Finally got my PICAXE kit

[shaneshane1]

just though i would let all that helped me out over the last few weeks know that i finally got my picaxe kit yesterday, and am picking up on it really fast.

No matter what you chose shaneshane1 I'm sure you'll have fun and learn something to boot. Hope you share your projects with us.

well i have posted something on youtube for you all to see, its nothing special, but its a start for me at the moment, i first tested to see if a LED lit on an output, and once i got that to work, i jumped straigh into the 7 segment display, which you will see soon on youtube.

iv uploaded the video to youtube but its taking a while to show up, so ill give the link when it has come through, Thanks!!!

 

[Mike - K8LH]

congratulations and we all hope you enjoy this wonderful and exciting new adventure...

Mike

 

[futz]

just though i would let all that helped me out over the last few weeks know that i finally got my picaxe kit yesterday, and am picking up on it really fast.

i jumped straight into the 7 segment display, which you will see soon on youtube.

Hey that's great! Post that link. 7-segs are fun to tinker with, but hard to make look good in video.

 

[shaneshane1]

well here it is the video has finally shown up

https://www.youtube.com/watch?v=dHMdNAOcJLI

 

[futz]

well here it is the video has finally shown up

https://www.youtube.com/watch?v=dHMdNAOcJLI

Cool! Now do 2 or 4 displays.

 

[shaneshane1]

Cool! Now do 2 or 4 displays.

??? off the same chip ???

 

[justDIY]

??? off the same chip ???

yep! tis called multiplexing - you share all the connections of the first display, except for the common cathode/anode of each display goes to its own pin on the axe (probably best with a transistor)

 

[atferrari]

Just started

You see now? Always, there is something else possible!

It will be like that for the rest of your life!

 

[shaneshane1]

iv been trying to work out how to use the chip away from the board, from what i can see i need to connect serial in/out to something, but what???

iv read something about a 10k and 22k used for normal operation?

does anyone know how to run this chip away from the board.

 

[Leftyretro]

iv been trying to work out how to use the chip away from the board, from what i can see i need to connect serial in/out to something, but what???

iv read something about a 10k and 22k used for normal operation?

does anyone know how to run this chip away from the board.

The help manuals in the Picaxe program editor has all the information needed to show how to set up a picaxe chip in a stand-alone circuit.

The first manual (getting started I think) has pin out diagrams for all the different model Picaxe chips, so find your chip type. Some chips require an external resonator or crystal, others use only internal RC oscillators, others can use either and switch under program control. The 10K and 22K resistors make up the external parts required to have the Picaxe talk to the PC program editor via a PC comm cable, you don't need to use the serial data function if your standalone circuit doesn't require any outside communications to anything else. This is only needed if you want to be able to download to the chip in it's standalone circuit, desirable but optional. You could do the downloading in your development board and then remove the picaxe chip to your standalone circuit, it will auto start on power up.


Lefty

 

[shaneshane1]

iv sorry I've worked it out, i just needed a 10k pulldown on my serial in, and now it works fine without the board, i thought there was more to it than that, but there wasn't.

 

[shaneshane1]

Cool! Now do 2 or 4 displays.

off the same chip

yep! tis called multiplexing - you share all the connections of the first display, except for the common cathode/anode of each display goes to its own pin on the axe (probably best with a transistor)

I've been trying to work it out, but i dont get it

 

[futz]

off the same chip

Yup. You need 7 pins to switch the segments (8 if you want DP) of all the digits, and also one pin per digit to power the common cathode or anode. Since the CC or CA handle the current from all segments you should use a transistor on each digit to switch the current.

The digits get switched on and off in sequence, very quickly so only one is on at a time. Very quickly so the eye is fooled into thinking they're all on at once. It's called persistence of vision. Switch them too slowly and you get flicker. It's how movies work. They're just a series of still pics, but flash through them at 24-30 frames/second (or better) and it becomes motion.

Your code has to do some stuff to make sure the correct segments are lit as each digit gets enabled. Timer interrupts are your friend here. A timer counts up on its own, allowing your code to continue as normal. When the timer rolls over (this happens many times a second) an interrupt service routine is called that does the stuff to display the next digit.

I know it's not the most coherent explanation, but I'm gradually editing it till it gets clearer.

Once you learn multiplexing you can do stuff like **broken link removed**. That 3x3x3 cube takes 12 pins to control. It's like 3 digits of 9 segments each, only not arranged in numeral shape, and with the digits stacked on top of each other instead of laid out side by side . Took me a few evenings to get the code written, debugged and fine tuned.

Whether a Picaxe has the speed to do proper multiplexing I just don't know. I suspect it might, but possibly not. If not, you'd have to use outboard chip(s) to do it. **broken link removed** kit uses the very cheap and easy to use CD4022 chip to do its multiplexing rather than have the processor handle it. Takes only two MCU pins to control it. You could pick up one or two of those and play with em. Download the Dragonfly assembly instructions for a nice clear schematic of how to do multiple 7-segs. If you don't use the 4022, just imagine those wires from the transistor bases connecting to your Picaxe instead of to the 4022 chip. Nothing else changes.

The Dragonfly uses common cathode displays. If you're using common anode displays you'll have to use different transistors (PNP) and wire to 5V instead of ground.

 

[bananasiong]

Hi,
Something like this..

When you switch the 7-segment displays fast, the flickering will not be noticeable.

 

[futz]

Hi,
Something like this..

When you switch the 7-segment displays fast, the flickering will not be noticeable.

Excellent Bananasiong! An animation is worth a thousand words.

 

[bananasiong]

A picture is worth a thousand words, an animation is worth a thousand pictures

I did this for the presentation of my last project.

 

[alhoop]

iv been trying to work out how to use the chip away from the board, from what i can see i need to connect serial in/out to something, but what???

iv read something about a 10k and 22k used for normal operation?

does anyone know how to run this chip away from the board.

From the "Getting Started Manual":
'The 10k/22k resistors must be included for reliable operation.
DO NOT leave the serial in pin floating as THE PROGRAM WILL NOT RUN!'

The serin pin must not be left floating, I always tie it to ground through a 20k-30k resistor or just leave the 10k,22k programming combination hooked up in the operational circuit.

Al