chip won't work properly when USB program cable is disconnected

shmow

I've written and tested a program with the prop, and everything is fine.
But, when I disconnect the programming cable (USB) and test functionality the
chip seems to stall and stop working.
Here are some details about my setup:
-I'm using the PE kit
-the code was downloaded to the·EEPROM
-instead of a battery I have jumpered to the power supply of a separate prop demo board
-the loads are not too demanding - 5 LEDs, 1 piezo and 3 74HC595s each feeding a 7-seg display
I've seen in the forum a similar problem but I can't find it.

Any guidance?

Rayman

Hmm... Maybe it's the ground? Perhaps you didn't hook up a ground wire and the USB connection is your only ground?

Paul Baker

http://forums.parallax.com/showthread.php?p=717842

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

shmow

Thanks for the replies.
I followed the thread (link provided in Paul Baker's reply) and found the answer.
I connected a 1k ohm pull-up resistor to pin 30 of the prop.
Problem solved - thanks for the help.
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