Input and Output problems on PICAXE18

Arthur C

New Member
I've built the Basic 18Pin Picaxe Download PCB from the PICAXE Website.

The PCB layout shows 5 Inputs and 8 Outputs.
If using a PTM switch as inputs to I simply put one in, or do I need a Pull up/down resistor for each switch?

Also, on the outputs, I can't seem to get a simple LED to work? (is this because the output current from Darlington Driver Chip is too great?).

Thanks in Advance!
 

BeanieBots

Moderator
Can't remember about the two digital inputs but the 3 analog inputs do NOT have pulldown resitors.
The darlington is 'open collector'. That means it can only sink current. Therefore you must connect your load between 5v and the darlington output. This gives a double inversion so the net result is that the command "High" will still have the same effect. ie. the load will come on.
When using LEDs, don't forget to include a series resistor or you won't be able to see the light through the smoke.
 

BeanieBots

Moderator
Yes, if you want to use them as digital inputs with a PTM switch. They don't have pulldowns fitted as standard because that would upset the value if/when they are used as analog inputs.
 
Top