Clock; Figure 14.4 Relationship Between Output Clock And Transfer Data Phase (Asynchronous Mode) - Hitachi H8S/2628 Hardware Manual

14.4.3

Clock

Either an internal clock generated by the on-chip baud rate generator or an external clock input at
the SCK pin can be selected as the SCI's serial clock, according to the setting of the C/A bit in
SMR and the CKE0 and CKE1 bits in SCR. When an external clock is input at the SCK pin, the
clock frequency should be 16 times the bit rate used.
When the SCI is operated on an internal clock, the clock can be output from the SCK pin. The
frequency of the clock output in this case is equal to the bit rate, and the phase is such that the
rising edge of the clock is in the middle of the transmit data, as shown in figure 14.4.
SCK
0
TxD
Figure 14.4 Relationship between Output Clock and Transfer Data Phase
Rev. 1.0, 09/02, page 318 of 568
D0 D1 D2 D3
(Asynchronous Mode)
D4 D5 D6 D7
1 frame
1 1
0/1