Operation Of Serial Interface Csia0; Operation Stop Mode - NEC 78K0 User Manual

17.4 Operation of Serial Interface CSIA0

Serial interface CSIA0 has the following three modes.

• Operation stop mode

• 3-wire serial I/O mode
• 3-wire serial I/O mode with automatic transmit/receive function
17.4.1 Operation stop mode
Serial communication is not executed in this mode. Therefore, the power consumption can be reduced. In addition,
the P142/SCKA0, P143/SIA0, and P144/SOA0 pins can be used as ordinary I/O port pins in this mode.
(1) Register used
The operation stop mode is set by serial operation mode specification register 0 (CSIMA0). To set the
operation stop mode, clear bit 7 (CSIAE0) of CSIMA0 to 0.
(a) Serial operation mode specification register 0 (CSIMA0)
This is an 8-bit register used to control the serial communication operation.
This register can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Address: FF90H
CSIMA0
390
CHAPTER 17 SERIAL INTERFACE CSIA0
After reset: 00H R/W
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CSIAE0 ATE0 ATM0
CSIAE0 Control of CSIA0 operation enable/disable
0
CSIA0 operation disabled (SOA0: Low level, SCKA0: High level) and
asynchronously resets the internal circuit
User's Manual U15947EJ2V0UD
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MASTER0 TXEA0 RXEA0
*
DIR0 0