RL78/G13 CHAPTER 4 PORT FUNCTIONS
R01UH0146EJ0100 Rev.1.00 218
Sep 22, 2011
4.2.9 Port 8
Port 8 is an I/O port with an output latch. Port 8 can be set to the input mode or output mode in 1-bit units using port
mode register 8 (PM8). When the P80 to P87 pins are used as an input port, use of an on-chip pull-up resistor can be
specified in 1-bit units by pull-up resistor option register 8 (PU8).
Input to the P80 and P81 pins can be specified through a normal input buffer or a TTL input buffer in 1-bit units using
port input mode register 8 (PIM8).
Output from the P80 to P82 pin can be specified as N-ch open-drain output (V
DD tolerance) in 1-bit units using port
output mode register 8 (POM8).
Reset signal generation sets port 8 to input mode.
Table 4-12. Settings of Registers When Using Port 8
Pin Name
Name I/O
PM8× PIM8× POM8×
Alternate Function Setting
Note 2
Remark
1 0
× ×
CMOS input Input
1 1
× ×
TTL input
0
×
0 CMOS output
P80
Output
0
×
1
(SCK10/SCL10 output = 1
Note 1
)
N-ch O.D. output
1 0
× ×
CMOS input Input
1 1
× ×
TTL input
0
×
0 CMOS output
P81
Output
0
×
1
(SDA10 output = 1
Note 1
)
N-ch O.D. output
Input 1
− × ×
0 0 CMOS output
P82
Output
0 1
(TxD1/SO10 output = 1
Note 1
)
N-ch O.D. output
Input 1
− − ×
P83 to P87
Output 0
×
Notes 1. To use P80 to P82 as a general-purpose port when PIOR5 = 1, set serial channel enable status register 1
(SE1), serial output register 1 (SO1) and serial output enable register 1 (SOE1) to the default status.
2. The descriptions in parentheses indicate the case where PIORx = 1.
Remark ×: don’t care
PM8×: Port mode register 8
PIM8×: Port input mode register 8
POM8×: Port output mode register 8
PIOR×: Peripheral I/O redirection register
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