PicAXE Newb serial connection question

[mad_sci_guy]

Hi everyone,

This is my first post, I'm a total newb to picaxes and I was wondering how to hardware connect my picaxe 28x to the TLC5940 The data sheet talks about SIn, Sout and Sclk ports... no idea what to do with the Sclk. I'm using this circuit to control a RGB led and I just need to figure out how to get it connected correctly so I can start playing around with the software .

Thanks guys/gals!

 

[manuka]

Start Simply !

???- surely an overkill for just a single RGB LED??? Even a 08M could initially handle this! The TLC5946, being a 16-Channel, 12-Bit PWM LED Driver with 6-Bit Dot Correction , IMHO is quite a heavy duty chip for gaining basic PICAXE insights! Have you explored basic HIGH, LOW, SERIN, PWM etc?

 

[mad_sci_guy]

I thought the picaxe could only pwm out on 2 channels? and the rgb led needs 3 channels? Correct me if I'm wrong or if theres an easier way to do it.

thanks

 

[manuka]

Duplicate posting

 

[manuka]

The 08M has a single background PWMOUT feature (Pin 2),but PWM is available on Pins 1,2,4.

Of course,aside from PWM, this may be delivered simply by turning each of the tri-colour LED lines fully on or off. Using it in this way you get color outputs: Red, Green, Blue, Magenta, Cyan and Yellow (& White with all 3 on) - without complex PWM control.

I'd said INITIALLY of course - RGB LED settings are so subjective- " Ah- exactly the greeny-blue I wanted to mirror the growth in the fridge"- that all manner of tweaking may be involved. Diffusing the output & maybe double speeding the 08M (to 8 MHz) may help improve the visual effect.

Check previous RGB Forum postings => http://www.picaxeforum.co.uk/showthread.php?t=5007

 

[mad_sci_guy]

???- I want to use complex pwm control so I can get a full range of colors. The attached link says you cant use the 08M, it says you need to use one for each channel or use a chip like the one i described above... I tried to write my own pwm software but the chip isn't fast enough to get proper results. (It flickers) Any help connecting to the chip i described ???

 

[womai]

Another possibility - use three 08M's, each controlling one color LED. Given the low price of the 08M, that's very feasible. One of them would be the master, telling the other two what to send out through PWM. Or if you like symmetry, use 4 08Ms, one being the master, driving the other three which are each connected to one color.

 

[mad_sci_guy]

The 08M is like $3.50 that would be $10.50 to control 1 LED! That is redic... Using the serial connection you can connect like a hundred leds individualy controled, and the picaxe 28x1 is only like $11. Can anyone suggest a way to connect this chip? or another chip, possibly an i2c pwm chip?

 

[manuka]

But have you quickly wired a tri-colour LED & tried ? How about clock doubling? It's fair to say PICAXEs slower execution times ( ~1 milliSec each) indeed may well mean flicker issues, but human persistence of vison (POV) usually ease this.

I don't have an RGB LED handy to try, but recall a commissioned 08M driven artwork here in NZ (undertaken by Andrew "Brightspark") that produced gorgeous shimmering hues emulating our paua shells.

 

[mad_sci_guy]

I've tried using a tri color led, it just doesn't work, the software pwm isn't good enough, and the pwmout command can only be used on 2 pins.

 

[manuka]

Fair enough on PWM flicker- did you double to 8MHz? Andrew informs his art work used PULSOUT (apparently inspired by a past "Hippy" Forum posting), so suggest you search/try this.

As mentioned earlier,colour effects are INCREDIBLY SUBJECTIVE & you are strongly advised to grab a PICAXE (maybe the cheap multiple output 14M/20M ?) & tinker with the diverse output commands to suit your needs. One man's meat is another's poison of course...