LCD display driving method/waveform type

Hello forum,

I got this display:

https://ace-systems.nl/Menu/Electronica/Displays/LC-Displays/LC1048.htm

and I would like to use it with PIC16F916.

Which waveform type should I use? Type-A or Type-B?

Thanks 8)

Regards,
Futterama

If you want to drive the display so that all the segments are available to use, you'll need to use 30 pins -- 1 pin for the backplane and 29 for the segments that you want to control (one for each segment). Any unused segments should be connected to the backplane signal. Another way (a better way, I think) is to use a chip like National Semi's MM5453 LCD display driver chip and let it do all the dirty work. The problem is, I don't know if they still make that chip.

*edit* Good news! National still makes that chip. Here's a link to the pdf datasheet: **broken link removed**. The link says MM5452, but the datasheet covers both the 5452 & 5453.
JB

jbeng, thanks for your reply, that chip looks like something I could use. But I think it is hard (expensive) to get in my country (Denmark). Actually they got is at farnell, but it's like $11 + $8 for shipping.

I guess the LCD signal type for this chip is Type-A.

And you are right, I probably need the PIC16F917 (40-pin) to use all segments if I use the PIC approach.

Futterama said:

jbeng, thanks for your reply, that chip looks like something I could use. But I think it is hard (expensive) to get in my country (Denmark). Actually they got is at farnell, but it's like $11 + $8 for shipping.

I guess the LCD signal type for this chip is Type-A.

And you are right, I probably need the PIC16F917 (40-pin) to use all segments if I use the PIC approach.

Click to expand...

Does the 16F917 include specific LCD support?, it's extremely important that the LCD is fed by accurate 50/50 AC signals, any DC offset in the drive will drastically shorten it's life. Commonly the LCD is driven by XOR gates, with one input from the data, and the other from an oscillator (guaranteeing the pure AC drive). Micro-controllers having LCD support include this type of system internally, as presumably does National's driver chip.

Nigel Goodwin said:

Does the 16F917 include specific LCD support?

Click to expand...

Yes Nigel, the PIC16F913/914/916/917 has internal LCD drivers and gives the option to use two different kind of waveforms:

PIC16F91X datasheet said:

The LCDs can be driven by two types of waveform:
Type-A and Type-B. In Type-A waveform, the phase
changes within each common type, whereas in Type-B
waveform, the phase changes on each frame
boundary. Thus, Type-A waveform maintains 0 VDC
over a single frame, whereas Type-B waveform takes
two frames.

Click to expand...

Futterama said:

Nigel Goodwin said:

Does the 16F917 include specific LCD support?

Click to expand...

Yes Nigel, the PIC16F913/914/916/917 has internal LCD drivers and gives the option to use two different kind of waveforms:

Click to expand...

That should be fine then, I tried to download the datasheet this morning, but all I got was a blank page?

Nigel Goodwin said:

That should be fine then, I tried to download the datasheet this morning, but all I got was a blank page?

Click to expand...

It should work, here is the direct link for the datasheet:

https://www.electro-tech-online.com/custompdfs/2006/01/41250E.pdf

Make sure you got a PDF reader installed (eg. Adobe Reader).

Futterama said:

Nigel Goodwin said:

That should be fine then, I tried to download the datasheet this morning, but all I got was a blank page?

Click to expand...

It should work, here is the direct link for the datasheet:

https://www.electro-tech-online.com/custompdfs/2006/01/41250E-1.pdf

Make sure you got a PDF reader installed (eg. Adobe Reader).

Click to expand...

I have, I downloaded the programming spec OK, then the datasheet just gave me a blank page?, perhaps a brief 'hiccup' at MicroChip?.

Nigel Goodwin said:

I have, I downloaded the programming spec OK, then the datasheet just gave me a blank page?, perhaps a brief 'hiccup' at MicroChip?.

Click to expand...

I just want to jump in here and say I had a similar problem with PDF documents when using Foxits free PDF viewer. However viewing with Adobe works fine. Not sure if this is your problem, but I thought I'd interject my $0.02.