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.


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!!!

__________________
If we were over 100 times the size we are now, then wouldn't what we already have be nanotechnology!!!

Mike, K8LH

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

Mike

futz

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

__________________
=========================
Futz's Microcontrollers & Robotics
=========================

shaneshane1

well here it is the video has finally shown up

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

__________________
If we were over 100 times the size we are now, then wouldn't what we already have be nanotechnology!!!

futz

Cool! Now do 2 or 4 displays.

__________________
=========================
Futz's Microcontrollers & Robotics
=========================

shaneshane1

??? off the same chip ???

__________________
If we were over 100 times the size we are now, then wouldn't what we already have be nanotechnology!!!

justDIY

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)

__________________
If you don't have a planet, what good are gold bars?

want to contact me directly? gmail gordonthree
check out my project website: http://projects.dimension-x.net
Favorite numbers:
09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

atferrari

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

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

__________________
Agustín Tomás
In theory, there is no difference between theory and practice. In practice, however, there is.

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.

__________________
If we were over 100 times the size we are now, then wouldn't what we already have be nanotechnology!!!

Leftyretro

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

__________________
Measurement changes behavior

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.

__________________
If we were over 100 times the size we are now, then wouldn't what we already have be nanotechnology!!!

shaneshane1

off the same chip


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

__________________
If we were over 100 times the size we are now, then wouldn't what we already have be nanotechnology!!!

futz

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 this (6.8MB). 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. Blueroom's Dragonfly 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.

__________________
=========================
Futz's Microcontrollers & Robotics
=========================

bananasiong

Hi,
Something like this..

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

Attached Images

Mul Fast.gif (3.3 KB, 64 views)

__________________
Superman returns..

futz

Excellent Bananasiong! An animation is worth a thousand words.

__________________
=========================
Futz's Microcontrollers & Robotics
=========================