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By Marburg
#115242
I'm using a Color LCD shield as a breakout board to connect ye olde Nokia 6100 screen to a LeafLab Maple. Though they're both in "arduino" form factor, it's not quite straightforward, particularly given the well-documented problem that the STM32 can't generate 9-bit SPI -- but the UARTs can generate something very similar.

Thus far, I've got nothing on the screen. On cursory examination my "SPI" appears correct, though I'm sure I'm making all sorts of protocol errors with it which I'll fix with time and a bit of trolling the web -- my code is a mishmash of Jim Lynch's and a few others.

Thus far, the backlight appears to be off -- just black screen all the time. I'm driving the backlight boost converter with 5V raw USB, and only getting 4.75 V at the backlight.

So, now the noob questions. If the backlight is has insufficient power (like 4.75V), will I see anything at all on the screen, staring into the inky darkness? I'm looking forward to _not_ having to rig up a separate 5V supply for the backlight (yet), so I'd like to separate out the possibility of a backlight problem (I can't see my brilliant graphics because the backlight doesn't have enough power) from an interface problem (I can't see anything because I haven't initialized the display properly). If the backlight is on but the display uninitialized, is it apparent -- do I get a bright black/blue/white screen?

Simple questions, I know, but would save a lot of experimentation.

Thanks
By NEMX
#116382
Hi Marburg,

I'm glad you posted this, because I am having the same problem. I put Peter Davenport's most recent LCD library and example code on my Uno, but I get absolutely nothing. I really hope I find a solution soon.


-NEMX
By Blackfin
#116390
Be sure you're applying 5V to the backlight power (POWER.4) and 3.3V to the LCD logic (POWER.5) or the LCD may be damaged.

You should be seeing more like 7V from the backlight with a 5V input so double and triple check the voltage inputs. You will need the backlight functioning to actually see anything.

BTW, I'm using the 6100 on the LCD-08600 breakout (same basic circuit) and running the LCD backlight from 5V with no issues. As well, I'm using a CYpress PSoC CY8C29466 which is also incapable of doing 9-bit SPI. However, the LCD is fine with the MSB being banged out manually and then using the SPI to send the lower 8 bits.

You shouldn't have to get fancy with trying to make a UART look like an SPI: Just send bit 8 manually and bits 7..0 through a standard SPI.
By NEMX
#116392
I got it to work eventually, and all of the images in the example code came up looking fine. Now, however, after removing the power and reapplying it all I get is the blank blue screen.. no more images

[EDIT] Fixed, but now discovered issues when LCD is connected on top of the Ethernet shield.

@Marburg: After very meticulously wiring the LCD to my Uno based on the schematic I got mine to work. Did you check your connections?
By ottensmeyer
#127686
Hi NEMX - question for you - I bought a new LCD shield, which is displaying only a blank blue screen - can you recall how you were able to fix that state on your board? The connector seems to be seated properly, using Arduino UNO so the 5 and 3.3V pins should be correct. Do the empty pads at R5, 7, 9 and 11 need to be populated? Something else?

thanks for any pointers
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