View Full Version : EEPROM VERIFY ERROR on COM Port 5?

05-14-2008, 02:53 PM

On a circuit board I have built ( and I have made a few of them so far) I am getting the "EEPROM VERIFY ERROR on COM Port 5" error

I have changed the eeprom ( 24LC256) to a another new one but I get the same error
It does say the the PROP CHIP is detected!

Q1) Does anyone know what this means?


Dave M

05-14-2008, 06:54 PM
Hi. David.
Is the EEPROM wired correctly ?
Did you test the EEEPROM Vcc ?
Is working the code with Ctrl-F10 (loading it in RAM) ?
Seems that your eeprom is not recognized by the pchip.



Peter Jakacki
05-14-2008, 08:39 PM
The prop tool does funny things at times, it's timeouts are at the mercy of the host. I had a similar problem with 1.1 and was able to get it going using 1.06 at the time if that makes any sense. But that was then and everything seems to be fine now using 1.1. Try rebooting, you might have a thread hogging CPU time leading to prop tool timeouts.

Another thing is to check the devmgmt or equivalent on the Mac. I found that trying to get the FT232 usb chip to poll faster every 1ms slowed down everything else.


05-15-2008, 07:04 AM

Thanks for the suggestions, but

I just found out what the problem is,

My two resistors for the i2C lines are 5K but my design ask's for 10K,
I will change this later and retest.

( My brother soldered this board together , so don't blame me http://forums.parallax.com/images/smilies/smile.gif )

Sorry to waste anyone's time. :-(


Dave M

Peter Jakacki
05-15-2008, 07:42 AM
Dave, I very much doubt that the 5K resistors are the problem as the 10K value is only nominal, any value from 1K to 10K will work just as well. Besides the pullup on SCL is optional as the prop drives this line high and low, the pullup on SDA is really only needed for when the eeprom acknowledges or sends back any data.


05-15-2008, 09:41 AM
HI Pete,

I remember you mentioning this before, But this is the thing that is different between the boards. I will test later today!


I am using a different "BRAND" of de-coupling capacitor for the EEPPROM ( to what I normally use) , its still marked "104" , could this be causing troubles?


Dave M

Peter Jakacki
05-15-2008, 10:00 AM
What color is the cap?, if it's green it's ok, if it's blue it could be a problem ;)

Ok, really you should check the basics like the power supply and all your connections, maybe you've got a bent pin on the eeprom?

Send us a diagram and/or pic.


05-15-2008, 10:10 AM
HI Pete the cap is yellow/orange its this one


I do have others I got from RTNollet, he has the better ones and its these one I normally use..

Sorry but I don't have any manufacturers part numbers for these.

Dave M

Peter Jakacki
05-16-2008, 06:00 AM
Dave, the capacitor color thing was a joke ;) Don't fret over minor component values in digital circuits, you seemed to be overconfident when you discovered a minor discrepancy yet you haven't tested or understood it. Troubleshooting involves actually solving, crosschecking and cross-crosschecking and understanding the problem, it ain't over till the fat lady sings.

I do get EEPROM verify errors at times but I think it's related to timeouts. I will investigate a little further on this matter and post my findings.


05-16-2008, 09:28 AM
Hi pete,

you can stop laughing now ! :-(

I changed the resistors to 10 K and still made no difference, ( and just for you pete, i made sure I placed the resistors in the right way!!!! , i.e polarity http://forums.parallax.com/images/smilies/smile.gif

If this is a timing issue where does this occur? ( propeller board? PC?,
I have been loading code many times in all day on other boards without this error.

I checked the rest of the board and its all the same as the other one I made, I have changed the eeprom, I have changed the Prop chip.

I can load in the spin code to RAM and this works.


Dave M