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INT070ATFT-TS Set-up

I have an INT070ATFT-TS which I plan on using with a pic32 usb starter kit II (on an I/O expansion board) connected together through an interface board.

I just tested the INT with the interface board without the mcu stuff attached. I think I was expecting to see a white noise screen after the auto-initialisation. Instead nothing happened. I checked the voltage levels on the INT's pins and found the power input pins seemed to be correct, but I also found some of the other pins including some of the data pins to be held high to ~3.2V. I've checked my interface board when not connected to the INT and this does not happen which leaves me to conclude the INT is driving these pins high. I'm not sure if this should happen or not.

With regards to the reset pin I've read it should be held high during auto-initialisation but I've also read the mcu should set this to an input. Wouldn't setting this pin to an input keep it in a low state? Could the fact that when I connected the INT my interface board the reset pin was not connected and so would be in a low state cause the blank screen?

Would be very appreciative if anybody could shed any light on this.

Replies

dtechsupport's picture
dtechsupport
November 26, 2013

If you have no interface pins connected (reset, data pins, etc), the device should indeed come up with white noise after auto initialization. Please make sure you're applying the appropriate voltages, including the 5v to pin 38.
Regarding reset, yes, you should tri-state the reset as an input during the auto-initialization time to leave it floating, as the on-board Atmel chip will need to control the reset pin.

Guest's picture
Guest
November 27, 2013

Using a multimetre to check the pin voltages this is what I got;
1. ~0v
2. ~3.3v
3. ~1.2v
4. ~3.3v
5 - 6. ~0v
7 ~3.3v
8. ~2.5v
9-12. ~0v
13-17. ~3.3v
18. ~0v
19-26. ~3.3v
27-37. ~0v
38. ~5.0v
39-40. ~0v
This is with the board powered but not connected to a mcu so all other pins should be floating.
Using a scope I measured the reset pin from startup goes high for about 16ms, then low for about 160ms then high again where it settles at. Does this sound right?

dtechsupport's picture
dtechsupport
November 27, 2013

That appears to be correct. Yes, you should see the reset pin go low and high during the auto-initialization. At the end of that time, can you tell if the backlight on? As a reference, please see the attached schematic for interfacing to the INT 7".

Guest's picture
Guest
November 27, 2013

I can't see anything on the screen. I imagine even if there was no noise to display the screen would appear lighter with the backlight on. The overall power consumption seems too low for the backlight to be on too. The regulators powering the INT 7" are themselves being supplied by a bench power supply at the moment. I'm clocking a little less than a third of a watt in power consumption in total for the whole int 7". Doesn't the backlight consume more than a watt?
Just to check, the through hole headers either side of the screen, h2 and h3; h2 has pins 1:20 with 1 at the top yes? Leaving h3 with pins 21:40 with 21 at the top?
Thanks for the files. I came across the second one on this forum before and am using the same pin to pin connections from the mcu to the INT 7".

dtechsupport's picture
dtechsupport
November 30, 2013

Thats correct, the backlight should consume more than a watt. Thats also correct regarding the pinout of H2 and H3.
I would make sure that the backlight supply is not somehow being current-limited. Also, have you made any modifications to the jumpers on the INT070ATFT-TS?

Guest's picture
Guest
November 30, 2013

No modifications have been made to the jumpers. Do any need to be made?
The backlight is being powered by a 5v switching dc-dc regulator rated up to 1A. It's possible the input capacitor to the regulator may have a bad connection (solder) to the circuit and so effectively removing the capacitor functionally. This could cause problems for the regulator but I would of thought if something was wrong it would show up on the output voltage to the INT70. On a scope not only is the voltage level correct but there is little ripple.

dtechsupport's picture
dtechsupport
November 30, 2013

No, the jumpers should be fine as they were shipped.

The only thing I can think at this point is that the backlight or logic is simply not getting enough power, but as you said you should see something. It appears that the auto-initialization is happening correctly since you're able to see the control lines changing at power-up. I'm not sure I have any other ideas. Perhaps try connecting the INT directly to a controlled power supply?

Alternatively, Displaytech sells Microchip development and demonstration boards for the INT 7" if that would be helpful to you.