Let's Make Robots!

wiping my picaxes....

I seem to have wiped two picaxe 18X chips in the last two weeks - my circuits are fine, they work, but occasionally when I do SOMETHING (I have only wiped them twice, and so I don't know what it is that I'm doing...) they get wiped - no bang, no smoke, no smell, no heat, just nothing.

 

So - how easy is it to wipe a picaxe 18x? I seem to be doing it with horrifying regularity - are they really that fragile?

E.

 

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Thanks oddbot. I'll put these into a circuit and try it out. the space inside my robot is getting smaller and smaller....

 

I've had a picaxe lockup and not respond to reprograming due to poor power supply. Read this tip/walkthrough on power regulation.

Okay!. so BOTH of my picaxes are working now! Thanks to your circuit and a bit more hacking away.

The situation was this;

1. chips lock up at some time in the past.

2. I attempt to hard reset using the methods in the manual, but nothing seems to work. An important point here is that I try the reset using a regulated 9v battery (using an axe stack, where the instructions say that I should), and then I also try a 5V transformer in a nice plastic package (so I assumed it was filtered etc...)

3. To check if the battery or transformer are working and not causing problems, I try to program a new chip - it is possible, and so I assume that the battery and the transformer are both adequate - therefore (I assume that) the problem is the chip.

So now, I try a FRESH 9V battery, hooked to my axestack -and indeed the chips were locked up. My LED is flashing nicely as before.

 

My conclusions?

1. If the battery can power a chip for programming and operation, it DOES NOT mean that it is also able to unlock a chip. I must use a fresh one witha bit of fancy filtering.

2. Despite the transformer having a nice pretty plasic case, it is probably not noise-filtered very well.


So - thanks for your tips oddbot.
Thanks for sharing, I'm sure this will help a lot of people in the future.

In order to wipe the memory, amonst other things you need to apply about 13V to a certain pin.

What makes you think they are wiped and not locked up? 

First question, have you got a stable regulated 5V supply? If you don't have suitable bypass capacitors then a 5V regulator will be unstable.

Have you disabled brown out detect?

Have you got suitable noise filtering?

Have you read the manual concerning hard resets and downloads? 

 

okay, I'm certainly not applying 13 volts to anything, so this sounds like good news - I had an email exchange with the picaxe guys, and I got the impression that I had simply erased the bootloader program on the chip.

 To respond to your suggestions.

1. No I definitely dont have brownout detect

2. Well, I was using a dc batt, and I have something like a 40uF cap across the power supply: vcc=>gnd -otherwise I use a ~5V transformer (admittedly, I haven't looked at the kinds of filterng the transf. has..)

3.  I've done the hard reset a few times, per the manual -just in case, but it remains stubbornly unresponsive..

 

Thanks for your suggestions!

E.

 

what do you mean by  wiped? like killing them? if so, are you pulling or pusing too much current/voltage through them? what exactly is the setup that you're using...?

The event is something like this:

picaxe in my robot, it's working, doing robot things. I might plug it into the computer to read the feedback via the sertxd commands in my code.

on the latest occasion, after plugging in the cable to the robot, I seem to have wiped it - it's invisible to the computer. picaxe seems to have turned into a brick of nothing. It appears that I've turned it from a picaxe, into a regular pic (although I don't know how to check that this is what I have done - other than the observations I mention above).

Now, I don't know exactly what I did - perhaps I tried to plug/unplug the cable while power was still on to the robot, and perhaps i shorted somthing while I was plugging it in. Suffice to say that whatever I did, I've done it twice, now I have two dead picaxe18X chips!, and only two left!

 It's strange, because I've done worse things to them in the past - such as putting the chip in the wrong way round (so power goes to the gnd pin, or connected diodes straight to gnd, with no resistor in series. so I was under the impression there were a little more robust, but like I said, I don't know exactly what I did, I just wanted to know if other people were wiping their picaxes with a similar kind of regularity...

 

Sounds like you haven't read the manual concerning hard resets.