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8-18
Register: 0xFF21
Multipurpose I/O Bank 3 Enable (MPE3)
Read/Write
7
R
0
0
R
Reserved
MPE3_[3:0]
Multipurpose I/O Bank 3 Enable
These bits control the output enables on the I/O pins
MPIO3_0, MPIO3_1, MPIO3_2, and MPIO3_3. A value of
1 turns on the pin driver, and a value of 0 3-states the
pin. Because the value in this register powers up to all
zeros, the pins will initially be 3-stated at power-up.
These pins also have internal 100 µ A pull-down resistors,
which can be disabled with the
Pull-down Enable (MPPE3)
When the SPEN bit (0xFF05, bit 1) is set, the MPIO3_2
pin is mapped to the TXD serial port function of the
microcontroller core, and the MPIO3_3 pin is mapped to
the RXD serial port function of the microcontroller core.
When the EIEN bit (0xFF05, bit 0) is set, the MPIO3_0
pin is mapped to the EXS0_INT external interrupt
function of the microcontroller core and the MPIO3_1 pin
is mapped to the EXS1_INT external interrupt function of
the microcontroller core.
System Registers
4
3
MPE3_3
Defaults:
0
0
0
2
1
MPE3_2
MPE3_1
0
0
Multipurpose I/O Bank 3
register (0xFF25).
0
MPE3_0
0
[7:4]
[3:0]
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