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Topic: Feasibility: Replace Older Motorcycle Dash with LCD? (Read 21023 times) previous topic - next topic


Jun 15, 2011, 03:09 am Last Edit: Jun 18, 2011, 02:44 am by 2Wheeler Reason: 1
It's my first post, and I have been doing a lot of reading & searching. I found this forum after reading about some quasi-similar projects with an Arduino. Here's my situation:

I have a mid 80's Honda Sabre motorcycle, and the gauge panel is severely broken. I was able to salvage everything except the speedometer. The parts for it are no longer available, and used parts are sky high in cost when available, plus they're 25 years old. The bike uses an electronic speedometer & tachometer, along with a digital display that had LCD gear positions (via 7 wires- one for each gear and neutral), fuel level, and water temperature. The bike predates the engine control modules and data bus setups of newer bikes- it's fairly old school. The wheel speed sensor uses a three wire setup: an 8V input from the dash, sensor ground, and outputs 0~4 to 8V back to the gauge per the shop manual. I've looked at late model bike dashes, and many use CAN BUS setups that I'm unfamiliar with. Some older ones still uses similar sensor data as what mine does, so they are a possibility, but I'd have to add-on gauges to monitor all the things I want to monitor. I've looked at dashes (via wiring diagrams & shop manuals) from all the Japanese models as well as Aprilia, Buell, Ducati, and Triumph and even a couple of snowmobiles. All are either lacking a feature I want or they cost way too much. What I'd like to do is hijack a later model dash with an LCD panel & make it display the stuff I want... but I digress.

I found some LCDs with built-in serial graphics here. I downloaded the software tool and have been learning how to use it. Of course, I'd need either a waterproof LCD or secure casing for it/them. I have a basic understanding of electronics, and the ability to learn about things- I've self-taught myself things such as welding and AC repair.

I'd like to build an Arduino project to drive an LCD (or possibly 2, speed & RPM). What I'm planning to monitor is as follows, along with my comments:

  • Road speed (from original wheel sensor)

  • Engine RPM (currently uses pulse from coil, would likely need a frequency to voltage converter from what I've read)

  • Water temp

  • Fuel level- would like this to be a bar gauge, but could use percent, and want it to display the words LOW FUEL at a certain level

  • Oil temp

  • Oil pressure

  • System volts

  • Air temp- would display "ICE" below 35 degrees

I'm familiar with modern automotive transducers that operate on 5V & output 0~5V, it seems like this would be a good way to go for some of these inputs.

I'd also have indicators/warning functions, all were part of the original dash:

  • High beam

  • Gear position & N for neutral

  • Tail light circuit failure

  • Low oil pressure

I don't need fancy displays on the LCD, just numbers & letters. I drew a prototype using some software and have attached a JPG of what I'd like to end up with (single screen).

Is this a feasible project or would I be better off trying to adapt a later model dash panel to my bike?

Thanks for any advice. I have a lot to learn & look forward to doing so here.


Thanks for the reply. The bike runs on a 12V negative ground system, it's a 4 cylinder 4 stroke.

I have found a supplier for the 138 x 105 display size 320x240 resolution amber LCD from Electronic Assembly. It's about $222. I'm wondering if this resolution is overkill. I can find a black & white display that is larger but with lower resolution for under $90 at the same supplier. I can squeeze all my info onto the 138x105 size screen if need be.

I know there is an enclosure for the Arduino, but where would I find these for the display? Is this usually a custom-fabricated part? Most of the bike projects I see kind of have everything hanging out. I plan on putting the Arduino in the back of the bike under the seat, and running an interface cable to the handlebars. If this is not practical, I could locate the enclosure behind the display.


Jun 15, 2011, 01:46 pm Last Edit: Jun 15, 2011, 01:48 pm by Korman Reason: 1
I can't really help you with the inputs, you best have a look at them with an oscilloscope. Give the age, I would guess that you're getting some kind of pulses relative to the speed or rpm, but on;y testing will tell. If this is the case, you can build this with an Arduino quite easily, that won't be the big challenge.

In my opinion, what will turn out to be a problem is the environment. First, I would put the Arduino in the same enclose that the display. Mounting it somewhere else will only add cabling to your solution and potential entries for water. If the Arduino itself is too big and you don't want to make a custom board with the Arduino included, get an Arduino Mini Pro.

The next challenge will be vibration. I guess, forget the pin contacts, they will work loose. Soldering is the way to go, which brings us back to the Mini Pro.

Then your enclose: It's going to be exposes to rain, cold, heat, sun, vibrations and water from the garden hose if you ever wash your bike. The enclose needs to be sealed. I haven't seen yet any commercial enclosures made for the Arduino which can withstand in such an environment. You should primarily look for an enclose to work in that environment and see if you can fit an Arduino with the display inside. My best guess would be the junk-yard to see if you find an old motorcycle speedometer to cannibalise.

About the display itself, make sure you find one that withstands the vibrations and the sun and also is still readable in bright sunlight from behind your back and at night.

And last, you should check whether your bike is still street-legal with the new display. Here in Germany, you need to have at least a certified odometer and speedometer otherwise you'll fail the yearly inspection.



Take a look at this.

The LCD would probably not be brilliantly visible in bright sunlight but it might give you some ideas. It is an OLED display though so it will be more visible than a typical TFT LCD screen.

Interface cable will probably work fine but it depends on the length and what it passes by - you might have issues.

Enclosures are typically custom made for projects like this - 3D printing is quite expensive but sometimes this can be justified as it creates exactly what you want and if you were considering $222 for the display, a 3D printed case is possibly not out of your price range.


Thank you both for the replies. As it turns out, a member of the bike forum I'm on has an Arduino and is working on coding to do much the same thing I am. I agree it would be best to have everything in one box behind the display. On the scooter project page (excellent page for a new person like me to see how this actually works), he has all of his links. I looked at the box enclosure page and they have IP65 sealed boxes with clear lids. They go fairly large, like 5.7 x 7.3 x 2.9 (147x188x75) for $25, so it looks like everything would fit in there. I think my ideal LCD size based on the gauge panel on the bike is around 180x102.

I will do some more looking around- that scooter project sure evolved into a lot more than a battery meter, and I'm sure it's very easy to fall into the "while I'm at it" trap of doing a lot more than you had planned.

The price point for this at fist seemed to be a problem. I can pick up a used set of gauges w/ LCD panel from a newer model Honda for under $300, but they will lack several functions such as oil pressure, oil temperature, and volt meter. Plus they apparently require a $100 calibration device for the speedometer (although I could probably figure this out for less based on shop manual data). All told, I'm looking at adding up to $200 worth of extra gauges and parts. The main expense for this project would be the LCD. I don't want to skimp on it, as I know how tough they can be to see in sunlight here in Florida. I have an Archos 5 tablet PC I use as a GPS on the bike & it's impossible to see on bright days, and this is the environment I'm usually in for riding.

The key to using one of those enclosures would be mounting the LCD so as to protect as much as possible from vibration. I'd have to find a good material to mount it in to do so. I could run wiring to the bike out the bottom via a boot, so the elements would not get in. Once I saw where the LCD was to be mounted, I could mask off the display area and use some paint to cover the clear parts. The gauge bracket on the bike would be a natural fit for a box- it has a flat plate with 4 rubber bushings to mount the original panel.

Thanks again, I'll keep looking into this.


For vibration - you can get various silicone/silicone coated mounting hardware for various things but I wouldn't have thought vibration would be a major issue. Just have to make sure components are securely attached to any boards - normally just solder them close and tack them with hot glue for support which seems to work very well.

I look forward to hearing about what you end up doing


Regarding the LCD - you're looking for a transreflective LCD - datasheets will normally tell you what the contrast is like and give a rough idea of which is better in bright sunlight.


Jun 15, 2011, 03:14 pm Last Edit: Jun 15, 2011, 03:40 pm by 2Wheeler Reason: 1
Thank you. I found a Hantronix HDA700L-1 TFT that is 152x91 for viewing area for $116. The datasheet says it has a 250:1 contrast with a brightness of 500 cd/m2, and a resolution of 800x480. Apparently it is made for in-car TV and DVD players, so it may not be bright enough (still learning what the cd/m2 is as compared to other units). I could not find if it was transreflective or otherwise.

I found data for my too-dim Archos. It is 339 cd/m2, so 500 would be better. I found a transmissive Optrex 8.4" display rated at 1200 cd/m2, but I can't find a single unit purchase site (minimum order of 20 @ $396 ea).


You may have seen my project in your googling http://arduino.cc/forum/index.php/topic,8474.0.html - I'm still playing with it. 

I'll give you a few random thoughts:

  • Packaging the LCD to be waterproof proved to be too difficult for me - i'm still looking for a solution

  • I ended up using a simple set of LEDs in a homebrew bar-mount because they were easy to waterproof

  • Hardening the arduino power supply to survive the bike's 12V environment is a significant challenge

  • I did not attempt to combine everything in one package because all my sensor access points were in a tank mounted console and i wanted my display on the bars

  • Each input you want to deal with at 12V means several components to protect the arduino and more leads to connect so if some things are ready to drive LEDs or idiot lights on their own I would just do it that way

  • One of the good decisions I made was to make sure I had serial access to the cpu for debugging and reprogramming.  I also hooked up a bluetooth module to get in-flight data

Pics below: Failed waterproof LCD enclosure; Bicycle speedo as a waterproof display; Bar mounted LEDs.

Also, here's a fellow using a Nokia tablet for his display and a ram-mount box to protect it.http://forum.sparkfun.com/viewtopic.php?p=80410#80410

Good luck and keep posting!  I actually have several of the prototypes around and if a circuit or the physical board would be a big help, PM me.


Thanks Bill, your thread was one of may I read about. If you haven't been able to waterproof the LCD, that's bad news for me. The box I'm looking at is here:

It looks like there is a casting mark in the center, which would not do much for the use of the LCD behind it.

One thing I'm running into is the display brightness. Most seem to be in the 200~300 range, a few @ 500 and in the 8.4" range (probably larger than I'd go) 800 and one at 1200 (minimum order of 100 @ $396 ea). Since I have real world experience with my Archos 4.8" LCD @330, I know it needs to be a lot brighter than that. From what I've read, to be sunlight (vs daylight) readable, they must be rated at around 1000 cd/m2 or better. I've found some high-end displays that are rated as IP65 or better for moisture, but haven't seen any prices. I suspect it's one of those if you have to ask the price...

I don't want to go to all of this trouble & expense only to have something I can't see during the day. I suspect the best thing for my situation is to either make a hybrid of the warning lights & LCD panel (those were undamaged in the crash) and add in some aftermarket gauges to fulfill the other functions, or use a later model panel.


As I mentioned - you probably want a black/white (single colour) transreflective graphic LCD with backlight that you can automatically adjust depending on ambient light level (although as it's being powered with the bike battery, this probably isn't necessary as the backlight only really needs to be turned off for battery powered devices.

Transreflective LCDs, although not as good as e-paper displays, are easily sunlight readable.


I will look for what you suggested, as well as a better enclosure. I found one at Overstock.com for a PSP that is $16.87 and has dimensions of 1.9 in. x 7.3 in. x 3.875 in. Not sure if it's watertight, but it is aluminum and it has a clear window. Too small for what I want to do, but maybe it could work for another project. I think I may be able to find a better quality NEMA enclosure for my project.

I have priced out used parts for several variations for the gauges on my bike. I'm looking at anywhere from $250~400 to go that route. If I can find a sunlight viewable LCD for a decent price, I can go this route for less money.

I have been watching how-to videos and beginner stuff for the Arduino, and this brings me to my next research area. I see there are numerous variations of it, nano, mini, mega, etc. Keeping in mind my above requirements: monitoring speed, RPM, voltage,temp x3, gear position (via 7 wires), and pressure plus a clock function, which board is best for me? I was planning on buying one of the starter kits & learning hands on how to do stuff, but would like some advice before doing so. As I understand this stuff, my biggest expense is going to be the LCD, followed by the Arduino. Am I missing anything? I know there will be a lot of other stuff such as transducers & frequency converters, but I'm just looking at the basic system for right now.

I'm also of the opinion if someone made a simple gauge panel that could easily be adapted to bikes, it may have some market appeal. There just isn't anything like it on the market now- at least not under $650 or so.


Jun 16, 2011, 07:18 am Last Edit: Jun 16, 2011, 07:24 am by Korman Reason: 1
For your needs, I would suggest either the Pro Mini together with a FTDI USB-Breakout cable or FTDI USB Breakout board or the Arduino Nano. Those have the smallest form factor and don't have any connectors soldered on. Those are best for use on your motorbike. To use the Pro Mini with the breakout board, just solder pins to the serial and you're ready to go. My development kit with the Pro Mini looks like this:

About the starter kits, I would forgo those, as you have a very clear project in mind. Just get the parts you need, a breadboard and your usual collection of resistors, LED buttons etc. But I guess, you have those anyway. In this project, as written above, the real challenge is the electrical part to get stable and clean power and the enclosure.



Thank you Korman, I will look at those.

I sent an inquiry to a Chinese company on Alibaba about 7" and 8.4" LCDs that were supposed to be sunlight viewable. I got two datasheets back. I'll attach the 7" one (400K)- it is a customer acceptance form, not really a datasheet, but is 24 pages of info. It appears to be from 2003.
It's listed as being transmissive.
Brightness in cd/m2: min 800, typical 900, max 1000.
Contrast ratio seems low: min 100 typical 200 and max 2) (typo?).
The lamp voltage seems a lot higher than others: min 9.3, max 10.8.

I was quoted $120 for the sample, and for a run of 100, $95 each. The display area is 152 x 91, which is a good fit for my project.

The 8.4" unit's datasheet was from 2010. it did not specify transmissive or transreflective.  It looked to have better specs:
Brightness in cd/m2: min 900 typical 1000  max -(none listed)
Contrast ratio: min - typical 600  max -
Input volts: 3.3

It is $260 for the sample, and the display area is 170 x 128. Overall, it is 203 x 142. When I scaled out the overall size, I could fit this on my bike, as it's narrower and only a little taller than my original gauges. I've attached a 1:1 scale drawing of the 8.4" unit with my proposed layout. The nice thing about a larger screen is the larger fonts. My drawing program goes to 127 points, which is about 1.76". I used this for the speed & RPM numbers. Most of the other numbers are 36 point, or 1/2".


About your design: Numeric rpm is really bad user interface and annoying. For rpm go with a bar or gauge at the side of the display, that's far easier to parse while riding.


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