HD404639R Datasheet, PDF (98/135 Pages) Renesas Technology Corp – 4-Bit Single-Chip Microcomputer

HD404639R Series
Serial mode register 2B (SM2B: $01C)
Bit
Initial value
Read/Write
Bit name
3
2
1
0
—
0 Undefined 0
—
W
W
W
Not used SM2B2 SM2B1 SM2B0
SM2B2
0
1
R5₃ /SO₂PMOS
On
Off
SM2B0
0
1
Transmit clock division ratio
Prescaler output divided by 2
Prescaler output divided by 4
SM2B1
0
1
Output level control in idle states
Low level
High level
Figure 78 Serial Mode Register 2B (SM2B)
Serial Data Register 2 (SR2L: $01D, SR2U: $01E): This register has the following functions (figures 79
and 80).
• Serial interface 2 transmission data write and shift
• Serial interface 2 receive data shift and read
Writing data in this register is output from the SO₂ pin, LSB first, synchronously with the falling edge of
the transmit clock; data is input, LSB first, through the SI₂ pin at the rising edge of the transmit clock.
Data cannot be read or written during serial data transfer. If a read/write occurs during transfer, the
accuracy of the resultant data cannot be guaranteed.
Serial data register 2 (lower digit) (SR2L: $01D)
Bit
Initial value
Read/Write
Bit name
3
2
1
0
Undefined Undefined Undefined Undefined
R/W
R/W
R/W
R/W
SR23 SR22 SR21 SR20
Figure 79 Serial Data Register 2 (SR2L)
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