Project Feasability / Part Selection

Hi all,

I am looking for some guidance here.
I have had experience with RPi and other general microcontrollers but to date have had nil exposure to Ardunio and am struggling a bit with staggering amount of options and limited documentation on compatibility.

The project began in looking at is a low cost mechanism for wirelessly controlling toggle switches over my home network.
What I came up with as potentially the most cost effective solution was to get some Arduino (Thinking Uno R3) boards, tied with NRF24L01+ modules at the switches (GPIOs connected to reed relays etc) and a “master unit” (Arduino board TBA) with the same wireless module that would be connected to the LAN and listen for requests. Requests received would pass through a logic layer and be fired off to the correct switch via the module to toggle the respective GPIO.

From what I have read this in itself would be fine, though I couldn’t get much in the way of pin configurations for the wireless modules being interfaced to the Uno. Thinking a little deeper into this, came across some very low cost Touch LCD panels on eBay (Eg: http://bit.ly/1gTBo0G) that would be cool to interface at the switch as well for dual control as to remote wireless or local touch.

Where I come completely unstuck;

  • Is there any issue connecting an Uno, NRF24L01+ and Touch LCD panel (as linked) at the same time? Or do they require some of the same pins making this impossible on the Uno?
  • What would some of your recommendations be in relation to hardware to use? Are there better options? (Keep low cost in mind)

Appreciate any assistance that can be provided.

If cost or size is an issue, don’t use a UNO. There are numerous clones available at a fraction of the size and cost.

I haven’t used them myself, but the Ciseco RFu clones look like a small inexpensive clone with integral radio transceivers which might be useful for this project. Any of the common clones would work with the nRF24 modules, though. You could even use an XBee, if you don’t mind spending a little more.

PeterH: If cost or size is an issue, don't use a UNO. There are numerous clones available at a fraction of the size and cost.

Agreed, I have used NRF24L01+ with Nano 3 and Pro Micro. You can get Pro Micro clones on eBay from China for less than £3, as long as you can wait. I found the quality to be OK. And NRF24L01+ for around £2.

NRF modules communicate to the Arduino over the SPI bus. This consists of 3 lines, MISO, MOSI & SCK, which are fixed pins on the Arduino, plus 2 more pins, EN and CSN, you can use any 2 Arduino digital outputs for them.

Many colour LCD screen modules also use the SPI bus for both writing to the screen and reading touch feedback, so can share the same MISO, MOSI & SCK Arduino outputs. They will also need some kind of enable lines, those can't be shared other devices on the SPI bus. The screen you linked to does not seem to use SPI, but does seem to need a lot of outputs, you may run out. This screen for example seems to be able to use SPI for both screen and touch, so might be easiest to wire up to the Arduino and NRF module.

Paul

Thanks guys. Appreciate the feedback.

Looks like a Nano clone may be the way to go. There seems to be a great deal of information about using the NRF24L01+ modules with these.

Took me a while to figure out the SPI pinout from the specs of the LCD Paul linked, but seems to be the go to. Have ordered a couple for testing. Thanks again for the input!