[Arm-netbook] IC for analog and digital buttons (EOMA-68)

Luke Kenneth Casson Leighton lkcl at lkcl.net
Wed Aug 6 13:18:26 BST 2014

On Wed, Aug 6, 2014 at 1:19 PM, Miguel Garcia <gacuest at 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).


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