My new 2*40 LCDs are not working… I get the black blocks on the upper line.
I ordered 4 CMC 240-02
Datasheet: http://www.microdevice.de/download/cmc240-02.pdf
They go at ebay for around 9 Euro.
The Core8 is working, PIC is running Mios.
LCD Interconnection application - everything ok
Different brand LCD connected with the same ribbon cable - works.
I checked the datasheet for the new LCDs, pinout is the same as with my old working LCD.
What could be the reason…?
i tested with another core module with no other modules connected.
Still no difference.
In the data sheet i read some little differences to my working lcd.
working lcd:
Data Setup Time: 60ns
E Rise/fall time: 25ns
non working lcd
Data Setup Time: 80ns
E Rise/Fall Time: 20ns
Everything else seems the same to me.
I only know my way around analog circuit design, so i am used to differences in this order not to couse any trouble.
Still, could this be the cause of my problem?
Thank you!
Did you try changing the contrast setting?
Many greets,
Peter
I think I had something similar when connecting the ribbon cable upside down once… 
Thank you for the hints.
Contrast is working, i can make the black blocks disapear by moving V0 from Vss towards Vdd.
The ribbon is fine and in the right direction. I have dil headers soldered to my lcds, so it is easy to swap and connect different lcds.
My old LCD is working fine with this exact ribbon, the 4 new ones i ordered are not working. So it´s also unlikley that i have a solder bridge on the dil-header.
WHen running the interconection test application i was measuring right at the lcd module.
It just doesn´t make sense at all to me…
Well, if another LCD is working it’s not your cable and not your core. If all 4 LCD’s are not working it’s doubtful that they are all broken. So I suspect either a different pinout (don’t trust the datasheet in this case! Maybe trace DIL pins to the controller IC?), or you try to run them in 4bit mode when they do not support that (a few OLED have been reported to only run in 8bit).
For the case that it helps:
non working lcd
Data Setup Time: 80ns
E Rise/Fall Time: 20ns
no problem, the PIC can’t toggle the pins in less than 100 nS
Best Regards, Thorsten.
Hm, so this is not the problem. I wasn´t expecting it would.
The application i am running is MB-LC, so the Display should be adressed in 8-Bit mode, right?
If the pinout is different, how can i trace it to the controller? Or differently put, how can i see what the controller is and how can i know what pinout it has?
Yes, MBLC accesses the LCD in 8bit mode.
Be careful with the pinout: very likely it’s identical to common LCDs, if you would try one “wrong” connection, you could fry the LCD!
Although users haven’t reported problems with the MIOS8 LCD driver in the last years, it can’t be excluded that your LCDs behave a bit different to the standard. Therefore it would be interesting, if the alternative CLCD driver causes a change: see http://www.ucapps.de/mios_download.html, search for “lcd7_clcd_v2a.zip”, just download the precompiled .hex to test it.
If it doesn’t work, power-off the core, wait for 3 seconds, power-on again to ensure that your LCD starts under reset conditions. Does this help?
Best Regards, Thorsten.
Hello Thorsten,
I didn´t have the chance to test this just until today. Unfortunately no luck. With the hex you linked i get the message “hello world” from my working LCD. The new ones show nothing. Not even the black row…
I did some testing with a second psu to generate a negative V0. The datasheet says Vdd-V0 is typically 5v but can be 12v max. If V0 is about 8v below Vdd a second row of black blocks appears.
I also noticed the lcd is in some way responding. During booting the core the blocks flash, also with midiio128 the blocks will disapear and reappear with some note on events.
Maybe i should move on…
V0 has only an effect on the contrast. If you already saw the black row after power-on, it won’t help to increase the voltage.
This case still puzzles me, because from the datasheet I would say that these are pretty good LCDs where no compatibility issues have to be expected. :-/
If you can’t find a way to get them working, and before you throw them away, just send me one or two LCDs so that I can test them at my side.
Best Regards, Thorsten.
I would be happy to send you a LCD, thank you very much! Just sent you a PM.