This is the next step up, a similar concept to the 08Mx motherboard, but with a 14M2. Plenty of I/O capability on this little powerhouse. This chip also supports up to 4 channels of hardware PWM, meaning that you can completely control up to 4 channels with minimal processor overhead, all the way from 0% to 100% duty cycle.
Currently available is the novel ‘Binary Timer’ which uses 8 LEDs to indicate bits 0-7, a potentiometer, a piezo sounder, push-button and a further activity LED. The concept was originally derived from the many binary clocks that abound and with help from the excellent picaxe forum, this was the result. Time is set by selecting to total sum of minutes on the 8 LED display, then pressing start. As time progresses the activity LED flashes once per second and the binary display counts up every minute. When count time = set time the software plays whatever tune you have programmed into it, before looping around and allowing you to set the time again. By using padding resistors the minimum time is set as 1 (not 0, no point in timing 0 minutes!) and a similar resistor is used at the top end, simply to not absorb the sound energy which is also connected to the same pin. Maximum flexibility here, using I/O as both I and O! It works well, with time being set anywhere from1 minute minimum and 1+2+4+8+16+32+64+128 minutes maximum (255 minutes), a total of 4 1/4 hours. The basis of some interesting packaging solutions I’m sure. All I have so far is a laser cut box, but novel displays are entirely possible and appropriate.
Above, a pupils example….No, I’m not sure why he wanted the numbers that large either, but it works fine…
And my own version….. If less of the PCB was exposed (just the sounder and LEDs for instance) there would be quite some saving on materials as the time numbers and ‘Brand name’ could be moved inwards.
Time to make another one I suppose!. The Board and controls approximate to the size of a 3 or 4AA flat-pack battery box for instance p/n 18-2912 or18-2913 from Rapid Electronics. There is a video of one of these here: http://www.g4xat.co.uk/piggyaxe-what-is-it/piggyaxe-advanced-files/
The next application is simply a way of driving 8 LEDs from a potentiometer – nothing special there but some interesting patterns available. Simply rotate the potentiometer to light up more or less LEDs.
From the same Picaxe forum came a KITT scanner (1980’s car show) light, implemented in software so quite ambitious. A little bit of pin re-allocation, software trimming and by using the potentiometer, a variable speed KITT scanner. It’s fairly compact code so you could easily integrate the two pieces of software into one.
This chip has plenty of scope to do all sorts of stuff – lots of memory space, the PWM capability and a whole lot more.
Next up is a 12 volt 8 channel power driver with dual potentiometer inputs. The 12 volt decision was taken due to the popularity and flexibility of the wonderful LED strips so this daughter-board has a 78L05 and relevant capacitors which feeds the motherboard down below. If the motherboard is dedicated then you can leave off the battery snap connector but don’t leave off the diode as reverse polarity connection will destroy the regulator and so possibly the Picaxe below. The daughter board has two transistor outlines shown – one for e-line series capable of 1 amp each (but around 35p each), and one for TO92 capable of around 0.5 amps each (but much cheaper at 5 p each). Choose to suit your budget and application. The software as written drives 3 channels with full PWM (currently on 12 volt RGB LED tape) and the next 5 channels as a simple decimal progression, currently driving 5 lengths of 12 volt white LED tape. I did try a binary progression but it was irritating to set! I have included a push-button for set functions progression and it can write to memory the RGB values for reselection on power-up. If you need access to all four PWM channels, simply leave out a potentiometer and a pin and jumper the required signal into the relevant transistor driver.
This builds into a significant light source with only short lengths of LED tape. It looks like this…the top 5 tapes are all whites, the bottom one is the RGB.
Be carful when using your own wiring to these tapes – it really does need the support given by some heat shrink sleeving, otherwise the wires WILL pull off the PCB pads. Detials on how to do this are on the second PIGGYAXE page.
Of course the wide availability of Arduino clone stuff brings benefits to any micro-controller user and this is a good example of what can be had for a few pounds. A 8 channel changeover relay driver board with opto-isolation, 5 volt relays and LED indication, all for a wonderful £5.65 each ……delivered!! The relays are ‘active low’, i.e. ground the pin to activate the relay.
See http://www.ebay.co.uk/itm/New-5V-8-Channel-Relay-Module-Board-Arduino-PIC-AVR-MCU-DSP-ARM-Electronic-/170745298865?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item27c1367fb1 , buyer beware as usual on ebay.
It won’t take long to build an ‘adapter board’ to piggy-back it onto the Piggymiddle, just got to decide how (and what!!!) I want to control with it – the relays are ‘mains rated’.
Thoughts include remote aerial switching, anything involving a 1-2-4 or 1 of 8 switch selection capability such as ‘select-a-ratio’ balun switching system (amateur radio project), just for starters.