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ML66525 Family User’s Manual
Chapter 5
Port Functions
5 - 41
5.17 Port 20 (P20)
Port 20 is an 8-bit I/O port.
Each individual bit can be specified as input or output by the port
20 mode register (P20IO).
When output is specified (corresponding bits of P20IO = “1”), the
value of the corresponding bits in the port 20 data register (P20) will be output from their
appropriate pins.
In addition to its port function, P20 is assigned a secondary function (external NAND Flash
memory data I/O).
If the secondary function is to be used, set the corresponding bits of the
port 0 mode register (P20IO) and the port 20 secondary function control register (P20SF) to
“1”.
If the port is specified as an input (corresponding bits of P20IO = “0”) and the port 20
secondary function control register (P20SF) is set to “1”, the pin inputs corresponding to those
bits will be pulled-up.
Figure 5-19 shows the configuration of the port 20 data register (P20), port 20 mode register
(P20IO) and the port 20 secondary function control register (P20SF).
7
P20IO7
6
5
4
3
2
1
0
P20IO6
P20IO3 P20IO2 P20IO1 P20IO0
P20IO
7
6
5
4
3
2
1
0
P20SF6
P20SF
7
P20_7
6
5
4
3
2
1
0
P20_6
P20_3 P20_2 P20_1 P20_0
P20
At reset
00
0/1
P20SF3 P20SF2
0
1
P20IO5 P20IO4
P20_5 P20_4
P20SF7
P20SF5 P20SF4
P20SF1P20SF0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
At reset
(EAn = H/L)
At reset
Address: 1B80 [H]
R/W access: R/W
Address: 1B82 [H]
R/W access: R/W
Address: 1B84 [H]
R/W access: R/W
Not pulled-up
P20_0 input
Primary function
P20_0 output
F data 0 I/O
0 (Input setting)
1 (Output setting)
Pulled-up
Secondary function
Not pulled-up
P20_1 input
Primary function
P20_1 output
F data 1 I/O
Pulled-up
Secondary function
Not pulled-up
P20_2 input
Primary function
P20_2 output
F data 2 I/O
Pulled-up
Secondary function
Not pulled-up
P20_3 input
Primary function
P20_3 output
F data 3 I/O
Pulled-up
Secondary function
Not pulled-up
P20_4 input
Primary function
P20_4 output
F data 4 I/O
Pulled-up
Secondary function
Not pulled-up
P20_5 input
Primary function
P20_5 output
F data 5 I/O
Pulled-up
Secondary function
Not pulled-up
P20_6 input
Primary function
P20_6 output
F data 6 I/O
Pulled-up
Secondary function
Not pulled-up
P20_7 input
Primary function
P20_7 output
F data 7 I/O
Pulled-up
Secondary function
Figure 5-19
P20, P20IO, P20SF Configuration