johndxmurphy
New Member
Hi, I'm working on a small 08M with two LED's and a Piezo horn connected to output 4. On down load of program the piezo sounds and the download fails. I can't find any shorts or opens etc. Any ideas?
Piezo out4 sounds on download
- Thread starter johndxmurphy
- Start date
johndxmurphy
New Member
I disconnected output 4 but still get "Memory verification error - byte 255" or something close to that. Using three brand new Duracell AA batteries. Voltmeter shows about 4.3 or 4.4 volts.
Anyway, I'll maybe desolder leg2 and leg3 and try again. Maybe thats the problem.
Anyway, I'll maybe desolder leg2 and leg3 and try again. Maybe thats the problem.
BeanieBots
Moderator
Double check that your 22k resistor IS 22k. It might be that excess current (limited by the 22k into the internal clamp diode) is pushing up the supply. This would be both audible on the piezo and cause erratic downloads.
BTW "three brand new Duracell AA batteries" should be closer to 4.7v.
Are you sure they are "brand new"? Maybe your meter is a bit out?
BTW "three brand new Duracell AA batteries" should be closer to 4.7v.
Are you sure they are "brand new"? Maybe your meter is a bit out?
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A verification error does show the PICAXE is actually communicating, you wouldn't get this message if not. You can double check this by doing a Firmware check (View>Options>Mode>Firmware).
This message normally implies some kind of power supply/download circuit issue.
This message normally implies some kind of power supply/download circuit issue.
johndxmurphy
New Member
Firmware verification worked. The resistor is red red orange, so should be 22K but haven't verified that yet with a meter.
johndxmurphy
New Member
Continuing to work on this problem, I measured ohms on circuit with chip removed. Between hardware pins 1 and 2 I get about 30K ohms. Between hardware pins 2 and 3 I get about 20K ohms. Same between pins 3 and 4. I guess I expected a complete open, i.e. a huge resistance. Between pins 4 and 5 about 1M ohms. (that's what I expected on the other pins). Between pins 5 and 6 I get about 70K ohms. Between 6 and 7 about 11K ohms. Between 7 and 8 I get about 1M ohm. I seems that the lower resistances on the left side of the chip indicates a problem but I don't know what to expect. I'd appreciate your inputs.
BeanieBots
Moderator
Without knowing the complete circuit, those readings tell much. I'd also guess that from the 1M readings, you were making contact with your fingers. That's about the reading you'd get for dry fingers!
If it's not due to finger contact, then maybe lots of flux left on the board??
Sounds like your 22k is OK.
Time to concentrate on the power supply and/or circuit error.
Your voltage reading is very low for NEW batteries. Try some 'newer' ones even if only to humour me.
If it's not due to finger contact, then maybe lots of flux left on the board??
Sounds like your 22k is OK.
Time to concentrate on the power supply and/or circuit error.
Your voltage reading is very low for NEW batteries. Try some 'newer' ones even if only to humour me.
It sounds like you may have damaged the 08M chip (output 4).
Is the horn a high current type (>20mA) - if so did you buffer it with a transistor (or connect direct). If connected direct you will probably have permanently damaged the internals of output 4 of the chip, which could then give you this strange behaviour.
Is the horn a high current type (>20mA) - if so did you buffer it with a transistor (or connect direct). If connected direct you will probably have permanently damaged the internals of output 4 of the chip, which could then give you this strange behaviour.
johndxmurphy
New Member
What about the resistance between legs 2 and 3 with chip removed and leg3 is now disconnected from piezo. That should be a larger resistance right? If so, could flux cause that? I have been using a lot of flux thinking it was a good thing.
BeanieBots
Moderator
After removing the chip AND the piezo, is ANYTHING else connected to pin3?
If yes, then impossible to say without a FULL circuit diagram.
If no, and you still see ~20k between pin 2 and 3, then there is a cicuit fault.
Excess flux can conduct very slightly. It might account for 1M but only an error could cause 20k.
If yes, then impossible to say without a FULL circuit diagram.
If no, and you still see ~20k between pin 2 and 3, then there is a cicuit fault.
Excess flux can conduct very slightly. It might account for 1M but only an error could cause 20k.