LCD id help  - Page 1
Forum section: electronics / beginners

author: hneve
author_rank: Regular Contributor
timestamp: March 07, 2016, 06:58:25 am
content: Hello, I have been given a lcd module and cant find any info out there about it.Have tried looking through pictures and descriptions but i fall short on anything matching.Hope someone here have seen this bugger and can point me in the direction of how to use it.attached are front and back images.Added: picture without black schroud as requested.

author: LordHexahedron
author_rank: Contributor
timestamp: March 07, 2016, 07:05:00 am
content: if you bent those metal tabs so the screen comes off the board that might help (I do find that method of fastening something quite curious, I've never seen it used in real life)

author: bktemp
author_rank: Super Contributor
timestamp: March 07, 2016, 07:24:41 am
content: There seem to be only a very few segments on the LCD. Typical 2x16 LCDs need 16+5*16 = 96 wires. Here I can see only 10 on one side. My guss is, it only shows some Icons or some other custom Icons.Finding the correct data sequence the LCD might need to switch on can be difficult if you do not have the device where the display came from.

author: hneve
author_rank: Regular Contributor
timestamp: March 07, 2016, 07:28:35 am
content: It was taken from a LG air conditioner indoor part, thats all i know.When i removed the black housing i touched something and it looks like its a numbers lcd as i saw a few bars of something looking like 7-segment.

author: hneve
author_rank: Regular Contributor
timestamp: March 07, 2016, 07:32:53 am
content: there was 1 more rubber strip but i let that be stuck to the lcd. it was seated where you see the 10 pads.

author: Simon
author_rank: Unknown
timestamp: March 07, 2016, 07:34:29 am
content: It is probably using the hitachi standard LCD controller that I can never rememdber the number of or a clone of it. I think the pinouts tend to be standard.

author: bktemp
author_rank: Super Contributor
timestamp: March 07, 2016, 07:40:32 am
content: Quote from: blueskull on March 07, 2016, 07:29:53 amAll the wires from the driver ic on the back of the pcb must go to the LCD on the front, so through the PCB. That's why there are vias everywhere on most LCDs (random picture from google image search):http://www.piccircuit.com/shop/167-thickbox/2x16-lcd-display-yellow-backlight.jpgHere there are almost no vias on the PCB and almost no traces next to the ic. So it does not look like any standard display, more like a highly customized solution.There are some SPI and I2C versions of 44780 controllers (Sitronix has some nice ICs). But this looks more like some simple Holtek or other more simple shift register based LCD controller.

author: Simon
author_rank: Unknown
timestamp: March 07, 2016, 08:03:16 am
content: Quote from: blueskull on March 07, 2016, 07:36:20 amIt's very possible to use 4 pins, they have 4 and 8 bit comunication. Nothing to do with SPI

author: Simon
author_rank: Unknown
timestamp: March 07, 2016, 12:36:14 pm
content: well there are nine wires, yes you have things like contrast, if you don't connect to it you probably won't see anything even if you communicate correctly with it.

author: Ian.M
author_rank: Super Contributor
timestamp: March 07, 2016, 01:29:19 pm
content: The big clue is the pads for a 32.768KHz crystal. Its probably a 4 digit clock/timer display. Assuming the 12 vias round the COB go to the display, and it uses 4:1 multiplexing, that would fit well with 4 digits, a colon between them and up to 3 annunciators.

author: bktemp
author_rank: Super Contributor
timestamp: March 07, 2016, 01:29:45 pm
content: Finding the pinout is difficult, because we know absolut nothing: Even if we have the pinout we still do not know what data to send to make the LCD tun on.Hence one of the most important rule when salvaging such parts: Measure signals before taking everything apart.My guess is some Holtek IC like HT1621. Why? Because there is a unpopulated 32768Hz crystal on the PCB. HT1621 supports external 32768Hz crystals, but also has an internal RC osc.Let's assume it is a HT1621 then the pinout would be:1: Backlight (?)2: Vcc3: VLCD4: GND5: DATA6: WR\7: RD\8: CS\9: BacklightThere are 4 vias on the left side of the ic (for COM1-4) and 6 on the right side (for segments).The HT1621 can do 32x4 segments, but only 6x4 seems to be used.Since everything fits perfectly, I would give it a try assuming it is a HT1621.

author: hneve
author_rank: Regular Contributor
timestamp: March 07, 2016, 06:22:08 pm
content: I got it working thanks to bktemp , thank you ,, only it was some kind of special display with funny icons on it ,, no numers ,, lolz1 experience richer ,, thanks guys