate
can be selected with bits CKS2 to CKS0 in SCR1; since this is also the tail mark transfer rate, the
setting should provide for a serial clock cycle of at least 2 µs.
2. Data transfer format
The SCI1 transfer format is shown in figure 10-4. LSB-first transfer is used (i.e. transmission is
performed starting with the least significant bit of the transfer data). A tail mark is added after an
8-bit or 16-bit transfer.
263
ETC [ ETC ]
