Community Question

CAP1188 - 8-KEY CAPACITIVE TOUCH SENSOR BREAKOUT - I2C OR SPI

Hey EZ-Robot. Is this something you would consider adding to your new sensors? I know those building InMoov with V4's would love it. I am sure others would like it also.
Troy
Commented April 2015
That device on post #1 looks good if you need a lot of input but don't want to tie up 8 ADC ports. If you're not bound by those constraints then KISS and do what DJ suggests and it will be more simple to implement.
thetechguru
Commented April 2015
DJ (or someone who knows more electronics than me), can you explain in a little more detail how you hook this up? What does it mean to let the wire float? Are you just connecting the bare wire to the ADC signal port and nothing else? Where would the capacitor go and what do you mean by "small" (range of acceptable specs)?

Thinking about something like this on the ends of a gripper so if it grabs a person (or the cat) it wouldn't squeeze too hard.

Alan
Richard R
Commented April 2015
@Alan... pin "float" means that at any given time the signal pin on a port can be high or low... It floats so to speak back and forth.... You could use a pull-up resistor to keep the pin high or a pull-down resistor to keep the pin low... Both would stop the pin from "floating"... The analog port basically just measures resistance (or a voltage level between 0V - 5V)... So if you were to say touch one finger to the analog signal pin and then with another finger touch the ground on the same port you should see the value change in the analog control window... Actually haven't tried it, but that's what I am assuming will happen, anyway...

***EDIT*** Just tried it and it does drop the analog value.... interestingly enough, but not surprising the harder you squeeze the two wires between your fingers the lower the analog value goes...

So you could use this as a crude method to determine if your claw is crabbing something conductive like a cat or a human hand or even something way more conductive like metal....
Doombot
Commented April 2015
@Richard R
I have used copper tape as a flex sensor it works pretty well...just need to apply the values and script it. A lot of trial and error.
Now that the topic is up why only 8 adc ports? Since I barely use servos at all it would be nice to have more analogs for all kinds of sensors...I actually use all of them.... ;)
thetechguru
Commented April 2015
Thanks @Richard R and @Doombot. I will play with this.

Alan
Question
AvatarCochranRobotics
Asked on Tuesday, April 14, 2015