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200ms Pulse on PB5 when Powering Up (Cerb40)


#1

I’m experiencing a a 200ms pulse on the Cerb40 when I power it up. I programmed in the non-ether net firware 4.2.5. I’m also experiencing a decay pulse on the same pin when the unit is powered down.

Can someone tell me where this pulse is generated and how to prevent it from occuring? I have tried several Cerb40s with the same issue.


#2

Do you see the pulse of you add a pull up or pull down resistor on the pin?


#3

I have not tried a resistor becuase I’m configuring the port as output. Currently, there is no code loaded except for the TinyBoot.

Several other ports are not exhibing this behavior. I have exhaustively tested all the ports, but the ones that I found that did not exhibit this behavior were not part of Port B.


#4

Never mind, i checked the schematic for the Cerb40 and found the port has a pull resistor which is causing the pulse on power up. I will switch ports.

Thanks