I kind of assumed that both pin 15 & 16 serve the same purpose across the two displays. Ground and power respectively. Maybe I’m wrong. Do you think it’s possible to use the Midas display? Or am I just asking for too much?guy.k2 wrote: ↑Mar 17, 2019 7:02 amI don't think pin 15 on the Midas is the same function as on the BuyDisplay board.
15 and 16 are backlight anode and cathode to power backlight for the Buydisplay,
Pin 15 is a negative voltage output on the Midas going to an off-module contrast control.
Midas backlight is powered by Pin 16 (cathode) but rather than pin 15, backlight cathode goes to vdd via a resistor,
I just tried what you mentioned above there is no text on the Midas display when all pins but 15/16 are hooked up. Tried the same with the buydisplay lcd and I can see text but obviously no backlight was on.guy.k2 wrote: ↑Mar 17, 2019 4:01 pmI think you can eventually get it working, but need to change how pin 15 is connected to match the circuit diagram in the Midas spec sheet. They don't specify the resistance between it and Vdd.
My approach would be to check if data and and display will even operate would be to connect everything EXCEPT pins 15 and 16.
That should let the rest of the display operate. You won't have any backlight, but can illuminate it from the front to see if proper text is appearing. It will be faint, but detectable.
If you get text display, you know the data lines and LCD controller are working.
I would attach pin 16 directly like the other pins.
Smoke test. If that passes...
Pin 15 (Vee), I would route to a variable resistor wired as in their diagram for external contrast control...
Screen Shot 2019-03-17 at 9.04.12 AM.jpg
Oh. I thought you were using one of the post smoke units with a replaced cap.All the components I used to do the test without the backlight have been brand new components. Both LCD’s and the LCD controller are brand new
That may be it. Constrat pot turned all the way up and I’m reading 5v from pin 3, turned halfway down its about 2.7v.guy.k2 wrote: ↑Mar 17, 2019 7:41 pmOh. I thought you were using one of the post smoke units with a replaced cap.All the components I used to do the test without the backlight have been brand new components. Both LCD’s and the LCD controller are brand new
So with new components, that's not encouraging in terms of verifying compatibility. I wonder if the controller is feeding correct contrast control voltage for Midas LCD operation. What do you measure on pin 3 (V0)?
Misas spec says VDD-V0 must be between 6.2 and 6.8 volts.
Whereas the Buydisplay uses V0 contrast control at 4.5 to 5.1 volts
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