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ML66525 Family User’s Manual
Chapter 5
Port Functions
5 - 39
5.16 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 set as an input (corresponding bits of P15IO = “0”) and the port 15 secondary
function control register (P15SF) is set to “1”, the pin inputs corresponding to those bits will be
pulled-up.
If bit 0 of port 15 is set 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 5-18 shows the configuration of the port 15 data register (P15), port 15 mode register
(P15IO) and the port 15 secondary function control register (P15SF).
000
00
0
1
765
4
321
0
76
5
4
3
2
1
0
76
54
32
10
0
1
0
1
0
1
000
00
000
00
—
P15IO2
P15IO3
P15IO1 P15IO0
P15IO
TXD6
P15SF1
P15SF0
P15SF
P15_3 P15_2 P15_1 P15_0
P15
At reset
TXC6
P15SF2
TXC6
P15SF3
At reset
Address: 00BF [H]
R/W access: R/W
Address: 00C5 [H]
R/W access: R/W
Address: 00C7 [H]
R/W access: R/W
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”.
Not pulled-up
P15_1 input
Primary function
P15_0 output
0 output*
Pulled-up
Secondary function
P15_1 output
SIO6 transmit data output
P15_0 input
SIO6 receive
data input
0 (Input setting)
1 (Output setting)
Not pulled-up
Pulled-up
Not pulled-up
Pulled-up
Not pulled-up
Pulled-up
P15_2 input
SIO6 receive
clock input
P15_3 input
SIO6 transmit
clock input
Primary function
Secondary function
Primary function
Secondary function
Primary function
Secondary function
P15_2 output
SIO6 receive clock output
P15_3 output
SIO6 transmit clock output
——
—
——
—
——
—
Figure 5-18
P15, P15IO, P15SF Configuration