Converting DS18B20 output to 8 x 24 led matrix

[MrDEB]

While waiting for the ICSP expander boards I have been mulling over ideas for an 8 x 24 led matrix display to display the temperature of the beer cooler I am kinda in charge of. Our membership voted to increase the refrigeration system from 6K BTU's to 12K BTU's ($4100 worth of equipment) and wanting to display the present cooler temperature which we try to keep at 34 degrees. We serve draft beer and going from a cooler temp of 40 degrees down to 34 has saved a-lot of beer foam-over (the beer foams less the cooler it is We went from 10 gallons over-foam to 1 quart aprox in a 7 day period.)
Anyway contemplating how to best achieve the desired results. Using basically the same code as my 8 x 8 scrolling matrix project but using a 200 ohm resistor for each of the 24 anodes (using 3-common cathode 8 x 8 matrix displays)then use 3 - uln 2803 to sink the current (idea from Graham Mitchel's Tetris game).Yes maybe could get by with one uln2803 but may exceed the chips sinking spec.
My idea hangup is converting the DS18B20 output to the led matrix.
Using
Code:
IF DS18B20.Find THEN
DS18B20.Convert
GetTemp(TempA, TempB)
TempF = ((TempA*10+TempB/1000)*9/5+320)/10

Then using CONST arrays to display the value of TempF on the LED matrix. Basically converting TempF to a 16bit longword I think?? Unless there is a method to directly convert the DS18B20 10 bit output to a 16 bit output (Pretty sure I need the 16bit output for the display (8 bits per digit) but need more research.
Any ideas are welcomed.

 

[MrDEB]

OUPS! the DS18B20 output is user defined from 9 bits to 12 bits but still need to be able to display the Value of TempF on an 8 x 24 matrix.

 

[JonSea]

TempF from your equation is in degrees F. It should never go above 99F, or you have a really crappy refrigeration system. And it should never get anywhere near 0 or into the negative range. So you have 2 digits to display.

The bits of resolution of the temperature sensor have nothing to do with the "bits" on the display.

 

[MrDEB]

I was kinda thinking out loud. Still contemplating using a CONST array look up table. This might be the easiest? to display what TempF is. Unless the LCD routine output can be used but ?? don't think so. The display I want is to scroll across the 8 x 24 matrix.
"Present beer temperature is (TempF)
So if TempF = 40 degrees then the matrix to display "Present beer temperature is 40 degrees"
if TempF = 34 degrees then the matrix to display "Present beer temperature is 34 degrees"
To really get convoluted, have a sensor on each beer tap then 2- 7 segment led displays over each tap but that's going too far over the edge.
Hopefully going with a KISS approach. Just need to go down the right road of ideas to achieve goal.

 

[MrDEB]

I need to rethink method to configure the hardware. Perhaps 3 - 74595's as I see several other similar designs using same.

 

[JonSea]

Seems like a lot of overhead to display 2 digits of temperature. If I counted right, 39 characters of overhead to display 2 meaningful digits. No matter, you have your reasons.

I already explained this clearly in your last go-round with matrix displays. I'd suggest assembling the data for the non-changing part of the message (i.e., "The temperature of....") and add the data for the two digits each time the message is displayed. See my previous discussion.

Using shift registers is a good idea (3 shift registers instead of 24 port pins) but the '595 is not the best choice. You need a power shift register to handle the current of 8 illuminated LEDs in a given column. The TI TPIC6B595 is one possible choice, which is in stock at Digikey for $1.74 each. Alternatively, you could use '595 shift registers to control ULN2003s.

 

[MrDEB]

Thanks.
Yes I plan to have the non changing data as say "dim Message_Data as word" then using TempF as a changing variable to insert on the back end of "Message_Data"
Found a circuit ,seen before but never considered A dot matrix led display project for an 8x8 or 5x7 led matrix.
They are using the uln2803 and 4017 counter. Using 3 of the uln2803's and two 4017's plus 24 port pins w/ resistors.
Going to look at your suggested TI TPIC6B595

 

[MrDEB]

WOW If I am interpreting correctly, I don't need the uln2803 if I use the The TI TPIC6B595.
Application diagrams/ circuits indicate the chip can sink 1.8A.
a pic, 24 resistors, 3 led displays and three TI TPIC6B595's
now some research on part availability, price and weight the fact if I have the 4017's on hand. No problem if I can use BILL ME LATER

 

[MrDEB]

Well back to the drawing board
Was going to use some 20mm square CC red matrix but looking through my boxes of parts I find some Red/Green 30mm square matrix's that I have for a discontinued project but they are CA
need to rethink direction. The uln2803's I don't think will work? for the CA displays but in my bike project I use TD62783 which is similar to the ULN2803 to drive the anodes.
RESEARCH

 

[MrDEB]

Well I bite the bullet, I purchased 10 -CC 8x8 led matrix from Tayda electronics

 

[MrDEB]

STOP the presses. I forgot I also ordered some TI TPIC6B595 for good measure

 

[dr pepper]

The do a high volatge verson of the '595 as well as the highcurrent one.

 

[MrDEB]

My plan is to go with the TPIC6B595 as shown in this example but using the TPIC6B595 instead of the 74HC595
Making a 8×40 LED matrix marquee using shift registers | Embedded Lab
Got all the components except the LED matrix's which should be here today or Monday.
Using an extra 18F4520 but could use a smaller pic but why bother if I have it as extra.
My plan is get the circuit wired up then configure a working SF code THEN include the DS18B20 as a sub routine.
Have a 7805 and wall wart to go with the circuit. The pic and associated components from beer cooler thermostat project that is no longer needed as we upgraded the cooling system from 8K BTU's to 12K BTU's. The older system couldn't keep up to the load from opening and closing the glass doors.
The matrix is just to welcome customers to our beer booth and inform them that the beer is 34degrees (the walk-in cooler temperature) Be going way overboard if I put a sensor on each beer tap and a two digit 7 segment display per tap but a cool idea for sure.
Turns out at 34degrees we will have the coldest beer in all Lemhi County as per the refrigeration installer. Most of the coolers are set to 38 - 40 degrees.

 

[JonSea]

....Turns out at 34degrees we will have the coldest beer in all Lemhi County as per the refrigeration installer. Most of the coolers are set to 38 - 40 degrees....

Is that a good thing? According to Craft Beer Temple:

 

[dr pepper]

Sounds good.
You can get the 18b20 in diffrent flavours, they do one in a stainless tube, might be better for a fridge.
Why not have 2 or 3 and caluclate the average.

I have given up booze altoghter now, but I used to like cask ale, which is kept at room temp, or should I say cellar temp, this country however most of the time is a lot cooler.

 

[MrDEB]

I really like the dark beers myself.
Some people think lager is just a name. It's "stored away" which is what lager means.Then There's the beers name such as stout indicates alcohol content. I recall beer being the lowest and Bock being the highest Ale and stout are in between.
As for our selection of beer we sell Coors Light is biggest seller then Alaskan Amber, Bud Lite (yuck!) Konokini and a dark beer made locally called Mt. Borah. Then all the different cans and wine coolers.
Average is considered but really not wanting to go that far. I have 5 of the stainless steel encased DS18B20 sensors.
Hopefully get this project done before August 15th as that is close of escrow on house here in Salmon. Moving closer to grand kids.
Sounds like Jon enjoys a good beer

 

[JonSea]

Me? No, actually, I don't drink beer or coffee, but don't tell anybody, as that's not a popular place to be in Seattle! Nothing against either, they're just not my taste.

 

[MrDEB]

Well lets see, wine or scotch??

 

[dr pepper]

Bock I think I tried that way back, yeasty part brewed ale, liked it.
In the uk going back a hundred years or so butter beer was a daily drink, because the water wasnt safe, the alcohol content in beer made it safer being an antibac.
One of the reasons I stopped was the lack of anything worth drinking, all the popular brands to me taste like soap, I think they pump all kinds of chemicals into them nowadays to increase production, maybe this hasnt got through to the u.s. yet, when I was last there I noticed food joints were way better than here, I dont think you guys settle for junk.