OLIMEX© 2018
A20-OLinuXino-MICRO user's manual
6.11 GPIO ports
There are three GPIO ports which are used generally to access unused by the board's peripherals
pins. However, there are exceptions – some of the pins might be used to easily peripherals or their
levels.
Most of the pins are already defined in default operating system images. Some of them can be used
as GPIOs, I2C or SPI without much of a problem. Information on the software usage of GPIO ports
might be found in chapters “2.8 GPIO under Debian” and “2.9 I2C and SPI under Debian”.
6.11.1 GPIO-1 (General Purpose Input/Output) 40pin connector**
The GPIO-1 plastic connector has 14 pins. The signal layout is described below:
GPIO-1 connector
Pin # Signal name
Processor pin
Pin # Signal name
Processor pin
1
+5V
-
2
GND
-
3
+3.3V
-
4
GND
-
5
PG0
F20
6
VOL+_BUT
AB23***
7
PG1
E21
8
VOL-_BUT
AB23***
9
PG2
E20
10
MENU_BUT
AB23***
11
PG3
D21
12
SEARCH_BUT
AB23***
13
PG4
D20
14
HOME_BUT
AB23***
15
PG5
C21
16
ESC_BUT
AB23***
17
PG6
E19
18
ENTER_BUT
AB23***
19
PG7
C20
20
TVOUT3
AB17
21
PG8
D19
22
TVIN0
AC18
23
PG9
C19
24
TVIN1
AB18
25
PG10
D18
26
TVIN2
AA17
27
PG11
C18
28
TVIN3
Y17
29
VGA_HSYNC
AB9*
30
LINEINR
AB21
31
VGA_VSYNC
AC9*
32
LINEINL
AB20
33
VGA-G
AC16*
34
FMINR
Y21
35
VGA-B
AB16*
36
FMINL
Y20
37
VGA-R
AC17*
38
MIC1OUTP
AC22
39
LRADC1
AB22*
40
MIC1OUTN
AC23
*Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handled
properly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).
**It was erroneously named GPIO-4 in the first release of the board.
***All Android buttons are connected to an ADC (LRADC) that uses a divider to determine which button is pressed.
The yellow part of the table shows all the signals shared with the 6-pin VGA connector.
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