MC81F4x16
10.2 R1 Port Registers
R1CONH – R14~R17
R1 PORT CONTROL HIGH REGISTER
00D3H
A reset clears the R1CONH register to „55H‟, makes the R17-R14 pins to open-drain output mode.
You can use R1CONH register setting to select input or output mode (open-drain or push-pull) and
enable alternative functions.
When programming the port, please remember that any alternative peripheral I/O function that
defined by the R1CONH register must also be enabled in the associated peripheral module.
7
R1CONH
R/W
R17
6
R/W
5
R16
4
R/W
3
R15
2
R/W
1
R14
0
Reset value: 55H
R/W
R/W
R/W
R/W
00: Schmitt trigger input mode
R17
R17/SCL
01: Output mode, open-drain
10: Alternative function (SCL)
11: Output mode, push-pull
00: Schmitt trigger input mode
R16
R16/SDA
01: Output mode, open-drain
10: Alternative function (SDA)
11: Output mode, push-pull
00: Schmitt trigger input mode
R15
R15/TxD
01: Output mode, open-drain
10: Alternative function (TxD)
11: Output mode, push-pull
00: Schmitt trigger input mode
(RxD mode1,2,3)
R14
R14/RxD
01: Output mode, open-drain
10: Alternative function (RxD mode 0)
11: Output mode, push-pull
78
October 19, 2009 Ver.1.35
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