Some devices sending input data seem not like pull down resistors. I should make changes to my 20pin and 28pin board settings to connect for example digital temperature sensor. With outputs i can connect devices straight to picaxe pins. Put i suppose this won't help regarding the inputs, pulldowns can't be "jumped over"?. However there are these holes next to pic on my 20 board.What are those holes for?
So my question is: have you found clever ways to alter board designs to connect devices needing for example pullup resistor instead of pulldown?
Do you have experiences of internal pullup? Could i just leave board without pulldown and use this as default setting?
I was already familiar with
I was already familiar with that wonderful piece of information, and i read it carefully again… but couldn’t actually find any tips considering altering the basic setup. Aren’t all those inputs of 28 pulled down as default? And 28 hasn’t those little next to pic “input holes” that i’am wondering about.
There is indeed a pull-down
There is indeed a pull-down resistor on each digital input. There are no pull-up or pull-down resistors on the outputs. The resistors are in a single in line package (SIP), which looks like a black ceramic strip. It is between the IC socket for the Picaxe-28 and the digital inputs.
Just in case you haven’t seen it (I’m not assuming anything), check the datasheet for the Axe020 28-Pin Project Board.
I don’t believe there is any way to bypass the pull-down resistors, unless you want to desolder the resistor SIP. Note: I DO NOT RECOMMEND THAT YOU DESOLDER THE RESISTOR SIP.
The Picaxe Manual 3 has guidance on interface circuits for the Picaxe. What device or devices have you noticed a problem with? It is possible that you have mis-diagnosed the problem as having to do with the pull-down resistors. If you let us know the specific device and problem you are having, we might be able to help better.
I just thought of something.
I just thought of something. If you REALLY need to get an input port with no pull-down resistor, you can reconfigure one or more analog inputs as digital inputs. Picaxe Manual 1 Appendix E explains how to do this for a Picaxe-28X.
Since the analog pins do not have a pull-down or pull-up resistor, this should allow you to do what you are looking for.
