LCD Display

[karenhornby]

I need help please.
Has anyone got any circuits for an LCD display that DOESN'T need a pic or similar to program it?
What i want ideally is a 1 line LCD display that will display one of 3 WORDS, that are preset.
It only has to display 3 words, one being DIESEL, the others being VEG OIL and PURGE, 1 at a time which one depending on which is selected by a switch or similar

IF it helps, I've attached a circuit diagram of what it will be connected to, basically when solenoid 1 and 2 are on together, it would read "VEG OIL", when both solenoids are off it would read DIESEL, and when S1 is pressed ( only solenoid 2 is active) it would read "PURGE"
ANY ideas welcome, or any other suggestions

 

[Super_voip]

I suppose it could be done with an EPROM or diode matrix but the programmer for an EPROM will cost far more than any combo of PIC or 8051 including the programmer. A diode matrix will take up a lot of space but could be done.

 

[blueroomelectronics]

Why not just use indicator lights?

 

[karenhornby]

Velleman K8045 kit?

The reason I didn't want to use a pic is I've no idea how to program them, and probably dont have whats needed anyway.

What I'm thinking at the moment is the Velleman K8045 kit, if I can get hold of one

Anyone know anything about this one?

 

[karenhornby]

Why not just use indicator lights?

Already have indicator lights on the circuit, but I was hoping to make it easier to see and less confusing if anyone else was driving the car hence the LCD idea

 

[blueroomelectronics]

Low tech indicator lights are still used as they are generally much easier to read than an LCD display. Color also helps convey information.
The Velleman K8045 would appear to suit your application.

 

[Super_voip]

The velleman kit looks rather large, and it has a high difficulty rating. You already have the most expensive part of a PIC programmer, the PC. PIC programmers can be built very cheaply, the code can be done in Basic and the circuits take little space.

 

[blueroomelectronics]

Well I could mod an old prototype kit I made called Robin. I've got about 100 PCBs left. It's designed for a 2x16 LCD though but a 1x16 should fit, with backlight control. Four inputs could be programmed easy enough.
**broken link removed**

 

[kchriste]

You could use a laptop to control it. But this would be overkill:
https://www.electronics-lab.com/projects/pc/020/index.html
Now, if you used LED displays, you could easily do this with a simple diode matrix. The V wouldn't look that good on a seven segment display but you could use 14 segment alpha types:
https://www.globalspec.com/Featured...lphanumeric_display_China_led_display/49901/0
The most elegant solution is a microcontroller like a PIC connected to your LCD. Then you could dump the 555 timer and most of the other circuitry also....
As mentioned, you could use large indicator lights with the words DIESEL etc engraved on the bezel.

 

[Torben]

Already have indicator lights on the circuit, but I was hoping to make it easier to see and less confusing if anyone else was driving the car hence the LCD idea

Hi Karen,

I can't off the top of my head think of a simple LCD display which would be easier to read while driving than bright indicator lamps.

What lamps are you using at the moment? If they're well-driven auto indicators they should be plenty bright. If you want to make them easier to tell apart, I'd try labeling them (maybe put one behind an opaque material with a cutout of the word 'Diesel' or 'D' and the second behind a cutout of 'Veg oil' or 'V', and the last behind 'Purge' or 'P') and make the lamps different colours. Or just use one of those tape labelers. The big thing is that drivers will quickly associate the colours of the lamps with the status so a quick glance will do the trick.

Just a thought. Good luck with the project whatever you wind up doing--it sounds really cool.


Torben

 

[Shax]

To do what you need with a PIC will only take 30 or so lines of Proton Picbasic..
I just lashed up some quick and dirty (aka untested!!) code to show how simple it really is!!!

 

[House0Fwax]

Velleman K8045 kit, Anyone know anything about this one?

I have one. It was very easy to build and works very well.
If you are in the U.K. Maplin sell them ready made ( more expensive than the kit though )
However, you need to have a serial port, from things I've read on the net they don't work with USB adaptors.

Then have a look at Nigel's LCD routines ( Tutorial 3 ), adapt the code to suit your needs.
Job done.

 

[karenhornby]

Thanks everyone for the suggestions, maybe I should try and figure out this pic stuff.
What exactly would I need to make it work, ie program the pic and how many external components are needed with it and how would you interface it to a display etc?
Sorry for so many questions but I'm intruiged now, the idea of losing components like the 555 timer circuit and possibly even more seems good to me unless its pretty expensive to but the bits needed to program a pic and learn as i dont want to spend like £100 just on something I could buy already made for less than a 3rd of that ready done such as the velleman kits

Anyone know of a single or two line LCD display module? with blue backlight? or that you can change the backlight to a blue one?

By the way... Nigel's LCD routines? (turorial 3) where would i go looking for that?
And any ideas of a simple dummies guide to writing pic programs as the bit SHAX sent has got me interested, I was thinking it would take maybe thousands of lines of code to write something, but at the moment I know NOTHING whatsoever about programming pic chips.
Last thing... i do have an rs232 port on my computer, I wont have one without that even though its getting old, some things rely on rs232 still

 

[SPDCHK]

Thanks everyone for the suggestions, maybe I should try and figure out this pic stuff.
What exactly would I need to make it work, ie program the pic and how many external components are needed with it and how would you interface it to a display etc?
Sorry for so many questions but I'm intruiged now, the idea of losing components like the 555 timer circuit and possibly even more seems good to me unless its pretty expensive to but the bits needed to program a pic and learn as i dont want to spend like £100 just on something I could buy already made for less than a 3rd of that ready done such as the velleman kits

Anyone know of a single or two line LCD display module? with blue backlight? or that you can change the backlight to a blue one?

By the way... Nigel's LCD routines? (turorial 3) where would i go looking for that?
And any ideas of a simple dummies guide to writing pic programs as the bit SHAX sent has got me interested, I was thinking it would take maybe thousands of lines of code to write something, but at the moment I know NOTHING whatsoever about programming pic chips.
Last thing... i do have an rs232 port on my computer, I wont have one without that even though its getting old, some things rely on rs232 still

The full tutorial can be found here

 

[karenhornby]

Brain burnout

Its pretty heavy reading this time of night but it looks interesting, and IF I've got the basic idea right......

Is it possible to program a PIC to measure two temperatures via some sort of probe? and once a preset temp has been reached (possibly by setting an LM35dz circuit?) activate a circuit (or two) that would then operate relays? and display on the LCD display one of a number of messages depending on which output was active, while say the 2nd line of the display would display a 3rd temperature (to be measured also)

sorry for so many questions "again" but i'm finding this quite interesting and yearn for knowledge but not having a programmer yet, or a development kit im resigned to learning by reading for the moment

 

[Pommie]

Is it possible to program a PIC to measure two temperatures via some sort of probe? and once a preset temp has been reached (possibly by setting an LM35dz circuit?) activate a circuit (or two) that would then operate relays? and display on the LCD display one of a number of messages depending on which output was active, while say the 2nd line of the display would display a 3rd temperature (to be measured also)

Yes, a pic can do all of that and more. Do you have a link to a description of what the circuit does?

Mike.

 

[karenhornby]

If you refer to my first post it has a gif of a circuit that i did.
The basics of the circuit was taken from this page http://www.escol.com.my/Projects/Project-03(Thermostat-1)/Proj-03.html
which is basically a thermostat, that once the temp probe (lm35) has reached the preset temp it trips a relay.

My circuit follows on from that one, and using on using a single LM324 comparator instead of the original LM358, 2 complete temperature sensor circuits and a timer circuit based on a 555 chip that once activated latches a relay for a set period of time (ideally 65 seconds)

To do the design using a PIC, IF its possible i'd like as much done in the PIC itself and as few external components as possible.

I've decided on a 2 line display OR if its possible to make it work "this" **broken link removed**


What I'm hoping for in the end, is to have a device that will measure 2 temperatures (water and diesel) in my car, and once the water temp is 75ºC AND the diesel temp is 50ºC 2 relays will operate 2 relays in various configurations, and a timer/buzzer circuit depending on the values of the LM35DZ's

 

[Pommie]

Most of what you need is on the site of a member here . The spare pins on the pic in the diagram can be connected to switches, relays or more LM35s.

As for the LCD, some time ago I did a demo using such a display - clicky. The advert doesn't state which controller chip it uses but going by the price I'd guess it is the KS0108.

Have you done any programming?

Mike.

 

[blueroomelectronics]

Don't think I'd use the diode pairs, typically 1N914 diodes are sensitive to temperature and are unnecessary for the LM34 / LM35.

 

[karenhornby]

Thanks for all the help so far, its quite interesting reading and I'm very keep to try this out.

BILL what would you use instead of the 1n914's? which would you recommend the LZ35DZ or the DS18S20 temp sensors?

No I've not done any programming at all "yet" however hopefully I will soon.
would a development board be worth buying to "experiment" with?

I've been looking for a good one at a decent price and stumbled on this

https://www.mikroe.com/en/tools/easypic5/

anyone have any experience with this or anything similar?

I've still got to decide what programmer to get yet. IF I got that EasyPIC5 board would I need to buy a seperate programmer or would it program the PIC from the computer?



ANY thoughts on using 3 or 4 DS18S20 temperature sensors instead of the LM35DZ's?


Anyone any ideas how (IF) i can get an output to trigger at a set temperature and stay even if the temperature goes higher than the temp I want it to trigger at?

Temp sensors either LM35dz OR DS18S20 depending on which is easier to incorporate and get working

This may sound a stupid question to most of you, but is there a comparator in the pic's that can be used to compare 2 (temp inputs) and trigger different output pins and logic circuitry (AND OR gates etc) for example
(this is what I've got in my mind so far)

INPUT A0 (temp sensor) (set for 75ºC)
INPUT A1 (temp sensor) (set for 50ºC)
INPUT A2 (temp sensor) the LCD Display shows this actual temperature AND shows the word OUTSIDE TEMP (actual temp) ºC (LINE 3 of display)
INPUT A3 (temp sensor) the LCD Display shows this actual temperature AND shows the word INSIDE TEMP (actual temp) ºC (LINE 3 of display)
INPUT B1 +V (from ignition switch)
INPUT B2 +V (from battery)
INPUT B3 push to make non latching switch

OUTPUT A0 (normally LOW) to relay driver circuitry
OUTPUT A1 (normally LOW) to relay driver circuitry
OUTPUT B3 (normally LOW) Siren/buzzer circuitry
OUTPUT 4
OUTPUT 5
OUTPUT 6
OUTPUT 7




IF input A0 ≥ 75ºC AND input A1 ≤ 50ºC AND input B1 is HIGH OR input A0 ≤ 75ºC AND input A1 ≥ 50ºC AND input B1 is HIGH THEN outputs A0 and A1 and B3 stay LOW

AND the LCD display shows the word DIESEL


IF input A0 ≥ 75ºC AND input A1 ≥ 50ºC AND input B1 is HIGH THEN outputs A0 AND A1 go HIGH driving the circuitry needed afterwards needed to activate a relay on each line output)

AND the LCD display shows the word the word VEG-OIL

( IF I remember my maths equations for MANY years ago then ≥ means equals or greater than and ≥ means equals or less than)

IF input B3 goes high AND INPUTS A0, A1 and B1 are HIGH, THEN output A0 stays HIGH AND output A1 goes LOW AND a timer starts that counts for 65 seconds

AND the LCD display shows the word PURGING

IF TIMER = 0 (65 seconds reached) AND INPUT B1 is LOW THEN outputs A0 and A1 go LOW AND power to LCD module goes LOW
IF TIMER = 0 AND INPUTS A0, A1 and B1 are HIGH, THEN OUTPUTS A0 and A1 GO LOW, and the LCD display shows the words POWER OFF! DIESEL ONLY (on 1 or 2 lines)

IF input B1 goes low BUT INPUT B3 has NOT gone high THEN
outputs 1 and 2 go low (inactive turning OFF both relays) BUT output B3 goes HIGH (sounding a siren/buzzer)

AND a timer starts that counts to 65 seconds

AND the LCD display FLASHES the word WARNING (line 1) and shows the word NOT PURGED (line 2)

WHEN TIMER = 0 (65 seconds reached) THEN outputs A0 and A1 and B3 go LOW THEN power to LCD display module goes LOW



IS it possible to program a PIC controller to do all that? and IF so any ideas what kind of external circuitry I'd need as well?
Can you drive an LCD circuit direct from the same PIC chip, or would it need a seperate controller to do this, and if so how would you interface the two?
sorry lots of questions and I'm showing my ignorance of PIC's and programming, but you cant learn if you don't ask questions.





the 3rd and 4th lines of the LCD display and the extra 2 temp circuits are not needed, it would just be handy if I had a 4 line display instead of a 2 line one, or something like 240x 128 LCD Screen



HOPE I've made that clear enough to understand but the last programming I did was in college and they had only JUST got a computer with 4K of ram (yes 4K not MEG) and a printer attached, they hadn't even got a display of any kind, this was in 1977! how things have changed



Future "mods" (IF I ever get this working) and have the LCD SCREEN instead of the 4 line display would incorporate a fuel level sensor that either shows a bar graph of fuel level with the word FUEL next to it, (or above it if this was a vertical bar graph) and the sensor would be a fuel level sensor which I think the values are 240 - 33Ω