Haribabu said:
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Decoupling is done at the Supply pins of strip connector on the main board with 1uF Tantalum and 0.1 ceramic in parallel. Separate ground line for analog circuit.


If that is the only supply decoupling done then you have some work to do!! Every chip must be decoupled and bypassed right at the VCC and GND pins. This is even more important for your 'F124 chip which MUST have bypass done across the VCC / GND pairs on each side of the chip where a set of power pins enters the device. The picture below shows how this is done.



Michael Karas