Synchronous Mode - NEC PD703114 User Manual

10.3.6 Synchronous mode

The synchronous mode can be set with the ASCK1 pin, which is the serial clock I/O pin.
The synchronous mode is set with the MOD bit of the ASIM11 register, and the serial clock to be used for
synchronization is selected with the SCLS bit of the ASIM10 register.
In the synchronous mode, external clock input is selected when the value of the SCLS bit is 0 (default), and the
serial clock output is selected in the case of all other settings. Therefore, when performing settings, make sure that
outputs between connection nodes do not conflict.
In the synchronous mode, the falling edge of the serial clock is used as the transmission timing, and the rising edge
as the reception timing, but transmit data is output with a delay of 1 system clock (serial clock) (in the external clock
synchronous mode, the maximum delay is 2.5 system clocks).
Figure 10-21. Transmission/Reception Timing in Synchronous Mode
ASCK1
Output data
Start
(TXD1)
Input data
(RXD1)
On the data output side, the data changes at the falling edge of the serial clock output.
On the data input side, the data is latched at the rising edge of the serial clock output.
Serial clock output continues as long as the setting is not canceled.
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CHAPTER 10 SERIAL INTERFACE FUNCTION
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