hie , i do have a big 20 pin lcd which is commonly used in digital multimeters . can you please help with pin out ,i want to connect it to a microcontroller
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If it is from a Multimeter it is probably just a display without a controller.
There are PIC devices with LCD controlers built in but you would need custom wiring and software to suit the Display panel.
I may be wrong but I doubt that any of the GCBASIC LCD Drivers will work as they are normally used to talk to the LCD Controller and not drive the raw LCD.
Last edit: Chris Roper 2019-09-11
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I disassembled the digital multimeter ,its just a raw LCD without a controller . It seems like a mono-chromatic graphic LCD. How can i make my PIC18F4520 /452 communicate with a raw graphic LCD
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I think it's faster and easier to buy a new display with a controller. LCD displays are cheap and you can choose the size and color tone you want. Can use OLED display, it is even more beautiful.
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I am with the guys. But a cheap on and then it will be easier.
There are chip like the 16f1937 that with generate the LCD signals but unless you have a detailed datasheet it will be very very hard. And, none of the standard libraries will work. It will be a huge task. Unless of course... someone else has already done this on web.
Anyone else want to add anything?
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It can be done, but as has been said it is tricky. The only advantage is the low current draw.
The picture is of a 8 digit 7-segment display which I took out of a calculator (it draws about 10 uA).
The problems:
1. The Zebra strip connector - you have to keep this under compression to maintain contact and you have to find some way of connection this to your controller.
2. Finding the connections - you can "inject" some small voltage into each of the conacts to see which segment comes on.
These are not wired like LED displays as there are a number of segments associated with a base planes. So one of these base planes could be controlling segments across several digits.
3. You need several voltage levels to make sure that sgments that should be off are kept off.
4. The voltage needs to be reversed regularly to prevent polarization.
Now some PIC chips will do some of this for you. I used a 16F887 (which does not have a LCD driver) and created just one intermediate voltage (it works in this case, but other LCDs you will have residual "glowing" of off segments without more voltage levels). I think it works because mine only has 3 base planes.
Thanks guys for your suggestions . i designed a digital infrared speedometer but my lcd is 2x16 and is small. I want a large LCD thats why i am trying to use one from a DMM. Currently i can't buy any GLCD
Last edit: getsi 2019-09-16
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I can't currently see any for sale, but some time ago I found, in some old machines that we were scrapping, a couple of 16x2 LCD modules labelled as CCM-1624CSL. The displays came home with me rather than in the skip. These are standard 16x2 character LCD modules but have a character size of (almost) 10mm x 5mm. In operation they (appear) to follow the usual LCD 1602 type display instruction set. I used one in my Grid Frequency Meter so I could read them from across the room. [Searching for "ccm-1624csl lcd" did turn some up for sale, at $140.00. Ouch! I'll sell you my spare for half that...] If you look on Elektor-Labs for Grid Frequency Meter there should be some pictures of them working. The frequency 'cursors' are underlined on the 1624 display, on the 1602 display the cursors are not underlined.
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hie , i do have a big 20 pin lcd which is commonly used in digital multimeters . can you please help with pin out ,i want to connect it to a microcontroller
Hi,
Bit of odd question - there are 1000's of example on Google.
But,, what chipset? Which microcontroller?
PIC18F4520 controller
try LCD_IO 4. should work. Have a look in the help.
See attachment. The layout to the LCD is similar for your chip.
Last edit: Anobium 2019-09-11
If it is from a Multimeter it is probably just a display without a controller.
There are PIC devices with LCD controlers built in but you would need custom wiring and software to suit the Display panel.
I may be wrong but I doubt that any of the GCBASIC LCD Drivers will work as they are normally used to talk to the LCD Controller and not drive the raw LCD.
Last edit: Chris Roper 2019-09-11
I disassembled the digital multimeter ,its just a raw LCD without a controller . It seems like a mono-chromatic graphic LCD. How can i make my PIC18F4520 /452 communicate with a raw graphic LCD
Before that.... can you take some photos. Front and Back please. I want to see the PCB and the CoB.
I think it's faster and easier to buy a new display with a controller. LCD displays are cheap and you can choose the size and color tone you want. Can use OLED display, it is even more beautiful.
anobium sorry for the delay i was failing to attach the photos . The LCD has more than 25 pins
Last edit: getsi 2019-09-12
I am with the guys. But a cheap on and then it will be easier.
There are chip like the 16f1937 that with generate the LCD signals but unless you have a detailed datasheet it will be very very hard. And, none of the standard libraries will work. It will be a huge task. Unless of course... someone else has already done this on web.
Anyone else want to add anything?
It can be done, but as has been said it is tricky. The only advantage is the low current draw.
The picture is of a 8 digit 7-segment display which I took out of a calculator (it draws about 10 uA).
The problems:
1. The Zebra strip connector - you have to keep this under compression to maintain contact and you have to find some way of connection this to your controller.
2. Finding the connections - you can "inject" some small voltage into each of the conacts to see which segment comes on.
These are not wired like LED displays as there are a number of segments associated with a base planes. So one of these base planes could be controlling segments across several digits.
3. You need several voltage levels to make sure that sgments that should be off are kept off.
4. The voltage needs to be reversed regularly to prevent polarization.
Now some PIC chips will do some of this for you. I used a 16F887 (which does not have a LCD driver) and created just one intermediate voltage (it works in this case, but other LCDs you will have residual "glowing" of off segments without more voltage levels). I think it works because mine only has 3 base planes.
Thanks guys for your suggestions . i designed a digital infrared speedometer but my lcd is 2x16 and is small. I want a large LCD thats why i am trying to use one from a DMM. Currently i can't buy any GLCD
Last edit: getsi 2019-09-16
I can't currently see any for sale, but some time ago I found, in some old machines that we were scrapping, a couple of 16x2 LCD modules labelled as CCM-1624CSL. The displays came home with me rather than in the skip. These are standard 16x2 character LCD modules but have a character size of (almost) 10mm x 5mm. In operation they (appear) to follow the usual LCD 1602 type display instruction set. I used one in my Grid Frequency Meter so I could read them from across the room. [Searching for "ccm-1624csl lcd" did turn some up for sale, at $140.00. Ouch! I'll sell you my spare for half that...] If you look on Elektor-Labs for Grid Frequency Meter there should be some pictures of them working. The frequency 'cursors' are underlined on the 1624 display, on the 1602 display the cursors are not underlined.