Hippy - need help with 08M

I've got a project where I need to use a 08M (for size)

I need the following

2 Servo lines
2 ADC's
1 Output

Is there any magic registry setting to use to get the above config. Every thing I can work out I am short one output.

Many thanks
Dave

There's no way I know of using one pin per function; Pin 3 (leg 4) is input-only and non-ADC by silicon design.

It may be possible to double-up on pins, using them for ADC and output but that would likely require additional components.

There may be a possibility of cutting a larger PICAXE down to a smaller size, creating a "10M2" or "12M2". I can't recall which chips have had 'leg reduction surgery' successfully performed on them or whether the resulting pin-out would be suitable.

Here's the thread on leg amputation ...

http://www.picaxeforum.co.uk/showthread.php?t=13811

And a 'more sensible' suggestion for using SMD on a carrier to fit a smaller DIL footprint ...

http://www.picaxeforum.co.uk/showthread.php?t=16154

Looking at the pin-outs; if you wanted to go the leg removal route it seems you have a couple of options, three when the 14M2 is released. All with the caveat that none have been tried.

The 14M2 would be ideal with the bottom two pairs of legs cut off.

The 18M2 could have the top pair and lower three pair removed, and if that hit the silicon die, top two and lower two pairs but you lose the re-programming ability after that. Actually the 18M2 could be reprogrammable if download Serial In were paralleled to another 18M2 but with the risk previously discussed that you wouldn't know if the decapitated 18M2 had been successfully programmed. For a one-off that may be acceptable.

Another option for the 14M2 would be to remove the upper and lower pairs. That would lose the 0V/+V pins, but could perhaps be mitigated by using parasitic power through input pins. I'd opt for taking the bottom pair off.

I'm not sure what the actual silicon die size is nor where it's placed in the package. It may actually be possible to be more brutal.

Or stack 2 PICAXE 08M on top of each other. Only solder the +5v and 0v pins from one chip to the other. Splay the legs of the top chip outwards and solder short pieces of wire so they reach the PCB. Just an idea.

Or use a PIC12F683 and program it in assembler or compiled Basic. That gives you full access to all I/O pins for a total of 5 I/Os and 1 input, and much faster execution (needed to implement two servo outputs in parallel, probably running on an interrupt in the background). Of course a "bit" more difficult to use than the Picaxe...

if your really good you could take an 18m2 and extract the die by removing all of the plastic and then making it into a super tiny smd, but it would be very difficult, also two smd 08ms could be used

I don't know about the two servos, but one output (P0), one ADC input(P4), and one photomos relay = two ADC inputs.
http://www.picaxeforum.co.uk/showpost.php?p=57534&postcount=2

ken

Thanks Hippy
The reason of size was that I was hoping to use on to the micro 08M boards in the circuit - akin to a 'reflex Action' board so not to take processing use away from other area's.

The system was for the auto-parallex function re adjusting the angles of the eyes to the distance sonar to help with depth perception work (one ADC and 2 Servo's0 and the other was to handle the IR night vision using a LDR and Mosfet (ADC and Out)

However (thinks) if I can do a fairly simple divider network with the LDR and the Input Pin 3 I only really need it to test if it is bright light or dark hence 1 or 0

Thanks - you've given me another alternative.

Dave