3 1/2 Lcd

[Ioannis]

Hi!

Did anyone made an 3 1/2 numeric LCD work with PIC mcu's?

I would like to use it in a electronic thermostat for hotel rooms. It would be more ergonomical to use this LCD that alphanumeric kind.

Thanks,
Ioannis

[NavMicroSystems]

Ioannis,

the easiest way will be to use a LCD controller like

MICROCHIP AY0438

or

MAXIM ICM7211M

regards

Ralph

[Melanie]

Done exactly this for a Digistat application... used a 3 digit 7-segment LED module from Kingbright and multiplexed the display directly from the PIC needing just three external Resistors... the display cost under $1 in volume. The two LED module (needing only two external Resistors) is even cheaper at under 50 cents in volume. Check with your local Kingbright distributor.

[Ingvar]

Hi Ioannis,

It can be done, infact it's quite simple. All you need to do is to output 1:s to all the segments you want "lit" and 0 to the B.P, then you invert all of it and output it again. Keep doing this at a rate of 32Hz to keep flickering at a minimum(or higher for none).

I used a few 74HC595:s as I/O expanders as this approach will reqire lots of outputs. 3 1/2 digit LCD:s usually require around 30 pins or so. The hc595:s cost "peanuts" in bigger volumes. You could ofcourse use a PIC with lots of pins if that's more to your liking.

I have a six digit display driven this way, it's been running 24/7 for exactly a year now(today infact) without any problems atalll.

/Ingvar

[actionplus]

Do you what the 7 digit LCD that you used? I am trying to look for something about 5x2 and 5x1. I have seen a few without the Hitachi controller, and I don't even know how to begin.

I know I can buy these bare LCD's, then get the Hitachi controller. But where will I go from there?

Is there anyway of using a 16F877A and an LCD without the controller? Is this possible with PICBasic Pro?

[NavMicroSystems]

There are many ways to do the job.

If you can afford to use 10 (or more) Pins on the PIC to drive the display directly
and if your software allows to Multiplex the digits without flickering
(means there are no other time consuming tasks) the "direct drive" might be an option.

Using an intelligent LCD Controller would save a lot of I/O pins,
Codespace and execution time. You could probably go for a "smaller" pic and get a controller chip for the savings.

I have already mentioned different LCDs on another thread
(i.e. one with embedded I2C controller)

another option would be to use a Graphics LCD with embedded controller.
(i.e. Display for NOKIA GSM Mobiles)
They are available as "spare parts" and are about $5 - $7

[Ingvar]

Actionplus,

We are discussing bare LCD panels with 7 segment digits. The kind you'll find on cheap(batteryoperated) clocks, thermometers and such. It sounds like you're interested in alphanumeric LCDdisplays, those i always buy prefab. The smallest i've seen is 8 digits with 1 or 2 lines.

/Ingvar

[Ioannis]

Thanks to all!

I guess Melanie's idea is the most cost efficient. I'll check the cost of these LED's, though LCD 'burn' almost nothing (I'll need about 250 of these x 3 digits x 30mA = 22.5A max! The Hotel manager might get some ideas about this!!!)

Ioannis

[actionplus]

Yes, you are right. I am talking about the bare lcd glass with the controller in it already. Those come as small as 4 digit which I would like to work with.

Doesn't seem to see anyone work on it before in here. Cause for my application, I want it as small as possible. Like voltage reading. I just want to show 5.00

Let me know if anyone has seen anything like that done with PICBasic Pro via parallel connection.

Thanks

[Melanie]

I drive the complete module (including PIC, relays etc) from a 1.5VA transformer.... x 250 units = running cost of a couple of light bulbs. What budget hotel is this guy running? You'll be telling me next that they only serve hot food in the afternoons when the sun has sufficiently heated up the patio slabs round the back of the kitchen...

[NavMicroSystems]

Originally posted by Melanie
I You'll be telling me next that they only serve hot food in the afternoons when the sun has sufficiently heated up the patio slabs round the back of the kitchen...

Mel,

it's a solar powered hotel ;-)

[Ioannis]

Come on Kids, I was kidding! Of course Melanie the 22A is OK for the hotel, just thought of the number comparing wit the LCD's micro Amps.

I am sure the LED's would be also more impressive for the customer.

Ioannis

[fratello]

Hi!

Did anyone made an 3 1/2 numeric LCD work with PIC mcu's?

News ? I am interested about this too...

[bogdan]

the easy way to control a dumb lcd is to use pic16f91x, pic16f19xx, .....

[fratello]

Example(s) ?! Please !!!

[bogdan]

my first project = a box for cigarettes (unfinished...like the others )
..in the meantime i quit smoking


lcd test forum.pdf
lcd test forum.zip

[Archangel]

..in the meantime i quit smoking

Good For YOU ! That is BETTER than finishing this project! Now you will have TIME to do projects, without cigarettes killing you first! I hope working on this project helped you quit.