# Making a Digital Compass for my Car

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#### falieson

##### New Member
I am pretty new to electronics I have only taken basic CPE and EE class at my college before I decided that nodal analysis and finding the resistances of a circuit just wasn't for me.

But here I am, and I want to make a digital compass for my car and I was wondering if someone could help me put together a part list of things I would need. I think I already found a good compass output but I just don't know how I get it to read out to a 2x7-segment-LED

Compass - https://www.dinsmoresensors.com/1490spec.htm

#### dknguyen

##### Well-Known Member
Get a microcontroller and an LCD screen with a serial backpack. You can code the microcontroller to read the readings from the compass and send serial messages to the backpack. The backpack will display whatever you want on the LCD screen for you without you needing to deal with every little display element.

I am not sure what the output on that sensor is- analog or digital. Digital takes more work to read from since you need to use serial protocals. Analog is easy since you can just use an uC's ADC to read the voltage.

#### audioguru

##### Well-Known Member
What do you want to see on the two 7-segment displays?
The sensor that you selected has only 8 direction outputs. It is designed to light one of 8 LEDs in a circle. Therefore its resolution is terrible.

#### falieson

##### New Member
audioguru said:
What do you want to see on the two 7-segment displays?
The sensor that you selected has only 8 direction outputs. It is designed to light one of 8 LEDs in a circle. Therefore its resolution is terrible.

Oh, I didn't realize that that is what the digital sensor did. But I guess that makes sense! Its been a while since I thought 'like a circuit'. =)

How would you suggest I go about doing this?

#### dknguyen

##### Well-Known Member
I would get a regular compass, personally. It works when the car is off.

#### HiTech

##### Well-Known Member
dknguyen said:
I would get a regular compass, personally. It works when the car is off.
LMAO!!!!!

You know that at many truck stops they sell digital compasses that compensate for vehicle magnetics and are pretty accurate. I saw one selling for under $40 that operated from internal batteries or gigarette socket and even included inside and outside temperature sensors, elapsed timer and a photocell to automatically adjust the backlit display. I couldn't assemble one from scratch for that small price! That one will work with the vehicle shut off too when in battery mode! #### falieson ##### New Member HiTech said: LMAO!!!!! You know that at many truck stops they sell digital compasses that compensate for vehicle magnetics and are pretty accurate. I saw one selling for under$40 that operated from internal batteries or gigarette socket and even included inside and outside temperature sensors, elapsed timer and a photocell to automatically adjust the backlit display. I couldn't assemble one from scratch for that small price! That one will work with the vehicle shut off too when in battery mode!

The car already has inside and outside temps =) But I guess I really just wanted to make one because I wanted it to look like part of my car and thats why I wanted the 7seg. displays. So... any help in how to make one rather than alternatives to making one.. would be great.

#### dknguyen

##### Well-Known Member
You could still take the output from a digital compass and read it into a uC and have the uC display whatever you want on an LCD. For example, N, S, W, E, degrees, etc.

#### HiTech

##### Well-Known Member
falieson said:
The car already has inside and outside temps =) But I guess I really just wanted to make one because I wanted it to look like part of my car and thats why I wanted the 7seg. displays. So... any help in how to make one rather than alternatives to making one.. would be great.
At the risk of being redundant, they do make rear view mirrors that have digital compass, temp. indicator and also auto-dim during nightime driving. They are under \$100 US, installed and that would look very professional and factory like.

#### falieson

##### New Member
thanks! That was actually the first thing I looked into, and I haven't seen one yet for the bmw convertible - the power leads to the mirrors usually come from a sunroof while the only power I have to go on is for the overhead lights and I haven't read anywhere how to get at that yet - I might take a look at it though this weekend now that its here and I haven't gotten any better suggestions in how to actually make the display I want.

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