On Wed, Aug 6, 2014 at 1:19 PM, Miguel Garcia gacuest@gmail.com wrote:
A basic sketch of the block diagram: http://oi57.tinypic.com/16aeffb.jpg
ok great.
so, things that are missing from the diagram:
* digital GPIO IC connects its IRQ-OUT to EINT0-IN on EOMA68 * one GPIO IC IN pin is needed for MicroSD "detect" * EOMA68 PWM out goes to LCD PWM * digital GPIO IC OUT pin needed for power-up of LCD * accelerometer IRQ goes to digital GPIO IC IN * digital GPIO IC IN pin connects to IRQ-OUT of AXP209 * digital GPIO IC IN pin connects to Headphone-detect (in case you want to alter volume on headphone-out)
so you probably want at least 2 16-pin Digital GPIO ICs because that's quite a lot of GPIO. you have two EINTs so you can at least chain all the EINT IRQs together.
if you start using USB (with an STM32F) then you will need 2 USB hubs (or drop the USB Flash Drive idea)
if you use UART (with an STM32F) i would be concerned about the speed / latency of the control protocol communicating data.
honestly i think you are better off with discrete GPIO and ADC ICs (SPI for preference, I2C otherwise).
l.