Shift Operation Start/Stop Timing - Fujitsu MB90390 Series Hardware Manual

CHAPTER 22 SERIAL I/O
22.4.3

Shift Operation Start/Stop Timing

To start the shift operation, set the STOP bit to "0" and the STRT bit to "1" in SMCS.
The system may stop the shift operation at the end of transfer or when "1" is set in the
STOP bit.
• Stop by STOP=1 → The system stops with SIR=0 regardless of the MODE bit
• Stop by end of transfer → The system stops with SIR=1 regardless of the MODE bit
Regardless of the MODE bit, the BUSY bit becomes "1" during serial transfer and
becomes "0" during stop or Read/Write standby state. To check the transfer status,
read this bit.
■ Shift Operation Start/Stop Timing
●
Internal shift clock mode (LSB first)
Figure 22.4-3 Shift Operation Start/Stop Timing (Internal Clock)
SCK4
(Transfer start)
STRT
BUSY
SOT4
●
External shift clock mode (LSB first)
Figure 22.4-4 Shift Operation Start/Stop Timing (External Clock)
SCK4
(Transfer start)
STRT
BUSY
SOT4
450
If MODE=0
DO0
If MODE=0
DO0
"1" output
(Transfer end)
DO7 (Data maintained)
(Transfer end)
DO7 (Data maintained)