OLIMEX© 2017
A20-OLinuXino-LIME2 user's manual
setup by pulling the cable it might break! Furthermore – you might bend the board's or the cable's pins!
Use pliers or other suitable object to disconnect the connectors carefully!
Important: each pair of rows of pins of all GPIO connectors on A20-OlinuXino-LIME2 are swapped
compared to A20-OLinuXino-LIME and A10-OLinuXino-LIME!
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”
6.9.1 GPIO-1 (General Purpose Input/Output) 40pin connector
This connector features the processor signals needed for audio headphones output and microphone input.
Please note that not only the connectors but also the rest of the schematic is missing! You would need to
add resistors and capacitors. The connector also has the signals needed for a VGA output. The official
Linux Debian images include a script that can be used to change the video output to VGA. We don't
provide Android images for the VGA video output.
Microphone signals are: MICIN1 and VMIC
Headphone signals are: HPOUTL, HPCOM and HPOUTR
Please note that part of the VGA and composite video signals are multiplexed (VGA-R, VGA-B,
VGA-G share the same pins with the TVOUT signals).
Composite video signals are located on GPIO-1 connector: TVOUT0 (GPIO-1 pin 20), TVOUT1 (GPIO-
1 pin 22), TVOUT2 (GPIO-1 pin 24); you would also need AGND (GPIO-1 pin 4)
VGA signals are located at GPIO-1 connector and LCD_CON connector: The total of 5 signals you need
for VGA output can be split into two categories:
1) Data signals: VGA-R (AC17); VGA-B (AB16); VGA-G (AC16)
2) Synchronization signals: LCD_VSYNC (AC9) and LCD_HSYNC (AB9)
If you inspect the schematics of a board with VGA connector (like A20-OlinuXino-MICRO or A20-
SOM-EVB) carefully you would notice that there are two extra transistors on the synchronization lines.
Those are transistors meant to shift the levels to 5V. The 3.3V levels from the processor might work but
the standard requires 5V levels of VSYNC and HSYNC. However, if you lead the signals to a 6 pin
header (like the one on the A20 board) you might use the cable for the A20-OlinuXino-MICRO (called
A20-VGA-CABLE). The 6 signals needed are the 5 signals mentioned about plus GND.
A general advice for easier use of the microphone, headphone and VGA interfaces of A20-OLinuXino-
LIME2 is to take a look at the schematics of another board with those interfaces already installed. For
example, those are present in A20-OLinuXino-MICRO. Inspect the schematic carefully.
The signal layout is described on the next page:
Page 34 of 51
