display trans shift position

Hello

I have modified the shifter mechanism in a custom vehicle so that I can't
use the stock shift position display.

Would it be posible/practicle to use a single character 16 segment or led
matrix unit to display the characters1,2,3,D,N,R,P from a signal given by
a magnet activated reed switch for each position as the switch is closed
by a magnet attached to the shift lever? What driver/controller might I use?

Any comments and opinions will be appreciated.

Orville

LCD that displaysd your characters? - yes

from a signal given by a magneti activated reed for each position? -maybe
You mean for every position of the shifter, a separate signal on/off signal is present for position? If so, yes, easily.

I will assume that you just want this done as quickly and easily as possible (as opposed to using it as a stepping stone to other electronics projects):

Any tiny text LCD display will do, maybe a backlit one From:
http://www.robotshop.ca/home/products/robot-parts/electronique-lcd/netmedia-2x16-rohs-lcd-blue.html

Your application is super simple for any MCU. Maybe a PICAXE? Cheap, no programming hardware needed, made for classroom experimemnts. Maybe even just go with their LCD serial kit:
https://www.electro-tech-online.com/custompdfs/2007/11/axe033.pdf

Assuming your reed is a 0-5V signal that won't blow up your MCU when connected to it, you just need to connect the serial port on the MCU to an LCD+controller and use one big IF statement in your code.

IF pin 1 is high, display D, else
IF pin 2 is high, display R, else
etc...

If you live near a university, go check out their electrical engineering program and see if they have final-year student design projects. You might be able to secure yourself as a client where you give specifications and the students design and make the thing for you.

Orville said:

Hello

I have modified the shifter mechanism in a custom vehicle so that I can't
use the stock shift position display.

Would it be posible/practicle to use a single character 16 segment or led
matrix unit to display the characters1,2,3,D,N,R,P from a signal given by
a magnet activated reed switch for each position as the switch is closed
by a magnet attached to the shift lever? What driver/controller might I use?

Any comments and opinions will be appreciated.

Orville

Click to expand...

hi,
A simple option would be to have a 'strip' display,with each character being back lit by say an LED from its own positional reed switch.

eg strip = ; ' 1 2 3 D N R P'

ericgibbs said:

hi,
A simple option would be to have a 'strip' display,with each character being back lit by say an LED from its own positional reed switch.

eg strip = ; ' 1 2 3 D N R P'

Click to expand...

If the existing indicator uses such a strip, you could get even simpler and wire your reed switches into its backlights.


Torben

Torben said:

If the existing indicator uses such a strip, you could get even simpler and wire your reed switches into its backlights.


Torben

Click to expand...

Hi Torben,
I also agree with the old saying 'keep it simple', why over complicate a task.

Regards

If you use a 7 segment LED, you can get all those characters. "N" isn't possible but you can use "n", and "R" looks a bit funny. "D" will look like "0" unless you use "d"

However, you can use diodes directly from the reed switches to the series resistors.

By my count you need:-
"1" 2 diodes
"2" 5 diodes
"3" 5 diodes
"d" 5 diodes
"n" 3 diodes
"R" 6 diodes
"P" 5 diodes

It makes it a very simple project that you can get to work with just a voltmeter, if that.

There might be some clever ways of reducing the number of diodes.

Hi Eric,

ericgibbs said:

Hi Torben,
I also agree with the old saying 'keep it simple', why over complicate a task.

Regards

Click to expand...

Maybe it's worth it if you're an unethical engineer getting kickbacks from the maintenance shop. I dunno because I also maintain all the software I write.
So I love keeping it simple if I can.

Then again, there's also this: "For every problem, there is a solution which is simple, elegant, and wrong" -H.L. Mencken. From that, I usually wind up back at Einstein's "Keep it as simple as possible, but no simpler".

I know those who've suggested microcontrollers to me and I replied with "I want to use TTL" must think this is out of character for me, but those instances are ones in which I'm after education as much as an implementation. When it just has to work I usually try to figure out what I am doing that doesn't need to be done.


Torben

hi Torben,
I know its a bit off topic, but here goes.

I use the old motto 'good enough is perfect' I suspect this gets up some peoples noses!..

What it really means, if the design solution meets the design specification/criteria and it gets the job done, there is no need for 'bells and whistles'.

Some engineers must imagine they are decorating a christmas tree, the jobs not done till theres a fairy on top!

If a guy/gal wants a complicated solution to problem as a learning exercise, thats OK by me.

ericgibbs said:

hi Torben,
I know its a bit off topic, but here goes.

I use the old motto 'good enough is perfect' I suspect this gets up some peoples noses!..

What it really means, if the design solution meets the design specification/criteria and it gets the job done, there is no need for 'bells and whistles'.

Some engineers must imagine they are decorating a christmas tree, the jobs not done till theres a fairy on top!

If a guy/gal wants a complicated solution to problem as a learning exercise, thats OK by me.

Click to expand...

I agree completely.

Now, would you please tell my boss that?


Torben

Here's a link to a very similar thread where the o/p wanted to display the gears on his motorcycle. This (my) arrangement uses a 7-seg led display, but could easily be modified to use a 16-seg led display and do what you want. A dot matrix display of any sort is going to be quite a bit more complex (requiring microcontrollers, etc.).
Jeff

*edit* this is basically what Diver300 described.

Hello to all and thanks for your comments.

I don't understand how to navigate this forum. This is the first time I have been
able to get to all the replies. At the other times I accessed the forum it appeared that no one replied to my post.

Anyway, I really am set on having a single character 16 segment display.
Because of the changed orientation of the shift mechanism in regard to the
console and dash, I can't readily use the old indicator strip. I also like to keep
things simple - "quick and dirty" is usually my motto. However, in this case I'd
like to try the Picaxe method suggested by dknguyen.

I checked my Helm manual for the vehicle involved (2006 grand prix, engine
and dash and wiring swapped to a '88 fiero) and found that the transmission
provides the pcm with the shift position by means of 4 coded lines. By configuring the Picaxe 28X to have 4 i/p's and 16 o/p's, I think I can get the shift position by splicing from these coded lines to the Picaxe i/p's and then program the o/p's to activate the segments for each character I want to display.

What do you think?

Orville

Should be fine, but it's really just a simple look-up table, you could use an EPROM to do the same thing - assuming you have access to an EPROM programmer?.