PiFace Control and Display - Review

Table of contents

RoadTest: PiFace Control and Display

Author: reidmere

Creation date:

Evaluation Type: Independent Products

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: Simple display module, using PicAxe for handling 3.3v peripherals.

What were the biggest problems encountered?: Lack of support. Tried through email and facebook, but never got a solid answer for why it couldn't find the package. Problem was not the suggested answers, but the fact I ran an updated 3rd-party Raspbian (Moebius) that didn't support many things. Only work around I found was to use a Raspbian distro and remove packages.

Detailed Review:

I've been experimenting with making robots recently, the main reason for me getting a Raspi.

 

After getting it connected, it worked quite well. But without PLENTY of Amps, it will look washed out.

In fact, the documentation with it was inaccurate and left much to be desired:

The instructions claim incorrect specs of the Raspi: It has a 1A fuse.

Since the instructions claim that the PiFace takes 200mA,

leaving a model A with 650-900mA, or 850-1400mA for a model B.

However, with the 1A fuse, you may not have enough power to START your RPi.

 

If you have trouble booting with this, remove anything plugged into the RPi,

add a PiRack with another power source on the 5v pin,

or replace the on board fuse, if you feel comfortable.
I personally used a home-made PiRack like interface.

 

 

This is definitely a good item, but seems to lack some key features I was looking for.
None of the outputs for this seem to have 5v out, and it took me some digging to find this out.
Also, I feel it should be made clear: Without a Pi-Rack and ribbon cable, there's no apparent way to use with 5v apps.
Considering I had to power a 5v chip, running 4 cables to it, plus run an electric source to the 5v power pin on the Rpi,

as to make sure I could power it with my other peripherals, I had to find a work around.

Sadly, either the PiFace wasn't released yet, or nobody told me.

 

This is definitely nice as a dev-kit, but there's still much that lacks documentations for novices.
There is little I believe they could improve on this, except proper documentation first and foremost.

 

I can see this being extremely useful int he future for controlling relays by software or button press,

not having to purchase or mount any extra equipment. I wanted to test the infrared,
but my only TV remote broke, leaving me helpless there.

Anonymous
  • The 16x02 Displays have a power requirement around 2-3 ma and probably say another 20ma for the back light and probably no more than another 20 or so for the I/O chip and a LED or two so I'd think we are safe in the 50ish ma range ..Not actually measured it though.

     

    That very small pot is indeed the contrast control going to pin 3 on the display

  • Hi Christian,

     

    If it looks washed out, it may be that the contrast adjustment needs fine-tuning (there is a small trimmer resistor), With no additional hardware connected, the board likely consumes far less than 200mA, but I'm not sure. A lot will depend on what is being driven from the board.

    Often 5V logic devices can be controlled with 3.3V logic outputs (usually the logic high threshold falls within the input range of the 5V device). 5V outputs from external hardware will need to be level converted however. For documentation, this link should help, has drawn up the schematic for this board.