Registers Controlling Serial Interface Csi10 - NEC 78K0 User Manual

14.3 Registers Controlling Serial Interface CSI10

Serial interface CSI10 is controlled by the following four registers.
• Serial operation mode register 10 (CSIM10)
• Serial clock selection register 10 (CSIC10)
• Port mode register 1 (PM1)
• Port register 1 (P1)
(1) Serial operation mode register 10 (CSIM10)
CSIM10 is used to select the operation mode and enable or disable operation.
CSIM10 can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Figure 14-2. Format of Serial Operation Mode Register 10 (CSIM10)
Address: FF80H After reset: 00H R/W
Symbol <7>
CSIM10 CSIE10
CSIE10
0
1
Note 4
TRMD10
Note 5
0
1
Note 6
DIR10
0
1
CSOT10
0
1
Notes 1. Bit 0 is a read-only bit.
2. When using as a general-purpose port, see Caution 3 of Figure 14-3 and Table 14-2.
3. Bit 0 (CSOT10) of CSIM10 and serial I/O shift register 10 (SIO10) are reset.
4. Do not rewrite TRMD10 when CSOT10 = 1 (during serial communication).
5. The SO10 output is fixed to the low level when TRMD10 is 0. Reception is started when data is read
from SIO10.
6. Do not rewrite DIR10 when CSOT10 = 1 (during serial communication).
Caution Be sure to clear bit 5 to 0.
CHAPTER 14 SERIAL INTERFACE CSI10
Note 1
6 5
TRMD10 0
Operation control in 3-wire serial I/O mode
Note 2
Disables operation and asynchronously resets the internal circuit
Enables operation
Receive mode (transmission disabled).
Transmit/receive mode
MSB
LSB
Communication is stopped.
Communication is in progress.
User's Manual U16227EJ2V0UD
4 3
DIR10 0
Transmit/receive mode control
First bit specification
Communication status flag
2 1 0
0 0 CSOT10
Note 3
.
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