Need help with school project

Hi all,

I am currently working on a project for school. This project is to create turn signals that can go on the rear end of a bicycle, as well as having a thin light panel for nighttime riding. I would like the turn signals to have the following critera:

  • Two LED lights on one panel, with each "light" being an arrow that faces the opposite direction (just like a normal turn signal on a car)

  • Each light (right and left arrows) being controlled by their own activation mechanisms. Basically, one button to click that will wirelessly turn on the right LED blinker signal, and one button to turn on the left. These buttons would be separate from each other (not located on the same panel).

  • Pressing both buttons at the same time will make the LED arrows blink in unison (just like hazard lights on a car).

  • Holding each button for two seconds at the same time will make the LED arrows blink in unison even faster (like emergency lights).

  • A thin light panel that could be activated independent of the turn signals (again, wirelessly) so that the user can be seen by others at nighttime without activating their turn signals.

I read that something similar to this could be achieved using two HC-05 modules, with one being a "master" and the other a "slave". What this means is pressing a button on one of the modules will light up an LED on the other.

If someone could point me in what direction of how to get started with this and what specific materials would be best suited for this application it would be much appreciated!

It's not clear whether you have two of three boards in mind. It seems like there will be a board with the control switches and then either one or two boards for the rear lights.

Assuming there is only one board for all the rear lights (which would be much simpler) you will need a microprocessor and wireless for the control board and another for the lights board. They could be two Arduino nanos coupled with two Bluetooth HC05 modules. Another option would be to use two boards that have the ESP8266 chip (such as the Wemos D1) which combine a microprocessor and WiFi but for your project the ESP-NOW feature would probably be a lot simpler.

If you have three boards with 3 microprocessors than Bluetooth is not really suitable as it is a one-to-one system. The ESP8266 idea would work fine. Or you could use Arduino nanos with nRF24L01+ wireless modules.

The idea of holding buttons for 2 seconds may not be as attractive in practice as it is in theory. I reckon it would be very easy for the user to get it wrong and become frustrated.

...R

Hi Robin,

Thanks so much for your advice. After reading this, I definitely agree it could be simplified. I am now thinking that I could have two “activation switches”, and two light panels (each controlled by a separate activation switch). Would I be correct in saying that I would need two Arduino nanos, and two Bluetooth HC05 modules? And that each Arduino nano would control its own Bluetooth HC05 module? I have attached a screenshot of the concept I would like to achieve. Again, it is important to note that each light can be activated independent of each other. Thank you!

asthmadragon54: I am now thinking that I could have two "activation switches", and two light panels (each controlled by a separate activation switch). Would I be correct in saying that I would need two Arduino nanos, and two Bluetooth HC05 modules?

Thanks for the photo - it helps to visualize what you are doing.

I'm not clear how you have come to the idea that you need two nanos and two Bluetooth modules. At the very least it seems to me that you will have three boards - one with the switches (the transmitter) and a receiver for each for the two light units - I am assuming the wheel prevents you from running wires from one light unit to the other. If you could run wires between the light units then one "receiver" would do for both light units.

As I mentioned earlier if you have three boards I don't think Bluetooth would be practical.

...R

You would be correct in assuming the wheel prevents me from running wires. That is why I'm trying to complete this wirelessly.

The three board idea definitely would be the most practical. However, I am trying to create something that does not currently exist. So far there are currently existing bicycle turn signals that you are describing (one transmitter that can control two lights). Because of this, I am trying to create two light units that each have their own switch / wireless transmitters. Would bluetooth still be a poor approach to this?

asthmadragon54: Because of this, I am trying to create two light units that each have their own switch / wireless transmitters. Would bluetooth still be a poor approach to this?

I think it will make the discussing easier to follow if you give names to the devices. Based on the piece I have just quoted I think what you have in mind is as follows

  • TransmitterA sends to LightUnitB
  • TranmsitterC sends to LightUnitD

If that is what you want to do then you would need 4 nanos and 4 Bluetooth modules and, yes, it would work with Bluetooth because each would be a simple pair.

However if this was my project I would have one nano for the switch unit (both switches) and one nano for each of the light units and I would use nRF4L01+ wireless modules rather than Bluetooth. Or you could use three ESP8266 devices (perhaps Wemos D1 units) one for the transmitter (both switches) and one for each of the light units. With the ESP8266 there would be no need for any nanos or any separate wireless modules.

...R

I have to create something that doesn't exist already, so unfortunately I don't think the three board approach is viable (as it is imperative that I have the scenario you described, with Transmitter A to LightUnit B, and Transmitter C to LightUnitD). Would this be possible to achieve with a wireless module such as an nRF4L01+? If not, I might have to go with the 4 nano and 4 bluetooth module.

Spend some time thinking about how many batteries you will need for this project and how much capacity each will need.

Paul

asthmadragon54: Would this be possible to achieve with a wireless module such as an nRF4L01+? If not, I might have to go with the 4 nano and 4 bluetooth module.

Either would be possible.

...R