I’m currently developing a custom board and intend to use G120 module, looking at the Cobra II schematics, without actually owning one I’m not exactly sure about few things:
Can the board be powered only through USB-Client connector, or does it require external power input?
Can both USB(5V) and External(12V) be plugged in at the same time? Which takes priority?
Do I need a power multiplexer or a similar circuit when designing my custom board with G120??
We also made a G120 custom board, and we simply copied the Cobra II circuit at 1st
Later we made a galvanic decoupling using a DC/DC converter and a special chip for USB.
By this we added a jumper, so we can disable powering via USB.
This comes in handy if the boards draws a lot of power, which USB can not supply.
If 12V is removed, then board goes of instead of trying to get enough power from USB.
@ Darko - The G120’s main processor datasheet does not indicate that a 32k crystal is necessary for normal operation of the processor. However, it will be needed if you want to utilize the RTC feature of the G120.