can't seem to connect to the picaxe

[awander]

I'm am trying to help a friend's son with his picaxe's-he has 3 of them and can't communicate to any of them using the Programming Editor.

I am concentrating on my own tests using the 18X:
We have connected to the picaxe according to the manuals, with the 10K and 22K resistors, and a 4.7K pullup, and a pushbutton to ground, on the Reset pin. I have a 6V supply going to a 7805C regulator, and am getting5.06VDC at the Picaxe.

When I try to connect using the Programming Editopr, I get "Error-Hardware not found on Com1"

I have done the test using a voltmeter on the serin pin, and when I press the Test button, the voltage goes to 5.67V, when I press it again, it drops back down to -0.53V

What should the RS232 port settings be? I can't find that anywhere in the manuals. I have tried various bps rates at 8N1, also tried software handshaking(instead of None)

What should the "Options" be for the 18X? Right now they are at the 4MHz and 16Xgosub, I have tried various other combinations, but thaese settings, combined with the possibilities for the port setting, are too numerous for me to test them all.

I have also tried the rest pin as suggested in teh error box-no joy!

Andy

 

[hippy]

The options ( 4MHz, 16 Gosubs ) will be okay for the 18X and the Programming Editor should override whatever port settings are specified elsewhere and select for itself what it needs to use ( 4800,N,8,1 ). The voltages you supply look correct and as expected.

Check the PICAXE Reset pin. That should be +5V(ish) when the reset button is not pressed, 0V when it is. Also check that the +V and 0V go to the correct 18X pins.

Have any of these PICAXE's ever worked ? Has it been possible to ever download code into them ? Have you had any other PICAXE's working ?

What happens when ( in View->Options ) when you click the "Firmware?" button ?

 

[awander]

Reset pin works as you described.

+5V is on Pin14
GND is on Pin5

None of them have ever worked-but the kid is not sure if he did something wrong and blew them out, or if they were bad when he got them. I just hope i can help him with what(for him) is a large investment.

When I click on the "Firmware?" button, i get the same message "Error-Hardware not found on Com1"

Andy

 

[leftyretro]

Reset pin works as you described.

+5V is on Pin14
GND is on Pin5

None of them have ever worked-but the kid is not sure if he did something wrong and blew them out, or if they were bad when he got them. I just hope i can help him with what(for him) is a large investment.

When I click on the "Firmware?" button, i get the same message "Error-Hardware not found on Com1"

Andy

That doesn't sound like the same error message one gets when the PC picaxe programming editor simply gets no response from the picaxe chip. It sounds like the COM hardware on the PC and the PC picaxe programming editor are not configured correctly to even start the communication process to the picaxe chip. Check that the PC actually has a com port assigned to COM1 or change the picaxe editor to whatever the correct COM hardware address is for your specific PC configuration.

Lefty

 

[awander]

I checked that the there is a Com1 port(which was also confirmed by my reading the correct, changing voltage when using the test in View/Options/Serial Port)

I also made sure that the Programming Editor was set to use Com1.

I changed the port settings in Windows to 4800 8N1.

I even installed the Programming Editor on another PC that I know has a good working Com port, and tried everything again, with the same results.

 

[Dippy]

Getting 3 duffers is almost impossible unless they were badly handled.
Could they have been messed up during the initial 'testing' before you took charge?

A hippy said, any 'manual' adjustments to port settings you make will/should be over-ridden by the Editor software.

• Do you get the same error message if you remove the cable?
• How much current is the PICAXE taking?
• Can you check pins 2 and 3 with a 'scope?
• (Or maybe use a high-bright LED + 10K res down to ground to see if any flashing occurs).
• Are your ground conections OK?
• Do you have any funny loads on the Input/Output pins that may interfere?

Usually when posts like this crop up it turns out to be a wiring error 95% of times. Have you checked connections and that the resistors are OK? (i.e. correct value and that they work).

 

[MORA99]

Isnt 6V a bit low for a 7805 ?

Anyway try the test in options, where you measure the serial in line, and can click a "led" to make it high.

 

[hippy]

The serial port can be further tested by disconnecting the cable from the PICAXE and linking the Tx and Rx pins of the cable - pins 2 and 3 on a 9-way or 25-way cable. Using HyperTerm with 'handshaking : none' or the Terminal within the Programming Editor, what is sent out should be echoed back.

The voltages you gave suggest you have the correct COM port, the 22K/10K is wired correctly ( although worth checking it's not wired as a voltage divider - it isn't ).

That multiple PICAXE's do not work, and on alternative PC's, suggests the problem lies with the construction of the PICAXE boards or the PICAXE's themselves. It would be a very rare occurance to receive a PICAXE which did not work, so initial expermineting could have damaged them. The worst culprits would be reversing the power supply connections, trying to run them from a 9V battery ( anything above 6V would be bad ), or shorting outputs to +V or 0V.

@ MORA99 : 6V is low for a 7805, but if it's a 7805C that may be a low-dropout regulator. If not it may be worthwhile bumping the input voltage up to 9V, although I've seen no problems with voltages less than 5V input to a 7805. Mine simply passed on the voltage less a drop, but it's probably not a good idea to run them this way.

 

[Michael 2727]

Isnt 6V a bit low for a 7805 ?

Thats what I was thinking also.
A standard 78XX regulator needs 2v to 2.5v above the REG voltage
available on the input side at all times to maintain correct
regulation.
Otherwise it could drop out or shut down alltogher.
Are you getting the 6v from batteries ? or an unregulated
AC to DC wallwart/Plugpack ?. The battery usually won't
work unless you have a Low Dropout type regulator.
Even then, only 1 volt above could prove a little dodgy.
( plugpacks tend to allow a little more to reach the rated load capacity )

$0.02¢

 

[BeanieBots]

I have a 6V supply going to a 7805C regulator, and am getting5.06VDC at the Picaxe.

This would suggest the regulator being used is low dropout.
Multiple PCs and 3 no-goers strongly suggests earlier murder, possibly by wrong supply as suggested by Hippy or an as yet undetected circuit fault common to all three.
At this stage, I would completely dismantle any circuitry and start again from scratch. That avoids any self convincing in the existing circuit.
If that fails, then bite the bullet and order a new PICAXE. Young students can be very reluctant to owning up to earlier "playing" especially if it involves cost due to their error.

 

[awander]

It is a 7805C; sorry if i left that part out.

The "young student" readily admits that he may have done something wrong, but we can't figure out what. the cicuit ius just the simple serial circuit for connecting to a PC. When I was working woith him yesterday, he had 2 cjips that he had played with(and not gotten to work) and another chip that he had never hooked up-we tried all 3, with similar results. No communications.

it does indeed seem as if they must be fried, though, as I can't think of anything else to try.

 

[leftyretro]

It is a 7805C; sorry if i left that part out.

The "young student" readily admits that he may have done something wrong, but we can't figure out what. the cicuit ius just the simple serial circuit for connecting to a PC. When I was working woith him yesterday, he had 2 cjips that he had played with(and not gotten to work) and another chip that he had never hooked up-we tried all 3, with similar results. No communications.

it does indeed seem as if they must be fried, though, as I can't think of anything else to try.

Well if you could state your location maybe a near by forum member would let you mail the picaxe chips to them for check-out. That way you could at least half-split the problem to the chips or not. Just buying more chips without knowing more is likely to just lead to more disappointment.

Lefty

 

[awander]

Hi Lefty:

I am in Eastern PA, and the boy who owns the chips is in Western NJ.

Anybody willing to test an 18X for us?

 

[picaxester]

Maybe try just 3 AAs (4.5V) without the regulator, and do you have a bypass capacitor, they seem to really need those.

How long is your download cable?

Does your circuit look like this:
http://i216.photobucket.com/albums/cc41/picaxester/picaxedlcircuit.jpg
(picaxe_manual1.pdf page 27)

 

[awander]

Yes, that's the circuit I am using.

I also tried with the 180 ohm resistor in series with the Serout, as shown in the other app note.

The cable is about 6 feet long.

I have 4 bypass caps on the 7805C, 22pF in parallel with 1oouF on both in and out to ground.

 

[lbenson]

I am in Washington, DC. If you would like mail an 18X and one or more 08Ms to me to test downloading, you can post your email address and I will respond to that. To avoid spam trollers, at least replace "@" with " at " in your posted email address.

 

[awander]

Hi:

Its awander -at- verrex.com

thanks,

Andy

 

[awander]

lbenson:

I wasn't sure if you got to send me the address yet.

My email adress is awander(at)verrex.com

thanks,

 

[lbenson]

email with mailing address is on its way.

 

[Dippy]

Why not send that email info via PM?

I hope the tests are successful.

May I suggest to complete novices that when they order a PICAXE that they also order the cheapest project board that includes the download circuit.
This will remove one variable at least. It won't prevent a gimboid connecting it to the mains, but it could save days of fiddling and posting and waiting.
- I think that's worth a fiver, don't you?

 

[hippy]

Seconded - Good advice

May I suggest to complete novices that when they order a PICAXE that they also order the cheapest project board that includes the download circuit - I think that's worth a fiver, don't you?

Even for non-novices I would venture. At least get some pre-build kit even if it is just the cheapest PICAXE-08 version, and I'd also say it's always worth investing in a genuine Rev-Ed download cable.

There's nothing worse than getting something, building it and finding it doesn't work, and not knowing why, if you've destroyed it or whatever. Likewise if something stops working. At least with a pre-built kit there's always a known reference to compare and test against.

Non-responding PICAXE's are among the worst things in the world ( along with everything else which doesn't do anything when prodded ). There are so many possibilities and so many unknown factors that it is hard to make any guesses as to what may have gone wrong, and there may be multiple problems to overcome.

The only practical solution with non-functioning hardware is to throw it in the bin, write-off the investment and walk away, buy more components and hope it works next time, or spend time investigating not knowing if it will or will not ever work.

It's a problem which afflicts not just new-comers to the PICAXE but old-timers and a lot of development kit. It's always tempting to take short-cuts to save cost ( and how hard can a three resistor interface be to build ? ) but reality doesn't always work out as expected.

It's human nature to get something, plug it in and expect it to work, and it really is frustrating when that does not happen. The days lost are unbearable and discouraging. As Dippy says, the extra cost is often a small price to pay, and insurance if nothing else - By Sod's Law, buy one and your DIY version will work first time, don't and you'll end up buying one sooner or later anyway with extra shipping costs

What would be useful is if Rev-Ed could produce some very simple ( meaning very cheap ) breakout boards for the PICAXE. Wired for download socket and interface components along with any necessary pull-ups and buttons for Reset, holes for crystal where necessary, and with a flying battery connector with blocking diode to prevent reverse polarity problems. All pins can go to one or two rows of holes on the edge in a DIP-like module format. Holes for optional power-on and Tx/Rx Leds would not go amiss.

These could be used "as is" with flying leads, mounted on bread-board, or be used with 0.1" plugs and sockets to plug into other PCB's. They'd fall short of the more complex starter kits but I suspect there are people who do not want what the starter kit provides and see that as a costly investment for little return.

Just the bare PCB's would be useful, a kit of all parts including battery holder even better, pre-assembled, better still. Something a budding 'Eagle entrepreneur' might consider taking on if Rev-Ed don't want to run with it.

 

[Dippy]

Absolutement.

I made some little thingies some time ago which look very much like the Rev-Ed's
http://www.rev-ed.co.uk/docs/AXE029.pdf

it's just a simple adaptor for breadboarding.
Works a treat. Line it up and pop it in. Removes a variable or two eh?
Obv the user has to connect power and xtal (where applicable), which can be a chore if reluctant to read a Data Sheet.

I've never been one to spend a tenner to save a fiver.

A nice evaluation board somewhere between hippy's WIBNI and those you get for PICs would be nice - but it would not be cheap. But it would help for those projects that need finishing by yesterday. And I bet it would cut down the 'Have I blown my PICAXE?' posts.

 

[BeanieBots]

As both a 'professional' and 'hobby' user, I cannot praise the starter kits and project boards enough. For 08/M projects, the cost of the AXE021 is far less than my cost to solder two resistors! Hobby wise, I can usually fit all I need onto the board and simply can't be bothered with doing it myself.
The AXE024 is superb too. Servo lead straight into my proto circuit, no faffing about. Likewise for the bigger AXE020. See Hexapod thread. The 'eyes' and servos just plug straight onto it. Took minutes to wire up and worked first time

 

[lbenson]

Ron Hackett may be laying low after Technical removed his posting, but for U.S. picaxers, he has some very nice and very inexpensive set-ups like this at http://www.jrhackett.net. Bare boards only, tho, so not quite foulup-free. And of course phanderson.com has excellent ready-mades, and links to others.

 

[hippy]

@ lbenson : Yes, that's just the sort of thing I was thinking of. I particularly like the PSU that plugs straight into the breadboard. It's a shame Ron doesn't ship outside the US.

PH Anderson's are a twist on that with their own 'breadboard' built in -

http://www.phanderson.com/picaxe/picaxe08_pcb.jpg

Having just worked with a board like that I'm not convinced they are the easiest to use and would much prefer a more traditional strip-board approach with three holes joined, then a gap, repeat.

 

[awander]

That makes sense to me(and to you) but the kid I'm helping out is 14 years old-remember that to hima $5 looks like a lot of money.

thanks,

 

[Dippy]

Good point Andy. I remember being 14 and keen to get on with my first projects. In fact, keen to the point of impatience.
I also remember my Dad saying to me (after I had popped a chip or two) "Typical, straight at it without reading the instructions!". How right he was. How right he still is.
$5 can be a lot, but how much for 3 PICAXEs? And the time spent.

But, hey, let's be optimistic - maybe if someone checks it then it'll be allright....mmm.
Lessons learnt, perhaps.

 

[awander]

The worst part of it is, he says that he suspected they might have sustained damage in shipping-he said they weren't poacked very well(I didn;t get the details) but he figured he would test them first and not bother reporting anything to wherever he bought them from. I remember doing similar things when I was young, to my (later) distress.

 

[awander]

of course, the 14M, which I tested with him, WAS connected properly, so as long as he didn't forget having used it earlier(he said he kept that one in reserve after having trouble with the 08M and the 18X) i can state with some certainty that we didn't damage it.