P8x32a quickstart po-p7, can i set up switches not touch switches?

garyg

HI
I have a quickstart board and want to set up normally open pushbuttons on PO-P7.
On the quickstart board, those are set to work with the touch switches.
I need to use PO-P7 with Normally Open pushbuttons remotely connected by wire.
Someplace, I saw descriptions concerning ignoring the touch switches, but the arrangement of the
new website documentation causes me to not find this answer.

Recently, Life got in the way.
I'm very close to get back to my my microcontroller projects.
I'm attempting to find my way back to setting up my quickstart board to work with
the Parallax 4 button remote.

Any clues as to where to find out about this would be greatly appreciated.

If anyone needs more info to help answer this question, please ask.

Thanks

Duane Degn

I generally don't worry about the touchpads when I use P0-P7. The 100K pull-down resistors generally just effect the pin states if the pins would otherwise be left floating.

My suggestion is to have you push button configured to be normally low with the button press connecting the pin to 3.3V. I'd use a 10K pull-down resistor to better insure the pins are normally low.

If you wanted to use normally high buttons with 10K pull-ups, the 100K pull-downs (with the 10K pull-ups) would drain your battery 0.03mA on each button. All four buttons would draw 0.12mA of current if you used normally high buttons instead of normally low buttons.

If you're leaving a power LED on the board, the buttons would likely draw much less current than the LED.

Again, if you used the normally low buttons, the extra 100K resistors wont make a difference in the way the buttons work and will not draw the 0.12mA just mentioned.

If you do want to use normally high buttons and you don't want to lose 0.12mA of current, you could remove one of the resistor arrays used to pull the touchpads low.

Edit: See correction by Andy below. (Thanks)

garyg

Thanks Duane
Do you know which document you are refering to when discussing the 100K pulldown resistors?
I need to develop a mental picture of how I'll be loading the quickstart inputs.
I should be able to find this info on my own, but my stack of printed threads is approaching 6" thick.
I have several hours invested in my revisit, but I not finding what I'm needing for my mental image of this.
When I start, I'll more than likely use your strategy of the 10K pulldown resistors.
This will prove my concept, but I'll need to modify the program when loading it to my PropMini.

Thanks
Garyg

Thanks

Ariba

The best source for infos is the QuikStart schematic here

As long as nobody touches the pads the 100k resistors do not have any connection on one side, so they just don't care. With pullups or pulldowns in the range of 3k..10k at the Prop pin for your switches, also a touch on the touchpads will not have any significant influence.

Andy

Duane Degn

Ariba wrote: »

As long as nobody touches the pads the 100k resistors do not have any connection on one side, so they just don't care.

You're right. I missed that. Thanks Andy.

@Garyg, As Andy points out you can pretty much ignore the 100k resistors.

The QuickStart schematic is also available in the Propeller Tool's help menu.

garyg

Thanks,
That's exactly the info I was looking for.
I'll now be able to refamilarize myself with the Quickstart and get something started once again.