Before stating work on the xMT224 touch chip,

Before stating work on the xMT224 touch chip, I thought I’d post the current status of the Synaptics chip:

Great work - this is exactly the kind of thing I am after; a 4.3" HDMI screen with capacitive touch, instead of mounting some cape to the BBB.

Are these able to be purchased?

@Michael_Riksman they are not available right now, but a major distributor has expressed interest in buying the first batch, so hopefully they will be available for sale in a couple of months.

put me down for 2.

looking at the project; incredible stuff. would love to have the ability to do that kind of thing. had to make up a board for it as well?

@Michael_Riksman Ok, I’ll reserve two for you : ) The boards are “home-made”, Rev A2 is coming in tomorrow, so I am pretty excited about that!

so you do those schematics and like an EAGLE thingy. And then get them made up? Who do you use? And do they do the SMD soldering as well?

Looking at the schematics; you send the I2C to an ATmega and convert to USB?

Literally staring at this stuff with my mouth open…

For Prototyping, I use Seeed studio, they accept gerber files, which is industry standard. They do SMD soldering with a minimum batch of 100, but for prototyping I solder myself.
Yes, Rev A2 uses an Atmega 32U4 and that has both usb, i2c for the touch, a soft i2c for the LCD and pwm for controlling the backlight. It has to enumerate as two USB devices, one HID for the touch and one CDC or something for the other stuff.

hmmm, never tried SMD soldering :confused:
did you end up using the display you talked about back in March;
That has the 24 bit color connector…? What is the purpose of using a DVI controller then?

480x272? That is old school, man, I’m doing 480x800 on these babies! The DVI connector for converting from HDMI to parallel RGB.

boom I want 5.
so the parallel 24 bits come from the display in to the TFP401APZP, which converts this to TMDS/DVI?
love the ‘cleanliness’ of it. HDMI and USB giving capacitive touch and backlight controls.
why hasn’t this been done before? or has it, and my googling skills are terrible?

do u have the code that goes on the ATMEGA32U4-AU available? I’d like to take a look; I spent a lot of time on the ATmega chips before coming across to the BBB

It’s not written yet, but it will be available in a few days if everything goes according to plan!

haha good luck!

how is it done now? direct to I2C? does the BBB use it to do any initialisation? or does the TP401 do all the work?

The TFP401 does not need any initialization, but the LCD screen does. It has a 9-bit SPI interface that I bit-bang with some init code. The Touch screen is handled directly from the BBB. As you can see in the picture above there are four wires going to the touch part of the screen.