OLIMEX© 2015
A13-SOM user's manual
CHAPTER 5: CONTROL CIRCUITY
5. Introduction to the chapter
Here you can find information about reset circuit and quartz crystals locations, the power supply
circuit is also briefly discussed.
5.1 Reset
The board can be reset by the RST button. The reset circuit includes Microchip's MCP130T-300I,
designed to keep a microcontroller in reset until the system voltage has reached the proper level and
stabilized.
The board should be turned off either by the standard OS menu or “poweroff” command or any
other software shutdown procedure. After the choice is confirmed it is safe to disconnect the power
supply unit from the board.
5.2 Clocks
24 MHz quartz crystal Q1 is found at pins 91 (X24MOUT) and 92 (X24MIN) of the A13 processor.
5.3 Power supply circuit
The current consumption for A13-SOM when used separately is around 0.1A when connected to a
3.3V voltage source (provided either at GPIO-1's pin 1 or UART1 3.3V pin).
There are several GND pin and pinhole locations. You can use any of the board's GND for powering
purposes.
The typical consumption of the 512 for the board when combined with A13-SOM-WIFI-4GB might
be found below:
Setup
Operating
system
Typical current consumption,
in Amperes, at 5V of voltage
A13-SOM-512 + A13-SOM-WIFI-4GB
Debian
0.45A
A13-SOM-512 + A13-SOM-WIFI-4GB + A13-LCD7-TS
Debian
0.75A
A13-SOM-512 + A13-SOM-WIFI-4GB + A13-LCD7-TS
Android
0.40A
The current consumed usually reaches peaks during start-up when different modules are initialized.
Make sure the supply you provide is capable of powering the board. Note that if there are additional
modules powered by the board, the total power supply requirement would grow. For example,
bigger LCD displays powered via the A13-SOM almost double the current consumption.
For more info on how to power the board refer to chapter “2.3 Powering the board”.
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