
ML66517 Family User’s Manual
Chapter 5
Port Functions
5 – 33
5.15 Port 15 (P15)
Port 15 is a 4-bit I/O port. Each individual bit can be specified as input or output by the port 15 mode register
(P15IO). When output is specified (corresponding bits of P15IO = “1”), the value of the corresponding bits in the
port 15 data register (P15) will be output from their appropriate pins.
In addition to its port function, P15 is assigned secondary functions (such as SIO6 receive data input). If a
secondary function output is to be used, set the corresponding bits of the port 15 mode register (P15IO) and the
port 15 secondary function control register (P15SF) to “1”. If a secondary function input is to be used, reset
corresponding bits of the port 15 mode register (P15IO) to “0” to configure the input mode (same input as the
primary function input).
If the port is configured as an input (corresponding bits of P15IO = “0”) and the port 15 secondary function
control register (P15SF) is set to “1”, inputs will be pulled-up at the pins corresponding to those bits.
If bit 0 of port 15 is configured as a secondary function output (P15IO0 = 1, P15SF0 = 1), the output will be
fixed at “0”, regardless of the value of the port 15 data register.
Figure 5-17 shows the configuration of the port 15 data register (P15), port 15 mode register (P15IO) and the
port 15 secondary function control register (P15SF).
Figure 5-17
P15, P15IO, P15SF Configuration
7
6
5
4
3
2
1
0
P15IO3 P15IO2 P15IO1
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
P15_3
P15_2
P15_1
0
TXC6
P15SF3
RXC6
P15SF2
TXD6
P15SF1
P15IO0
P15_0
P15SF0
0
Not pulled-up
P15_0 input
SIO6 receive
data input
Primary function P15_0 output
1
Pulled-up
0 output*
Not pulled-up
P15_1 input
P15_2 input
SIO6 receive
clock input
P15_3 input
SIO6 transmit
clock input
Primary function P15_1 output
Pulled-up
SIO6 transmit
data output
Not pulled-up
Primary function P15_2 output
Pulled-up
SIO6 receive
clock output
Not pulled-up
P15_3 output
Pulled-up
SIO6 transmit
clock output
0
1
0
1
0
1
0 (Input setting)
1 (Output setting)
P15IO
At reset
P15SF
At reset
P15
At reset
Address: 00C7 [H]
R/W access: R/W
Address: 00C5 [H]
R/W access: R/W
Address: 00BF [H]
R/W access: R/W
Primary function
0 output*: “0” is output, regardless of the value of the port data register
“
” indicates a bit that does not exist. If read, the value will be “0”.
Secondary function