Wow! what a busy couple of weeks, I've had a few extra days away from home that I wasn't expecting so updates have been a bit short on the ground, I decided to get straight on with things rather than blog intermittently.
The project is close to complete, most of the case is now finished, see pictures below. Gimo2 has had a few more wires surgically implanted onto an expansion port so gpio signals can be sent out.
The current point of focus is soldering up some proto board with the i/o expanders to make them a bit more permanent as part of this project then to fit everything into the case.
The communications connundrum...
Most microcontrollers come equipped with hardware communications ports namely serial, parallel, i2c and spi some with can etc... The limitations of Gizmo2 leave I2C and SPI as the only viable options for internal communication which is great, only.... microcontrollers usually only operate as master devices whereas this system would need them to function as slaves.
Having only 6 gpio, parallel is also ruled out. I need to find a way of transmitting data from Gizmo to a microcontroller. I'm considering implementing a 4 bit parallel interface with 4 gpio to act as the 4 bit wide data port and 1 gpio to act as a clock signal and the final gpio to operate as an acknowledge/ interrupt bit... all fun stuff!!
Once the electronics are out of the way, cobbling the software together should be easy enough. The system should be up and running by the end of the month still though I expect to be missing the bar graph displays and a few extra bits and bobs that are going to come with future updates.