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Author Topic: $50 Robot - Pin1 supposed to have positive voltage?  (Read 1042 times)

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Offline VegaObscuraTopic starter

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$50 Robot - Pin1 supposed to have positive voltage?
« on: October 07, 2010, 07:52:23 PM »
I'm building the $50 robot and its all finished except I haven't gotten all the kinks worked out, and I haven't gotten the servos in the mail yet.  I'm up to the programming stage and I can't get past error -24.  I know this is a very common error and there are a lot of potential causes.  I'm checking every connection on my board and everything that is supposed to be connected is.  Now I'm trying to make sure that everything that isn't supposed to be connected isn't.  I plugged the battery in and touched one side of my multimeter to gnd and started checking each pin for a charge where there shouldn't be one.  Everything checked out fine with the possible exception of pin1.  For some reason, it has a positive charge of 5v.  I don't know if this is something that is supposed to be happening or not.  Can someone confirm that this should or should not be happening?

Edit: I know I'm using the correct COM port.  My computer only has a single com port, and it is labeled as COM2 in the device manager.  I'm using a serial dongle programmer, and the atmega I'm using is an atmega88.  I set ponyprog to use COM2, and selected atmega88 from the list, instead of atmega8.
« Last Edit: October 07, 2010, 08:36:48 PM by VegaObscura »

Offline cyberfish

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Re: $50 Robot - Pin1 supposed to have positive voltage?
« Reply #1 on: October 07, 2010, 10:10:21 PM »
Have you tried looking at the datasheet for the chip you are using?

Offline VegaObscuraTopic starter

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Re: $50 Robot - Pin1 supposed to have positive voltage?
« Reply #2 on: October 08, 2010, 05:33:06 AM »
What should I be looking for in the datasheet?  The pin diagram is exactly the same as the atmega8.

This is what the datasheet says about pin1:

Quote
If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical characteristics
of PC6 differ from those of the other pins of Port C.
If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level on this pin
for longer than the minimum pulse length will generate a Reset, even if the clock is not running.
The minimum pulse length is given in Table 28-12 on page 323. Shorter pulses are not guaranteed
to generate a Reset.

Offline Razor Concepts

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Re: $50 Robot - Pin1 supposed to have positive voltage?
« Reply #3 on: October 08, 2010, 06:54:03 AM »
Pin 1 is the reset pin, if its high it means that the microcontroller is not in reset state - so yes, 5v is correct for pin 1. Brining it low will reset the microcontroller.

 


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