Registers Controlling Serial Interface Csia0; Format Of Automatic Data Transfer Address Count Register 0 (Adtc0) - NEC 78K0 User Manual

(1) Serial I/O shift register 0 (SIOA0)
This is an 8-bit register used to store transmit/receive data in 1-byte transfer mode (bit 6 (ATE0) of serial
operation mode specification register 0 (CSIMA0) = 0).
communication. In addition, after a communication completion interrupt request (INTACSI) is output (bit 0
(TSF0) of serial status register 0 (CSIS0) = 0), data can be received by reading data from SIOA0.
This register can be written or read by an 8-bit memory manipulation instruction. However, writing to SIOA0
is prohibited when bit 0 (TSF0) of serial status register 0 (CSIS0) = 1.
RESET input clears this register to 00H.
Cautions 1. A communication operation is started by writing to SIOA0.
transmission is disabled (bit 3 (TXEA0) of CSIMA0 = 0), write dummy data to the SIOA0
register to start the communication operation, and then perform a receive operation.
2. Do not write data to SIOA0 while the automatic transmit/receive function is operating.
(2) Automatic data transfer address count register 0 (ADTC0)
This is a register used to indicate buffer RAM addresses during automatic transfer. When automatic transfer
is stopped, the data position when transfer stopped can be ascertained by reading ADTC0 register value.
This register can be read by an 8-bit memory manipulation instruction.
RESET input clears this register to 00H. However, reading from ADTC0 is prohibited when bit 0 (TSF0) of
serial status register 0 (CSIS0) = 1.
Figure 17-2. Format of Automatic Data Transfer Address Count Register 0 (ADTC0)
Address: FF97H After reset: 00H
Symbol 7
ADTC0
0

17.3 Registers Controlling Serial Interface CSIA0

Serial interface CSIA0 is controlled by the following eight registers.
• Serial operation mode specification register 0 (CSIMA0)
• Serial status register 0 (CSIS0)
• Serial trigger register 0 (CSIT0)
• Divisor selection register 0 (BRGCA0)
• Automatic data transfer address point specification register 0 (ADTP0)
• Automatic data transfer interval specification register 0 (ADTI0)
• Port mode register 14 (PM14)
• Port register 14 (P14)
CHAPTER 17 SERIAL INTERFACE CSIA0
R
*
6 5 4
0 0 ADTC04
User's Manual U15947EJ2V0UD
Writing transmit data to SIOA0 starts the
3 2
ADTC03 ADTC02 ADTC01
Consequently, when
1 0
ADTP00
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