Has anybody tried to programme the LCD's that are on the multimeter , I think they use graphic lcd's as they can draw on themselves images of ohm etc.is there any way? or anyone worked with them?
Usually LCD's in Multimeters are customer devices. They are "dumb" devices that require a special LCD controller to work. Usually LCD's in Multimeters are multiplexed 1:4 so you need a controller that supports this.
A little reading here: http://www.ampdisplay.com/resources_lcd_drivers.html
// Per.
arent many multimeters ,, just single line LCD,, more like a connection of LEDs - two wires = 1 segment ?
woody_unreal:
arent many multimeters ,, just single line LCD,, more like a connection of LEDs - two wires = 1 segment ?
No. LCD's don't work that way.
Look at the number of electrical connections on the LCD glass itself. If it has 31 display segments (7 segment display, some colons, comma etc) it's probably a static display, that is - a pin for every single segment and a common backplane connection. The displays in Multimeters, Graphic or not, have generally very few connections, because the LCD glass is multiplexed.
Both types of LCD displays require a special controller. Powering the LCD display from an DC signal from a micro yields a display that fades out quickly and breaks, due to chemical detoriation.
Some more reading: http://ww1.microchip.com/downloads/en/appnotes/00658a.pdf
// Per.