After searching the forum with the search terms "piface" and "getting started" I want to start from the ground up. I have the document "Piface digital 2 getting started.pdf" from http://www.piface.org.uk/assets/docs/Pi ... tarted.pdf but would like further knowledge.
I have the Piface which I have not used and after checking the pinouts I can use the first 26 pins of the RPiWZ's GPIO.
I have seen the document and it does not answer all my questions, technical, programmatic. Please bear with me.
* My RPiWZ does has a power supply of 1000mA. HOWEVER if I connect the PiFace, how much extra current do I need, especially if I used all the open collector outputs and switched both relays on.
* please clarify this on open collector outputs:
(i) What is the maximum collector current?
(ii) Does open collector mean that I can use a higher voltage say 24Vdc if I have a load that requires 24Vdc and transistor is fully saturated? Reference page 6 piface documentWhat is the maximum voltage that can be applied to the output of the transistor?
(iii) Similarly what is the maximum current of these open collector transistors?
(iv) Snubber diodes, page 9 pdf document. Why does it say to disconnect the snubber diodes if for example I want to drive more relays through the open collector outputs and I need a snubber diode when the relay is switched on and it generates back emf? Use 'your own' diodes in this case?
* Please clarify this. There seems to be two kinds of logic levels, 5V and 3.3V. From my elementary knowledge of Ohm's law, the example resistor/led circuit has a 220ohm resister suggesting that 5V is used. Reference page 5 piface document. So the 3.3V level is only for serial communication?
*Please clarify this. In the Piface document there was nothing about configuration files on bootup as there is for networking. Is there meant to be a configuration file.
*sudo apt-get install python3-pifacedigitalio, page 11 of the pdf for installing the piface package. What is the minimum version of python? And can you still use something like pip install python30-pifacedigitalio ?
* Outputs, and inputs, page 3 of the pdf document and the software. Given that there are 8 inputs and 8 outputs, has anybody been able to put extra logic circuitry at the inputs and outputs and program the piface such that one can have 2^8 = 256 inputs and outputs.
Thank you
Anthony of Sydney NSW