Introducing myself

[jledger]

Hi gang. My name is Jeff Ledger, I'm the moderator for Petscii Forums @ http://forums.petscii.com (a retro computer and C64DTV hacking) and discovered the PICAXE while looking a recent project on hackaday.com and something someone posted to my forum. After a couple hours of reading and downloading the free software I'll have to admit I "got the bug" and ordered a solderless breadboard kit with the 08M and a 18X from Ebay last night. While a newbie at microprocessor programming, I do understand a couple programming languages, and logic systems. (And to think I almost bought that $80 basic stamp kit from Radio Shack.. what a waste..)

I've got a couple ideas for using the 18X as a controller to send data to the MOS6581 SID (the 3 voice sound chip from the C64) and see if I can send the right data to create some retro sounds from a combination of modern/oldskool technology. Also if I understand correctly, it almost looks like someone to mix a combination of the 18X (or higher) to perhaps create a functional microcomputer with keyboard and LCD.

These are "out-there" projects for after I get my feet wet. What starter projects would everyone recommend for someone getting started? I thought I'd start and perhaps make my mistakes with the 08M before moving up. Suggestions?

Jeff

 

[hippy]

Hi Jeff, and welcome. I've been looking to do a SID interface but haven't found a cheap C64 to cannibalise yet, once you get to grips with the PICAXE it should be doable.

The first thing is to read the manuals. You don't have to understand them entirely the first time.

To start programming, although these may sound trivial, they will give you a good grounding to get going with, let you know that you've got everything working and are ready to do bigger things ...

1) Use SERTXD to send a "Hello World" back to the Programming Editor Terminal Emulator. Make it print on a new line each time.

2) Use SOUND and TUNE to make a Piezo Sounder make noises. That made me go "wow" anyway

3) Turn a LED on and off and make it flash. Use HIGH and LOW, then use TOGGLE. Then use 'LET pins ='.

4) Try some maths and print the results using SERTXD. Try printing the squares of the numbers 1 to 20 using only byte variables ( LET b1=b0*b0 ), then replace the byte variable 'b1' which stores the result with a word variable 'w1' and see it work properly. Understand why.

At that point, I guess you'll be hooked and confident enough to think up your own programs to experiment and learn with. And the manuals will make a lot more sense.

Good choice to get an 08M and 18X. I'd start with the 08M because if anything goes wrong and ends in tears you've only lost a chip which is inexpensive.

Edited by - hippy on 04/04/2006 16:53:21

 

[manuka]

Hi Jeff! Glad you've stumbled upon us, as it's been a challenge alerting you Stamp guys in the US to Picaxe power. Endless DIY 08M ideas can be explored via the simple approach shown=&gt; www.picaxe.orcon.net.nz/bread08.jpg <A href='http://www.picaxe.orcon.net.nz/bread08.jpg ' Target=_Blank>External Web Link</a>. Stan in NZ

 

[jledger]

Made the mistake of mentioning this chip to my friend (who happens to be the pastor of my church) who immediately asked if one of my first projects could be a replacement Quiz machine for our quiz team. They have this really ancient box (made sometime in the 70's) that is used for the teens. The replacement cost is somewhere around $300+.
The unit works like this... there are 4 seat switches connected to a box with 4 lights, a reset switch, and a timer switch. When the &quot;Quizmaster&quot; asks a question, he hits the timer switch. The first person to standup (remove themselves from the switch) lights the light on the box. If no one moves, the buzzer sounds, and the question is lost. This sounds like a perfect project for one of the PICAXE chips, maybe the 18X I have coming. Has anyone done any projects like this in the past?

Jeff

 

[womai]

Hi,

this is perfectly doable with the Picaxe. The number of inputs (4 for each player + 1 for reset) and outputs (4 for each lamp + 1 for the buzzer) required means the 18X is probably a better fit. Note that the analog (ADC) pins can just as well be used as additional digital inputs if you compare the ADC value to a threshold somewhere in the middle of the range. Second, if you need to drive anything larger than a LED you will need to add some driver to avoid overloading (and destroying) the Picaxe outputs. For not-to-large loads a darlington driver is a good choice. Larger than that, and power MOSFETS (or relays, but being mechanical they wear out) are needed. To amplify the buzzer sound so you can hook up a real loudspeaker, I'd use an inexpensive integrated audio amplifier chip. And why stick with buzzer sounds - why not make it a short jingle melody? Lots of room to expand... but even then definitely cheaper (and definitely more fun) than the $300 replacement box!

Wolfgang

P.S.: As for those &quot;US guys&quot; needing to get hooked to the Picaxe - I sit in California (but then again, I am from Austria

 

[flyingnunrt]

And later on you can add an LCD an keep track of the scores etc.

Edited by - flyingnunrt on 04/04/2006 23:47:16

 

[jledger]

*** Newbie Questions ***

I hope no one mines a few of these while I come up to speed. Got my kit in the mail yesterday, and have a couple questions...

First of all, Do I need to Erase &amp; Run everytime I rewrite the software to the chip, or would a simple &quot;Run&quot; overwrite the chip correctly in one pass?

2nd, The kit I recieved had a sample program, flashing 1 LED without a 330ohm resistor. I suspect it's because it's a 5V LED. I've added a couple of my own also (without resistors.) Are the resistors intended to protect the LED's themselves from overvoltage, or the PICAXE from overload?

BTW, Kuddo's to Peter Anderson for providing a fantastic breadboard kit, ready to use with some basic information in the package. I honestly expected a blank breadboard with a bag of electronic parts, instead it was out-of-the-box ready to play with simple regulated power supply built in as well. Very Nice!

Jeff

 

[hippy]

1) Just click &quot;Run&quot;, the download program overwrites the existing one then automatically runs, no need to erase first.

2) I don't know about 5V LED's, but if you are using normal ones you do need a resistor, 270R/330R upwards ( I usually use 1K8 ). If you leave out the resistor the LED will draw too much current out of the PICAXE, then the smoke escapes, then the most fun you can have with it is pulling its legs off.