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I am using Oriole 8x1 LCD Module - 08108-3SL/X. I interfaced this module with my pic18f458 and made it display "12345678", so its working.However, the back light is not ON and when I vary the contrast pin, It only affects the numbers being displayed on the LCD but not the brightness. So my question is:

1). Does this model of LCD module even have a back light feature? If so, then why isn't it working? - It has not been mentioned in the website anywhere. enter image description here

2). Does anybody know where can I find the LCD commands relevant to this module?. As there is no information regarding the LCD commands on oriole site. The image below is the datasheet for 16x2 LCD module, I used this one since there was no datasheet for the one I am using i.e. 8x1. enter image description here

To those, wondering how I interfaced this LCD module and made it work without knowing where to find the commands, I am using a code snippet that was being used in my previous company. But I do not know from where they got the LCD commands relevant to this module, as its not there in the official oriole website. The below shows the schematics of LCD + PIC connections. I have used PORT D for D0 to D7 of LCD. Port C0 for RS, C1 for R/W and C2 for EN. I believe rest are understood. The schematics I have provided is generic.

enter image description here enter image description here enter image description here enter image description here enter image description here

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Backlight on most character lcd displays are independent of the lcd. Typically, if included, has a backlight Anode and Cathode pins. There are many without backlights at all too. The pins/pad will be there, but the hardware for the backlight might not be populated. Most manufacturers use a standard pcb which they customize as needed.

Based on your generic pinout/wiring, and since you got it working with a code sample, it's a fairly safe bet that it uses the nearly universal HD44780 alpha-numeric dot-matrix character lcd driver compatible code set.

HD44780, KS0066U and SED1278 are mostly interchangeable.

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  • \$\begingroup\$ There are backlight +Vled and -Vled pins on this display. And I have connected +Vled to Vdd and -Vled to Gnd, but I do not know if these pins are applicable or functional for this particular 8x1 LCD module. I will compare these instruction sets with the ones in my code and cross check. \$\endgroup\$ – PsychedGuy Oct 23 '15 at 7:17
  • \$\begingroup\$ @PsychedGuy the pins being there doesn't mean the hardware for the backlight is there. The pins/pads are always there. If you add a non-blurry picture of the lcd front and back I might be able tell you if it is or not. \$\endgroup\$ – Passerby Oct 23 '15 at 7:25
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    \$\begingroup\$ A closeup side view would help a lot. The backlight is a separate rectangular light pipe under the panel itself. \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 23 '15 at 7:28
  • \$\begingroup\$ Have added the pictures. Please check it out. \$\endgroup\$ – PsychedGuy Oct 23 '15 at 7:53
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    \$\begingroup\$ Did the test and I contacted the oriole LCD manufactures for confirmation, and got to know that their 8x1 LCD modules do not come with back light. Hence shifted to using 16x2 LCD which works fine. Thanks for passing by to support. Good day! \$\endgroup\$ – PsychedGuy Nov 3 '15 at 1:15
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On the photo that shows the back of the PCB, at the left side there are an "A" and a "K". If there would be a backlight LED I would expect it to be soldered in the two (now unsoldered and empty !) pads right between the A and the K.

So my guess is that the backlight LED is simply not mounted ! What could also be is that this module uses a small lightbulb (but with a cylindrical shape) as the backlight. The trouble with these is (like with any lighbulb) that they burn through when the applied voltage is too high.

My solution would be: disconnect pins 15 and 16 from the connector so that the microcontroller board does not interfere. Then measure with a multimeter on ohms the resistance between the 2 soldering points for the LED. If you measure an open then there is no lightbulb or it has broken. I would then just try to solder a LED in the module.

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  • \$\begingroup\$ I measured the resistance between the two soldering points and it just did not show any values. I guess, like you said its open. However, I did not get what you meant by " I would then just try to solder a LED in the module" \$\endgroup\$ – PsychedGuy Oct 23 '15 at 11:50
  • \$\begingroup\$ The lightbulb may have also been burnt. For that I need to test it by using Passerby's advise. Will check on that too and get back. \$\endgroup\$ – PsychedGuy Oct 23 '15 at 11:53
  • \$\begingroup\$ Since it's open connection you could replace lightbulb or if possible place a LED instead of the lamp. I have no idea if that is possible, I would have to hold the module in my hand to see that. Maybe you need to remove some of the silver coloured foil that is on the light-guide, to make a hole so that the LED's light shines into the lightguide. The lightguide is the thing between the LCD and the PCB. \$\endgroup\$ – Bimpelrekkie Oct 23 '15 at 13:04

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