Circuit Of Switching In Transfer Bit Order - NEC PD78081(A) User Manual

Internal Bus
LSB-first
MSB-first
SI2
SO2
SCK2
Start bit switching is realized by switching the bit order for data write to SIO2. The SIO2 shift order remains
unchanged.
Thus, switching between MSB-first and LSB-first must be performed before writing data to the shift register.
(4) Transfer start
Serial transfer is started by setting transfer data to the transmission shift register (TXS/SIO2) when the
following two conditions are satisfied.
•
Serial interface channel 2 operation control bit (CSIE2) =1
•
Internal serial clock is stopped or SCK2 is a high level after 8-bit serial transfer.
Caution If CSIE2 is set to "1" after data write to TXS/SIO2, transfer does not start.
Upon termination of 8-bit transfer, serial transfer automatically stops and the interrupt request flag (SRIF) is
set.
CHAPTER 11 SERIAL INTERFACE CHANNEL 2
Figure 11-13. Circuit of Switching in Transfer Bit Order
7
6
1
0
Read/Write Gate
Transmission Shift Register (TXS/SIO02)
Read/Write Gate
SO0 Latch
D Q
169