my picaxe/board wont work..

[robbiegrove]

hi i just bought a picaxe 18x chip and a board, i dont believe it was actually one of the official picace.co.uk ones, but here is the circuit to give you a brief idea.. http://www.oatleyelectronics.com/kits/Notes/k193.zip the circuit looks pretty dodgy to me but i made it up anyway.. soldered and plugged it all in and it wouldnt work!

i tried testing for voltage on the outer voltage rail but nothing.. i rearranged it so basically now it skips the resistors and capacitors because im using a regulated power supply anyway.. now i get voltage! but then i try and iterface it to the programming software and it cant find it! it pops up with an error box saying it cant connect, ive tried it on 3 different com ports
ive checked the each wire of the com port out and their fine. i even added a status LED and the com port i trying to communicate with it.. but nothin:/

 

[hippy]

Caveat emperor - You're not the first ...

http://www.rev-ed.co.uk/picaxe/forum/Topic.asp?topic_id=1022&forum_id=8

Check the resonator caps, and try moving the resonator closer to the pins.

 

[manuka]

PLEASE POST IN CORRECT FORUM - this is the "wish list" one !

Sad to say,but that general purpose 2003 Picaxe PCB of Oatley's has a design fault, & will NOT work unless tracks are altered manually. By now they should have at least supplied correction details ? Grr ... see =>http://www.oatleyelectronics.com/kits/Notes/k193_errata.gif
But why a resonator? 18A/Xs of course have the oscillator inbuilt!

Edited by - Stan. Swan on 4/11/2004 1:16:01 AM

 

[robbiegrove]

yes, i did check the eratta image before and i have the "updated" version.. and no i dont have anything in the resonator/crystal spot because i read all the picaxe 18x manuals and info on them before i put the kit together..

i did found that the resistor i was using to go between reset pin and ground wasnt 4k7 (my fault i didnt look at colours properly) and i will have to buy one on tuesday, ill keep you informed if it works or not.. another thing on the serial input isnt there supposed to be a 22k resistor on the serial in BEFORE there is a 10k resistor in parallel going to serial 0v? because on this board it has the 10k resistor then 22k

 

[hippy]

The resistors are correct; they do not form a voltage divider as such ...

http://www.rev-ed.co.uk/picaxe/forum/topic.asp?topic_id=1149

 

[robbiegrove]

what would happen if you put the serialinput straight into the serin pin without any resistors? because i did this while testing and wondering if that could be the cause for all my failing experiments to get the board chip to work.. or is it because i dont have the reset pin grounded at all? im sorry for being a noob :/

 

[hippy]

The effect of pushing PC RS232 straight into the PICAXE Serial In leg could be as extreme as destroying the PICAXE completely and even damaging the PC's Serial Port.

If you've used a desktop PC then you may well have destroyed the PICAXE because the PC puts out +12V/-12V. If you used a laptop which puts out +5V/0V then you might be okay, but no guarantees.

The Reset/MCLR leg needs to be permanently pulled-up to +V via a 4K7, and the leg only ever needs shorting to 0V to peform a Manual Reset; powering-off, wait, then powering-up usually works, but a reset button from leg to 0V is often useful.

Don't worry about being a Newbie, everyone has to start somewhere. If you have blown up the PICAXE, you'll just have to put it down to experience and learn from it; the K193 board is not one I would recommend for inexperienced PICAXE / PICmicro users.

 

[pittuck]

i consider myself intermediate, i blew a servo the other day, something very hard to achive