Power Up reset/execution problem

[lpcware]

Content originally posted in LPCWare by mvinger on Sun Jul 21 09:44:27 MST 2013
I have two boards powered in series (one board receives power and passes it on to second via cable).
Both boards have an LPC812. The board at the end of the power chain is the UI board and is the master over the internal UART interface and the board providing the power is the mainboard as is the UART slave.

On power up, the mainboard LPC812 always powers up and executes its code properly.
The UI board at the end of the power chain must be manually reset externally for it to execute its code.
Is there a power up sequence/rate issue? I did not see any restrictions in the data sheet. The biggest difference on the UI board is has a 5V rotary encoder connected to 2 input pins.

Thank you.
MTV2

[lpcware]

Content originally posted in LPCWare by embd02161991 on Tue Aug 13 15:43:11 MST 2013
Hi ,

Initally , make sure the chip on the UI board is alive on power up. Initialize a port pin and assign a low , high or toggle the signal. Probe the pin to make sure the chip is working on power up. Secondly, you can try to get into the debug mode on both the chips and step the instructions, to ensure if it does the expected operation . If not you would know the location where there is an error. Hope this helps !