UPD784938 Datasheet, PDF (459/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 19 3-WIRE SERIAL I/O MODE
19.3 Control Registers
19.3.1 Clocked serial interface mode register (CSIM, CSIM3)
CSIM and CSIM3 are 8-bit registers that specify the serial interface operation mode (enable/disable), serial clock, etc.
These registers can be read or written to with an 8-bit manipulation instruction or bit manipulation instruction. The CSIM
and CSIM3 format is shown in Figure 19-1.
RESET input clears these registers to 00H.
Figure 19-2. Format of Clocked Serial Interface Mode Register (CSIM) and
Clocked Serial Interface Mode Register 3 (CSIM3)
7
6
5
4
3
2
1
0 Address After reset R/W
CSIM ENCSI SELST DIR CRXE MOD SELCL2 SELCL1 SELCL0 0FF82H 00H R/W
CSIM3 ENCSI3 SELST3 DIR3 CRXE3 MOD3 SELCL32 SELCL31 SELCL30 0FF80H 00H R/W
SELCL SELCL SELCL
n2 n1 n0
(n = 3 with CSIM3 only)
Serial Clock Specification
0
0
0 External clock^{Note 1}
0
0
1 fXX/128
0
1
0 fXX/64
0
1
1 fXX/32
1
0
0 fXX/16
1
0
1 fXX/8^{Note 2}
Other than the above Setting prohibited
MODn N-ch Open-Drain Specification (P32, P33, or P105, P107)
0 Not N-ch open drain
1 N-ch open drain
CRXEn Enables/Disables Serial Interface Receive Operation
0 Reception disabled
1 Reception enabled
DIRn
Serial Interface Bit Transfer Order Selection
0 MSB first
1 LSB first
SELSTn
Transmit Activation Condition Selection
0 Start with a write operation to SIO (serial shift register)
1 Start with a read operation from SIO
ENCSIn Enables/Disables Serial Interface Operation
0 Disabled
1 Enabled
Preliminary User’s Manual U13987EJ1V0UM00
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