USB to GPIO module

I'm working on a project which involves having users press buttons on a webpage which the server needs to send onto a microcontroller in the form of a GPIO signal. The only ports available on the server are USB.

I have had a couple of thoughts:

1. Just use an Arduino board as the USB to GPIO interface.


2. Use a purpose-built module such as the http://numato.com/8-channel-usb-gpio-module (this is pretty much the only one turned up in a quick Google search.


3. Use something like what is described in this question. Drive LEDs from USB

Can anyone with experience in this area make a recommendation?

Answer

Perhaps the simplest solution to the stated requirement is the FTDI FT245R IC.

The key points of note in the context of the question are:

• Royalty-free USB drivers from FTDI for Windows, MacOS and Linux (MacOS support only for USB VCP mode)


• Complete USB device mode protocol handled on-chip without custom programming


• Complete USB hardware on-chip, including USB resistors


• 8 GPIOs available - will allow future expansion for inputs from the microcontroller too


• USB suspend / resume support, to switch device to low-power mode when not in use


• Integrated level converter and 5 V, 3.3 V, 2.8 V and 1.8 V totem-pole output, so it can talk to most standard microcontrollers


• No additional crystal or oscillator required, it's all integrated.


• Free sample implementation code for both computer and FT245R ends

In terms of time saved in implementation, and future requirement bloat, this is perhaps the fastest, simplest and cheapest 1-chip answer to the requirement. Price for individual units is around $4-5, and in the $2 range in volumes.