Multiple sensors/displays

Projects General Guidance
1

Thinking of ways to go about a project. Not sure how much an uno can handle while keeping up with a bunch of sensors. The project is essentially building a full digital guage set for a vehicle.

Each sensor would have its own display. Thinking about those 4 digit tm1637 displays for most of them. . coolant temp display. Tachometer. . speedometer will be a custom display probably running the same driver chip only larger digits. Would be nice to add a odometer. I have a 7 digit led display from an ancient motorola mobile phone. Trip miles would be nice too.

Thinking about adding a clock/trip timer.
And digital fuel reading approximate gallons remaining from the fuel level sensor.

The speed, rpm, odometer would be the important things to keep up quickly. .

I may add a couple things although at this moment it would be nice to have some input/recommendations etc.

Coolant temp and fuel level would be interpreted from analog "voltage divider" type sensors. Since both are resistance based sensors. Tach would be gathered from the distributer tach output divided by 6? Being a v6 engine. Speedometer would be an infared sensor that is currently attached to the speed cable. Would have to convert the pulses to a MPH reading. Then how to make an odometer work from those same pulses from the infared sensor. (Sensor was used on cruise control equipped models)

Thoughts, tips, ideas welcomed. Anything that would help with this project. Boards libraries, sketches that would work better for this.

2

A basic Arduino could handle all that stuff. Recommend Nano/Pro Mini/Micro over Uno, as you will be building your own designed circuit rather than using pre-made shields.

Use 7-seg display modules based on max7219 chip not tm1637, otherwise you will quickly run out of pins. Max7219 displays can be chained together, sharing the same pins. If buying separate displays and chips, which may give you more choice of size & colour, choose common cathode displays, not common anode. Using separate chips & displays will also allow you to connect up to 8 digits to a single max chip, but probably best not to mix different colours on the same chip. Does not mean a single 8-digit display, could be 2 x 4-digit, or any combination of 1, 2 or 3 digit displays.

The 5V regulator in an Arduino won't be able to run multiple 7-seg displays, so get a 1.5~2A 12V-5V DC-DC converter module, one designed for auto use.

For a clock, you will need an RTC module, which will use A4 & A5 pins (=i2c bus), robbing you of 2 analog inputs, so think about how many analog sensors you will have. Nano has 2 extra analog pins compared to Pro Micro. More analog inputs can be added using i2c bus anyway.

Larger displays may need higher than 5V to operate, so max7219 not suitable, but you can use tpic6c595 or tpic6b595 chips, one per digit, and chain those to the max7319 max7219 chips.

For night and day driving conditions, you will need to control the brightness of your displays. The Max chip has 16 selectable brightness levels. If you need to use the tpic chips, their brightness can be controlled by connecting their OE pins to a single Arduino PWM pin.

An automobile is a hostile environment for electronics. Care must be taken to avoid high voltages and power spikes from causing malfunctions & even damage to the circuits. This makes such projects above beginner level. But you can build, code & test on the safe environment of the bench first and build up your skills & experience.

3

Cool. Ordered a few max7219s i actually do have a mega2560 pro mini . it probably isn't name brand but that should work. Many pins on that looks like 54 digital pins. 16 analog. Not sure if i would need that many but it leaves room for expansion i suppose. I would have to look into a stable regulator to run from. Brightness control will be a plus as well. I have some Man6980 7 segment displays. For the cluster size any larger would not look proportional. The larger display will be for speedometer. Possibly tachometer as well but everything else will be a smaller display. Odometer is the smallest display. I just have to find out the type of display that is using. I haven't removed the display from the old phone yet. But being a small 7 digit led display it would be perfect for an odometer display panel. .

I guess the big thing is the coding to change certain value readings to display what i want where i want it.

.

4

Hi.

You might like to think about using an Android tablet as a single display for all your instrument outputs.

It sounds like you are after a layout with individual physical displays so a tablet might not appeal. Even so, the tablet would be useful for testing purposes. The Arduino would assemble all the data and send it in one sentence via Bluetooth to the tablet.

John.

5

i actually do have a mega2560 pro mini

I would not recommend those either. Can't use them with breadboard or stripboard.

6

PaulRB:
I would not recommend those either. Can't use them with breadboard or stripboard.

It would be complicated. You kinda could but would require a bunch of hardwire connections to split the rows out. Plus i do not believe i would need so many pinouts as that has on it. I can save that one for something else later down the road. The fact that the max7219s can be shared will reduce required pins greatly. . right now i believe i would only need 2 analog sensors running. Unless i add something else. It actually would be cool if there were a sort of fuel metering device that would know the amount of fuel passing to the engine for a MPG readout as well. (I work on cars so making something like that hooked into the main fuel line wouldn't be a new thing for me. I have redone most of the fuel system already) .

Theres a part of this that is actually kinda funny. The target car for this project is from 1985 . carbureted. Basically no electronics at all. I mean it doesn't even have air conditioning or cruise control or anything. .

But the thing that got this idea started was replacing the "volts" idiot light with a digital voltage display where the light was. Surprisingly the size of the light was perfect to fit that in. And looks pretty good. Then i look at it and just imagined it being fully digital. Not super flashy looking just something that has that sort of 80s looking basic digital guage cluster. And getting the parts made up to fit the displays into a factory cluster.

Its a pretty simple cluster honestly. As it is now it only has a speedometer and a fuel guage and 8 lights. It doesn't even have a trip meter. Just the odometer. Found out that was optional.

HillmanImp:
Hi.

You might like to think about using an Android tablet as a single display for all your instrument outputs.

It sounds like you are after a layout with individual physical displays so a tablet might not appeal. Even so, the tablet would be useful for testing purposes. The Arduino would assemble all the data and send it in one sentence via Bluetooth to the tablet.

John.

Honestly do not even have a tablet right now but a Bluetooth connection to the system may not be a bad idea. (Phone could work)

But yeah i would like to stick with the LED displays. Some nice red or amber displays ... Just has that 80s vibe. And being a 1985. . this car didn't have digital option. .. I mean. The trip guage was optional. It is a pretty basic car. (Probably one of the reasons i like the car) basic car with a stock stereo fitted with a usb mp3/ Bluetooth player. And better sounding speakers.

7

Phone would work. I suggested a tablet cos you aim to get data from quite a few instruments. A tablet provides more real estate.

Consider the Bluetooth option as an aid to your development work, rather than part of the operating installation.

I use Bluetooth and phone to communicate with an Arduino (Nano) based speedo on my car, but only in development not operation

What is the car?

John.

8

Led bar graphs might look good for some instruments. You can wire them up the max chips too. Like these.

bargraph-all-S.jpg
bargraph-all-S.jpg600×600 42.8 KB

bargraph-all-S.jpg
bargraph-all-S.jpg600×600 42.8 KB

9

HillmanImp:
Phone would work. I suggested a tablet cos you aim to get data from quite a few instruments. A tablet provides more real estate.

Consider the Bluetooth option as an aid to your development work, rather than part of the operating installation.

I use Bluetooth and phone to communicate with an Arduino (Nano) based speedo on my car, but only in development not operation

What is the car?

John.

I may do something like that for testing to make sure everything is working with the sensors.

Its a 1985 chevrolet celebrity. Pretty basic 4 door sedan. Nothing fancy i just like the car. Had it for years. It was my daily until recently it has had some engine issues since day 1. At first it was just another$300 beater but ive grown to liking the car plus it has survived this long with the issues it has. I don't even know how it has made it this far. Bought it with 152k miles on it. It was literally on a trailer on route to the scrap heap. Offered the guy 300 bucks and drove it home. Sticking valves backfiring overheating among many other engine issues that should have been taking care of. Blows oil everywhere has alot of issues but it has always ran and drove DAILY for years. Not long after i got it and got a feel for it and liked the car i said if you make it over 200k you'll get a good rebuild and fix up. And to my surprise its sitting here with 207k. Drove it until i parked it. Only reason i parked it is to redo the engine and fix up other issues. Hopefully get some bodywork Done and painted as well.

10

Sounds like a labor of love. The instrument display would be a nice touch. A little bit back to the future.

Doing as much prototype testing at the workbench is really important. Testing devices while driving is hazardous because it distracts the driver. This is where the Bluetooth option pays off.

John.