Definitely in over my head!

Development Boards Arduino
1

Just as the title implies, I’m definitely feelin like I’m in over my head with trying to understand this Arduino stuff. I have been reading and researching on this for a little while, but I still feel just as confused as when I started, so I thought I would ask you guys for some help in understanding all of this.

I just purchased a project vehicle (1986 Ford E-350 Extended Van) and it has a dash that seems like it really belongs in the junkyard. I’m not sure if some of the gauges are working properly and others are nonexistent or inoperable. While my goal isn’t to turn this into KITT (it would be cool though lol in a nerdy kinda way) I at least want to bring this van up to speed a little on the instrument panel and add certain things to it. Once I start working on the camper part of this van I’ll also start adding in other electronic control or display, but that will be tackled later.

Right now I’m having trouble understanding just how much these little Arduinos con control at any one time. The first major part of this van electrical project I want to tackle is the speedometer/odometer, engine’s vitals, and maybe the transmission’s vitals. I do know that I want to use the 7 segment LEDs to display information such oil pressure, coolant temperature, tachometer, battery voltage, GPS speed and the like. All the information will be displayed on the instrument panel and then some of it I want to set up as a HUD also.

  1. Should I tackle this large integrated project with one “large” Arduino or several “smaller” ones such as the Teensy LC or the Adruino Pro Mini?

I see benefits to both approaches but I’m not sure what is the best option to use since I do plan on expanding on this later once I’ve gotten the hang of using these Arduinos.

  1. I chose several “smaller” Adruinos vs one “larger” one is there a way that I can put them all through one USB connection, such as a BUS (still not sure how that works), so that I can select any one of them for diagnostics or program loading?

  2. If I chose the Teensy (which I really like because of the already included USB connection for program loading), how many 1/2/4-digit 7-segment LEDs can I control with one Teensy if I’m using some MAX7219’s to help drive the LEDs? (no more than 4 digits total per MAX7219)

  3. Assuming the answer to question #3 is multiple at least, can I run code on the Arduino/Teensy to evaluate different types of information from various types of sensors and such to display their values on the appropriate 7-segment LEDs? I would like to at least have Arduino/Teensy controlling all the engine data, another for speedo and odometer/trip odo, and other chassis information, another for controlling the LED brakes, turn signals etc, and so on.

Sorry for being such a NOOB, but I at least do have some limited understanding of electronics. I’ve been an avionics tech for aircraft for the last 15years but I’ve never dealt with the actual electronics design part of all this. I know that the answers given will most likely bring more questions so please forgive me.

Thanks!

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First thing to do is to find out what the 1986 van’s computer can spit out in terms of information about the engine. Is the speedometer’s gauge being fed from the CPU or is it mechanical? And so on…

I think for a 1986 vehicle, you’ll find that most gauges are mechanical and will take some creative engineering to make an Arduino be able to read those… You may get lucky and find some of the gauges’ being fed from the CPU like oil pressure, fuel…

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'86 is definitely pre-OBD-anything. It’s EEC-IV. Pretty much useless for what you’re thinking about. No real standard communications methods, etc. Sure, there’s ways to get in there and get info…not easy by any stretch. As noted above, you’ll be doing a lot of mechanical-electrical interfacing.

mos68x:
Right now I’m having trouble understanding just how much these little Arduinos con control at any one time. The first major part of this van electrical project I want to tackle is the speedometer/odometer, engine’s vitals, and maybe the transmission’s vitals. I do know that I want to use the 7 segment LEDs to display information such oil pressure, coolant temperature, tachometer, battery voltage, GPS speed and the like. All the information will be displayed on the instrument panel and then some of it I want to set up as a HUD also.

Oil pressure / coolant temp / transmission temp - resistive senders, analog-digital converter

Tach - circuit to tap off the tach output from the distributor, 12v->logic level converter plus filtering

Battery voltage - ADC, easy enough

Vehicle speed - sure, GPS for the easy way, hall effect sensor with 2 magnets epoxied to the front u-joints at the back of the transmission, or maybe you’ll get lucky and there’ll be a VSS output on the tranny itself.

  1. Should I tackle this large integrated project with one “large” Arduino or several “smaller” ones such as the Teensy LC or the Adruino Pro Mini?
Plenty of inputs on a Teensy LC, basically any Arduino short of the mini versions
  1. I chose several “smaller” Adruinos vs one “larger” one is there a way that I can put them all through one USB connection, such as a BUS (still not sure how that works), so that I can select any one of them for diagnostics or program loading?
Sounds like that's way above your pay grade.
  1. If I chose the Teensy (which I really like because of the already included USB connection for program loading), how many 1/2/4-digit 7-segment LEDs can I control with one Teensy if I’m using some MAX7219’s to help drive the LEDs? (no more than 4 digits total per MAX7219)
Can control as many as you want with a couple of shift registers on an output.
  1. Assuming the answer to question #3 is multiple at least, can I run code on the Arduino/Teensy to evaluate different types of information from various types of sensors and such to display their values on the appropriate 7-segment LEDs? I would like to at least have Arduino/Teensy controlling all the engine data, another for speedo and odometer/trip odo, and other chassis information, another for controlling the LED brakes, turn signals etc, and so on.

It’ll all run on one board.

Do I detect a drive by poster?

4

I still have to verify evenrything to be absolutly certain, but I think most of the sensors on the engine are electrical. However, even if they aren’t I shouldn’t have too much of a problem finding a suitable newer year sensor replacement to make them electrical. The speedometer isn’t electrical though so that is one that I know that I’ll probably just switch over to GPS anyways so that it’s always accurate no matter what I do with the drivetrain and wheels. The vehicle stuff I’m not worried about it’s this Arduino stuff that I’ve never dealt with or have any working knowledge of, that’s what I really need help with.

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I highly suggest that you search for other projects with a similar year vehicle. I don’t think you know what you are getting yourself into.

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mos68x:
but I think most of the sensors on the engine are electrical. However, even if they aren’t I shouldn’t have too much of a problem finding a suitable newer year sensor replacement to make them electrical.

That's the easy part...analog to digital.

The speedometer isn’t electrical though

...which is why I suggested the magnets on the driveshaft.

so that is one that I know that I’ll probably just switch over to GPS anyways so that it’s always accurate no matter what I do with the drivetrain and wheels.

False assumptions...

The vehicle stuff I’m not worried about it’s this Arduino stuff that I’ve never dealt with or have any working knowledge of, that’s what I really need help with.

In other words...everything...
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codlink:
I highly suggest that you search for other projects with a similar year vehicle. I don’t think you know what you are getting yourself into.

A massive headache…I already understand that lol but it still has to be done, so now I’m here trying to figure out what the limitations are to these Arduino’s since all the videos and tutorials I’ve seen have only tackled one thing or another individually and not a group of sensors with different types of information.

skimask:
That’s the easy part…analog to digital.

I'm just planning on reading the V out from the sensors since they'll all be analog and then have the Arduino change it from that to the appropriate value on the 7-segment LEDs

False assumptions…

The only way that it would be a false reading is possibly when it is standing still or when the receiver loses track of one or two GPS signals, and even that is only if the receiver only has less than 5 that it is tracking. Or if you're in a highly dense area such as downtown Chicago and you're hanging out with all the skyscrapers. But unless I find a better one I'm planning on using a GPS receiver that I found on SparkFun.

https://www.sparkfun.com/products/8975 5-10Hz 66 channel so this should work fine until I can find one that can go to 20Hz reliably

In other words…everything…

Pretty much everything about the Arduino’s lol

But…to bring this back on point a little, I think someone already mentioned that as long as I was using the MAX7219 or the MAX7221 chips I could control the 4-digit 7 segment LEDs with just one Arduino/Teensy.

If I had all the input pins populated with various sensors will the Teensy (48MHz) be able to cycle through the code, convert the different voltages as necessary and display them on their respective LEDs without any visible or noticeable lag or choppiness in the display?

8

“lol” “rofl” “lshism”

ya, it’s just that funny…

mos68x:
A massive headache…I already understand that lol but it still has to be done, so now I’m here trying to figure out what the limitations are to these Arduino’s since all the videos and tutorials I’ve seen have only tackled one thing or another individually and not a group of sensors with different types of information.

No limitations. One thing at a time. How fast do you REALLY need to read a sensor to update a gauge? Even the slowest of slow MCU's can and will do it much faster than your eye can see and your brain can process.

I’m just planning on reading the V out from the sensors since they’ll all be analog and then have the Arduino change it from that to the appropriate value on the 7-segment LEDs

...hence the term "analog to digital converter". Yes, there isn't very many more ways in the world to do it now is there....

The only way that it would be a false reading is possibly when it is standing still or when the receiver loses track of one or two GPS signals, and even that is only if the receiver only has less than 5 that it is tracking. Or if you’re in a highly dense area such as downtown Chicago and you’re hanging out with all the skyscrapers. But unless I find a better one I’m planning on using a GPS receiver that I found on SparkFun.

GPS can only tell you how fast you WERE going, not how fast you ARE going. You can only calculate where you WERE, not where you ARE.

If I had all the input pins populated with various sensors will the Teensy (48MHz) be able to cycle through the code, convert the different voltages as necessary and display them on their respective LEDs without any visible or noticeable lag or choppiness in the display?

Look at the datasheets. How fast can the MCU read an analog input? How fast can the MCU convert the data to a readable format? How fast can it display it? How fast is fast? How fast do you need it to be? Do you really need a 20Hz GPS module? Is your vehicle able to change speed so much inside of 50 milliseconds that you REQUIRE a 20Hz update rate from the GPS?

…me thinks not…