[Arm-netbook] passthrough card stm32f072 firmware

[Luke Kenneth Casson Leighton]

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crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68


On Thu, Mar 16, 2017 at 3:40 PM, Albert ARIBAUD <albert.aribaud at free.fr> wrote:
> Hi Luke,
>
> Le Tue, 14 Mar 2017 07:32:17 +0000
> Luke Kenneth Casson Leighton <lkcl at lkcl.net> a écrit:
>
>> sorry albert just checked the schematics and also watterott's
>> HDMI_Display schematic - it's HDMI DDC that the STM32F072 needs to
>> emulate!  but looking at the watterott schematics that's just an
>> EEPROM (again).
>>
>> l.
>
> OK, I'm lost :) and not really familiar with the passthrough card so let
> me try to find my bearings back; just stop me when I'm wrong. The goal
> is that the passthrough card advertise on its HDMI connector's I2C the
> display capabilities of the microdesktop it is slotted into. Correct?
>
> So at the interface level, it should behave as an I2C slave EEPROM wrt
> DDC_SDA and DDC_SCL (that's I2C1 on the STM32) and as an I2C master
> wrt the EOM68 connector's I2C. Right?

 no, ignore the EOMA68 connector entirely - that has nothing to do with this.

 the pins are the ones i listed.  which is *NOT* the EOMA68 I2C pins.
it's two *SEPARATE* pins which is why it really should be done as
bit-banging.

> Now, what I am not sure about yet is whether there are any conversion
> to be made between the I2C data read from the microdesktop(s I2C and
> the data to be provided on the HDMI DCC IC2.

 nnnope!  i would have said.  it's very very simple.  just straight
"read EDID data from EEPROM then replay EDID data from EEPROM.".

 that's all that's needed.

l.