9 years, 8 months ago.

LPC824 Power question

Team I am using LPC824 to connect to an external GPS GPRS module. We are seeing a strange occurence. Need you help please.

Our logic is as follows on LPC824

1) Wait for 5 seconds (Give the whole system time to settle on power up) 2) Pull the power key of the GPS GPRS module using a GPIO pin (p0_27) 3) Wait for 5 seconds. 4) Go through process of setup initialize and loop

I have two problems

Problem #1 When in step #1 I power cycle for a short ebough duration (say about 500mS) LPC824 just hangs. It neither restarts nor does it continue with the processing. On our hardware (since its automotive) our capacitance is about 470uF to stop fluctuations. I am not sure if thats causing a problem

Problem #2 If between step #3 and #4 above if i pull the GPIO pin to high module stops.

Please note that i have a 4.7kOhm resistor between the GPIO line and the GPS/GPRS's pwrKey

Appreiciate your help

Best Regards Surendar