This is a Monitor system for Travel Trailers, Pop Up's and other RV's. I have made provisions for two displays, one inside and one outside. A single button for each display steps through the modes. Modes include
Battery Voltage:
Fresh Water Level:
Outside Temp:
Inside Temp:
Cycle The Data Displays:
Off:

Each Display is independent of the other. That is they can be in any mode regardless of the state of the other display.
I haven't bread boarded this yet but it's working on my EasyPIC V7. I'm still waiting for some hardware to complete the first target board. So there will no doubt be a Version 2.0, but I did want to hear any comments you guys may have as early as possible.
Included are:
Design Doc
Schematic
Port Chart
Assembly Docs for the OEM hardware bits I bought
All the Source Code
And I did find some handy GIF files for the schematic drawing so I left them in the package.

I'll update this Blog with Pictures when I have enough to be meaningful.

Thanks For Looking

Dick

Update 6/24/2013

It's been a busy couple weeks! I ran into Ram management problems and had to reorg the code to keep all the ram usage in the lower bank, but so far I've managed to avoid manual bank switching.

I changed the Temp Sensors to the DHT22 modules. Mostly because they come in a package that is easy to mount outside. Also getting Relative Humidity isn't a bad thing. The timing on these things is pretty critical especially if your running an interrupt, but it's doable. A good "O" Scope is almost required for the adjustments. I have one coming, hopefully today but so far I have been able to get it working without. It really is required to wait two seconds between sampling, but when your talking about Temperature and Humidity that's not an issue.

I did manage to fab and install the Bezels for the LCDs and buttons. It's just Plexiglas painted on the back side but looks pretty good.

Also I've started the  build of the prototype circuit board. Not much done yet but it's a start.

Here are a few pictures of what I have so far. I'll post updated software after I've fine tuned the DHT22 com timing with a scope.

Thanks for looking.

Dick

Update 6/25/2013

Got the new Scope yesterday. It's the low end but does 25 MHZ so it's plenty for my projects.

I was able to refine the data capture from the DHT22. I installed a delay in the One (1) Bits so I'm guaranteed to start the loop in the next start bit. Also I disabled Interrupts in the capture routine which made it a lot more consistent. The error count is down but I'm still going to change it to use counter Zero to measure the bit time. I figured out how to get it counting at a 1 usec rate so the delta between a Zero and a One will be easy to detect. This method will start me as far left in the Start bit as possible which is one of my problems. To get the data logged and For Loops counted I was not getting back to the top in time and got hung up looking for the start bit when in reality I was in the data bit. This was especially true when the Interrupt routine took some of my time. I was a little surprised because I'm running the 16F76 at 16 MHZ. It's just that the timing for the DHT22 is in the Micro Secs and there isn't a lot of time even at 16 MHZ.

Here are some pictures of the Data Stream and the Scope in general. I like the Scope. It's intuitive to use and unlike others I've seen very reliable at triggering. BTW it's a OWON PDS5022T.

Thanks For Looking

Dick

Updata 6/26/2013 10:15 PM

This is Revision 2. I changed the Temp sensors to AM2303 to Get Temp and Humidity. The Deg. "C" to Deg. "F" conversion covers -4C to 124C. I hope I never see those numbers while camping. I am using Timer0 to detect errors and measure the Data Bit time. I haven't seen any code in MBasic for reading these devices so here it is. I tried using Delays for the measurement but it was unrealible, this method works much better. I have been running it for about 24 Hours now with no errors at all. I'll include a link to a short Video. The comments describe what I've done pretty well.

Here is a link to a short demo video. It's case sensitive

http://SDRV.MS/14YOJmj

I can't seem to get the link to work with the insert video button. 

Thanks For Looking

Dick

BTW The Electronic Goldmine has these LCD Displays on sale for $1.49. I Don't know how long it will last, but if yoy could uses some, they work fine with the EasyPic V7, both the hardware interface and the LCD Libraries.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G19319

Dick

I realized that six water sensors for a 12 Gal tank is just too many. So now I've changed to also display the water level in the gray tank. I'll have three sensors in each tank.

The prototype board is completed and tested. Everything is on connectors so I can pull out any of the elements without removing cables. I made up some pretty long cables for the displays just to be sure I won't need drivers when installed in my Pop Up. All is working well.

Here are a few pictures.

Thanks for looking

Dick

Version 4 Adds a Time Of Day Clock. I chose a DS1302 chip because it isn't I2C and allowed me more freedom choosing I/O Pins. The Alarm is installed and alerts when the Battery is Low.

I also changed the Power Supply. I measured the Temp on the regulator and found it to be nearly 200 F. In the great outdoors this would be even higher. The total current was approaching 400 MA out of the Battery. So I changed to a picoPSU-80 Power Module. It's very efficient at 94% below 1 AMP draw so there is really no heat in the box. I now measure about 3 Deg. C heat rise from ambient. The current draw from the battery is also down to 230MS worst case with the more efficient PS. This Supply Crowbars on high voltage so I added a Diode drop in the feed line to be able to have the battery just a touch higher. I found that when the PS Crowbars the +5 VDC doesn't go to zero and hangs around 3.2 VDC. This is a problem with the battery voltage at max into the A to D RA1. The PIC spec no more than .3 Volts higher than VDD. So since the PS is designed for small Computers it has a Power Good line output. I used this output to control two relays that completely turn off both the VDD and Battery feeds and this is working very well.

I finally had to deal with the high Ram Bank. I put all the Text in CONST declarations and moved them to a Print Buffer in the high RAM Bank and printed from there. It was easy to manage the IRP_Bit and kept all the management in the Sub_Routine Module.

I've got more but the system just won't add it. I'll try again tomorrow. 

Thanks for Looking

Dick 

Some more testing and I can install it in may camper. It's stable now and I have tested for three days now without any anomalies. So I believe it's done. I'm out of I/O and Ram. I'd have to change processors to do any more and I can't think of anything else I'd want.

As a side note: I had a failure in my EasyPic V7 that completely disabled programming. Working with Customer Support at MikroElectronica I was able to determine the problem was U10 Voltage Translator in the programmer. It's located under the can. I found a new one at Mouser and replaced it and now all is well. Just wanted to give a shout out to Marina over in support. She stayed with me all the way and was very helpful. In fact without her help I would have never gotten it fixed.

Be sure to read the Design Doc to see how I solved the problem of setting the clock with only one button for input.

Thanks for Looking

Dick 

It's all installed now. Here is a link to some pictures of the Pop Up with the system installed. It's working fine and version four is the final version.

https://skydrive.live.com/?cid=ae67fff392766057#cid=AE67FFF392766057&id=AE67FFF392766057%215095&v=3

We did the remodel last winter. This is a 1977 Palomino Yearling Pop Up Camper a real oldie but goodie.

Thanks for looking

Dick

WOW Downloaded: 255 times that's eight bits worth.

Really just trying to bump this on the home page ;-)

Dick