4-wire Touch Screen interface? Read a touchscreen, and emulate one too.
Has anyone used a prop to interface with a 4 wire touchscreen? (I don't know the specifics)
Ideally I would like to be able to read the touchscreen and also emulate the signal to forward on to the existing OEM hardware.
I would like to put a propeller in as a 'carputer' in my '06 Acura TSX. I found a link where a guy 'patched' in a PC with the Acura nav system, and hooked up a 4-pole relay to tap into the 4-wire touchscreen which is in the nav system. The 4-wire interface was then connected to the PC side via a USB touchscreen controller.
He has a toggle switch to switch between the OEM and PC touchscreen controller.
What I would like to do is have the prop be able to read the 4-wire from the screen, and then generate the equivalent signal for the OEM side.
I don't want pass thru, but want to have the prop control some functions on the OEM, so it needs to emulate a person touching the screen.
Thanks
Seth
Ideally I would like to be able to read the touchscreen and also emulate the signal to forward on to the existing OEM hardware.
I would like to put a propeller in as a 'carputer' in my '06 Acura TSX. I found a link where a guy 'patched' in a PC with the Acura nav system, and hooked up a 4-pole relay to tap into the 4-wire touchscreen which is in the nav system. The 4-wire interface was then connected to the PC side via a USB touchscreen controller.
He has a toggle switch to switch between the OEM and PC touchscreen controller.
What I would like to do is have the prop be able to read the 4-wire from the screen, and then generate the equivalent signal for the OEM side.
I don't want pass thru, but want to have the prop control some functions on the OEM, so it needs to emulate a person touching the screen.
Thanks
Seth
Comments
I am including a example to program the ezLCD-004 using the propeller a photo of the actual screen.
Seth
if it's a resistive screen the datasheet for this www.national.com/pf/LM/LM8300.html part should give some idea how they're normally read.
Bingo! google found this focus.ti.com/lit/an/slyt209a/slyt209a.pdf pdf file that gives an overview of resistive touch screens.
and another one www.hampshiretouch.com/doc/appnotes/AN103%20How%20an%20Analog%20Resistive%20Touch%20Screen%20Works.pdf
I bet a couple of digital potentiometers could emulate a resistive screen really well. connect the two wipers together and then the ends go to the car.
I bet the Prop's counters running as Sigma-Delta ADCs could be modified to read a resistive touch screen. (hm... the prop counter ADCs will load the circuit, this will make reading the position more complex.)
have funish
marty
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Paul Baker
Propeller Applications Engineer
Parallax, Inc.