Make your own speedometer
Today, well into the 21st century, practically every vehicle comes with its own speedometer and odometer. This is true for cars, motorcycles, some e-bikes, and so on. Furthermore, there are also many apps in the various app stores that allow us to know our speed and distance using the mobile device's GPS. But what's the problem with these apps? They run on a device that isn't always the most affordable. As with almost everything, one solution to the problem could be to create our own speedometer.
Everyone knows how much an iPhone costs. I personally own one, and for months I was afraid of falling off my bike, more for my phone than for myself. Now I use a Garmin, but any device from this brand costs hundreds of euros, something many users can't or don't want to spend. If we know what we're doing, sometimes the best option is to build our own hardware, and in this article, we'll show you how to build your own odometer from scratch .
Speedometer and odometer for bicycles
Requirements
To mount our speedometer we will need:
- Arduino UNO & Genuine 1 (No products found.).
- 1 Adafruit RGB Blacklight LCD - 16 × 2 (No products found.).
- 2 SparkFun 12mm Pushbutton Switches No products found..
- 1 221 ohm resistor (buy).
- 3 10k ohm resistors (buy).
- 1 10k ohm single turn potentiometer (buy).
- 1 Hall effect sensor (buy).
- Hands, time and patience.
Who is this tutorial for?
As we mentioned earlier, nowadays virtually every phone on the market has GPS and an app like Runtastic or Strava. Personally, I wouldn't recommend this tutorial to anyone who already has a smartphone, unless they want to create their own speedometer. Well, that and making sure they don't break their phone in an accident.
This tutorial is also for those who already own an Arduino Starter Kit for another reason and don't want to spend the money on a basic cycling computer . This speedometer will cost just over €30, so this tutorial is aimed at people who don't want to spend a lot of money and want to build their own odometer.
What are we going to manufacture
What we are going to manufacture is an odometer and speedometer for bikes that will tell us:
- Distance traveled in kilometers.
- Activity time in hours, minutes and seconds.
- Average speed in km / h.
- Maximum speed achieved.
- Ability to record up to 99 laps.
How to use this full-featured speedometer
Speedometer circuits
Once our bicycle speedometer is finished, we can turn it on. The first time we turn it on or reset it, a message with the text "PRESS BUTTON TO START" will appear on the 16x2 LCD screen. Pressing one of the Pause/Resume or Display Mode buttons will start the first period/lap.
The next thing we will see is a message that says "CYCLE SAFELY!" (circulate carefully) for 2 seconds, but in that time interval it is already recording. When the message disappears we will be able to see the kilometers traveled, the speed next to the "S" (for "Speed"), the time already consumed in the second line and the average next to the "A" (for "Average") .
All the information is displayed in real time . This is relatively important considering that the mobile apps I mentioned earlier calculate distance using GPS, so it's not displayed in real time. The difference is that, without a sensor on the wheel, mobile devices show the speed fluctuating, while this device displays the values ​​gradually, like in a car. The sensors mentioned must be Bluetooth-enabled and compatible with the mobile device. And buying them separately is usually not very cheap.
Displays information in its 4 corners
The "+" symbol will appear in the upper left corner for 250ms when a wheel revolution is detected. Pressing the Display Mode button will change the "A" on the second line to "M", showing the maximum speed achieved so far in that revolution/period.
Pressing the Pause/Resume button will stop recording and save the current lap to memory. The message "PAUSE!" will then appear for 2 seconds, and the results of the completed lap will be displayed with the lap number in the upper left corner of the screen, followed by "Avg" showing the average speed for the entire lap and "Max" for the maximum speed of the run. The second line will show the distance in kilometers followed by the lap time in hours, minutes, and seconds.
Capable of saving up to 99 laps
Electronic diagram of the Speedometer (Click to enlarge).If you press the Display Mode button while the device is paused, it will cycle through the recorded laps . The first time you press it, it will show your best lap with a "T" in the upper left corner, while subsequent presses will cycle through lap 1, 2, 3, etc., depending on how many laps you have recorded.
If you press the Pause button again, it will start recording a new lap, displaying the message again that tells you to cycle carefully. If you press the Pause button again while seeing the message "CYCLE SAFELY!", no lap will be recorded , and the device will return to pause mode, displaying the data from the last lap you completed.
This speedometer can record 99 laps . If you reach lap number 100, the remaining data will be overwritten with lap 99. However, any records achieved during your activity will remain even if the data from lap 99 is erased. In other words, if you set your record on lap 99 and then complete a 100th lap, only the average speed and distance data from lap 99 will be erased; the maximum speed will be retained.
In the following video, you can see how this bicycle speedometer works. You can download the software code by clicking on THIS LINK , and you can download the schematic by right-clicking and saving the image from your browser.