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MSM66577 Family User's Manual
Chapter 5 Port Functions
5
5.18 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 5-21 shows the configuration of the port 15 data register (P15), port 15 mode register
(P15IO) and the port 15 secondary function control register (P15SF).
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
000
0
00
0
00
000
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
Secondary function
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
Secondary function SIO6 transmit
data output
Not pulled-up
Primary function
P15_2 output
Pulled-up
Secondary function SIO6 receive
clock output
Not pulled-up
P15_3 output
Pulled-up
Secondary function 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:
R/W access:
00C7 [H]
R/W
Address:
R/W access:
00C5 [H]
R/W
Address:
R/W access:
00BF [H]
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."
Figure 5-21 P15, P15IO, P15SF Configuration