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Forum Index : Microcontroller and PC projects : Micromite LCD BackPack V2 Display Issue
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| loup Newbie  Joined: 01/07/2017 Location: AustraliaPosts: 20 |
Greetings, Hope someone can help. Newvbie here so have some patience please... I had a running LCD Backpack V2 with I think was v5.03.02 firmware. I updated to 5.04.08 and after setting the LCD to OPTION LCDPANEL ILI9341,L,2,23,6 the LCD washed out with almost full backlighting on. I set the PWM for the LCD to 10% and after running GUI TEST LCDPANEL, I could just make out a faint representation of the circles. I downgraded back to 5.03.02 and have the same issue with the LCD seemingly being washed out! Any help would be appreciated. My guess is that somehow the LCD has been flashed with something that it is causing it to always come up as washed out. Regards, Lou |
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| WhiteWizzard Guru  Joined: 05/04/2013 Location: United KingdomPosts: 2944 |
Welcome to the Forum Lou. Can I suggest you first type (at the Command Prompt) OPTION LIST This will show you what has been set. Just check that indeed you typed the LCDPANEL parameters correctly  If it shows as ILI9341,L,2,23,6 then I would recommend you re-flash the firmware. Of all the MM BackPacks I have assembled & tested I have never come across one that caused the LCD to fail. Do also check it is mounted correctly and that all pins are connected (i.e. one not bent out of place and hence Open Circuit). Let us know how you get on WW |
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| loup Newbie Joined: 01/07/2017 Location: AustraliaPosts: 20 |
Thanks for the prompt reply... OPTION LIST gives me this... OPTION LCDPANEL ILI9341, L, 2, 23, 6 I have re-flashed the firmware of the LCD BackPack several times and am now back to V5.03.02! Is there firmware to flash on the LCD module? Bit strange how it was working OK prior to flashing firmware to v5.04.08. I don't think it will be a hardware issue as all I did was to press the mode buttonl, but I will check joints and reseat the LCD nonetheless. Thanks, Lou |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2944 |
Nothing to 'flash' on the LCD. Did you re-flashing without the LCD module connected? Should not make a difference; but . . . . BEFORE you run GUI TEST LCDPANEL, type: PWM 2,1000,100 Report back after (if you can) WW |
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| loup Newbie Joined: 01/07/2017 Location: AustraliaPosts: 20 |
I re-flashed with the LCD connected. PWM 2,1000,100 still gives me the same washed out backlighting and I cannot see the GUI TEST LCDPANEL circles. I can only barely see the circles when I use PWM 2,100,10. Thanks again... Lou |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2944 |
Can I recommend that you disconnect the LCD; and then re-flash (with latest firmware). BEFORE you do this; just download the Firmware again; and unzip it if needed. I will stick around and await your feedback . . . . WW |
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| loup Newbie Joined: 01/07/2017 Location: AustraliaPosts: 20 |
Please don't wait. Had to dash off for an hour. Many thanks. Lou |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Interesting thread. I don't suppose you have another LCD you can try? I agree that the LCD should not be a problem, but for the purposes of experimentation, it is often useful to try another LCD and see if it is doing the same thing. If it is, something is wrong on the backpack PCB or firmware. If the replacement LCD works, then the first one has indeed become suspect. I have used a few of those SPI LCD's on things now, and I have never had one fail, so if your one really IS crook, it would be unusual and rather bad luck. I am watching this thread with interest to see what happens. Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2944 |
Hey Grogs, Do you know if you have ever flashed a BackPack with the LCD connected? I have only done so with the LCD dis-connected. Just curious . . . WW |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Yes, I have reflashed MMBASIC with the SPI LCD connected. Never a problem, other then you having to reissue the OPTION LCD command with the new firmware download, but that is normal. EDIT: NOT on a Backpack. I don't have any of those boards, but on my own projects where I have an SPI LCD connected. I don't see how the Backpack's pin choices could be a problem there, but who knows. Smoke makes things work. When the smoke gets out, it stops! |
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Azure Guru Joined: 09/11/2017 Location: AustraliaPosts: 446 |
I agree with others it is unusual for those displays to fail. Just adding some obvious things to check. If you are getting a faint image it would point more towards the backlight LED and its power than the LCD controller itself. Make sure all the solder joints are correct (no dry or cold joints), you may have upset a weak joint while doing the firmware upgrade. If you have a multimeter or scope check the voltage levels getting to the display panel power and backlight pins and work backwards from there. Can you confirm you have only used the PWM parts for the backlight brightness control and not fitted the potentiometer as well. How are you powering the backpack? |
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| Azure Guru Joined: 09/11/2017 Location: AustraliaPosts: 446 |
Yes I have flashed a LCD Backpack V2 with LCD connected multiple times with no problems. |
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| loup Newbie Joined: 01/07/2017 Location: AustraliaPosts: 20 |
Guys, I disconneted the LCD, un-sockected and re-soldered the backback, flashed the v5.03.02 firmware, re-connected the LCD and same issue. Soon as I connect the USB it comes up as full brightnes. Issuing a PWM 2,250,5 will make the GUI TEST Screen just visible if I angle the display. After every re-power of the backpack I must issue PWM 2,250,5 to stop the backlight from flooding the display. Suspect I have fried the LCD. Can smell a semiconductor smell if I leave it too long on full brightness. Could just be a heat buildup under the screen. PWM parts only used. No trimpot. Not sure what voltages are supposed to be. I will do some research and get back. Lou |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2944 |
Can you take a photo of the back of the TFT and post it here? There seem to be two main types of TFT module commonly available. It sounds like a component failure from what you describe - however; I do not believe this has been caused by just a software update. Maybe a closeup of the TFT will reveal a clue . . . |
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| loup Newbie Joined: 01/07/2017 Location: AustraliaPosts: 20 |
 Not sure if the LCD can be removed from the PCB? Sorry, my phone camera is ordinary. Lou |
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| Azure Guru Joined: 09/11/2017 Location: AustraliaPosts: 446 |
Seems like you have a fault in the LCD Backlight PWM drive circuitry. Default is the Backlight gets driven to full brightness. Display needs GND and 5V (VCC) to run LCD controller and panel. LCD Anode pin gets driven between 0 - 5V to produce off to full brightness on LCD backlight, controlled by PWM circuitry (2 mosfets (1 NPN/1 PNP) and 2 resistors which controlled by MM chip pin 26). Fault could happen if you accidently placed the 2 mosfets in the wrong position. On my unit the 2N7002 is labelled K72 CP and the DMP2215L is labelled 22P D7 is that helps at all. You could remove the DMP2215L and solder in the 100R 1/2W potentiometer to control the back light that way. That will tell you if the display or driver circuitry is the problem. |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
I have reprogrammed micromites with the LCD connected plenty of times. The PWM control seems to have some effect on the display brightness. If you can control the backlight from full on to full off with PWM commands, those components should be OK Because you can see the LCD test pattern at all, this suggests that the SPI commands are getting through OK so no problems with the backpack connections. That leaves the LCD panel itself or a connection between the panel and it's carrier board. The LCD can usually be pealed of it's carrier but I would only try that if I was going to junk the LCD anyway. Jim VK7JH MMedit |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2944 |
Ok - the transistor on the TFT (just above, and to the right, of the 16-pin Touch controller chip) is a possible cause of your issue. Does it get warm/hot if the LED backlight is on? |
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| loup Newbie Joined: 01/07/2017 Location: AustraliaPosts: 20 |
Guys, Thanks a lot for you assistance. I have placed an order for 2 LCDs from Silicon Chip. Will post results. Regards, Lou |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2944 |
To eliminate any other potential causes with a 'faulty' LCD module - please ensure you remove any SD card that may be in the socket. You probably do not have one inserted - but just checking . . . |
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