I continue a series of notes about homemade (DIY – do it yourself) timing for skiing with Arduino. In this note I will maintain information about the main electronic modules. Arduino is something like a radio kit, so the modules are designed to be electronically compatible, and you can “match” them without using a soldering iron. However, I admit that not everything will be smooth. The Internet allows you to edit a note at any time, so in the end there will be cool information enough to repeat the project 🙂
In the first article, “Timing system for Alpine ski based on Arduino. Task formulation”, the flowchart of “omega” and the general idea of “playing around” with Arduino was examined. I hope that modern means can make omega on the radio channel without having radio skills.
In the three blocks (starting, finishing and base) there will be the same modules: the Arduino nano microcomputer, the radio channel module and the power supply on 18650 lithium-ion batteries.
Arduino Nano 3.0 on the ATmega328 chip. By the way, working temperature: -40 +85 С! The price (on Ali-Express, hereinafter – with delivery to Russia, recalculated from rubles to USD) is $3.30.
Radio module NRF24L01 + PA + LNA. that is, the “regular” NRF24L01+, popular among the “Arduiners” for wireless communication of up to 6 devices on the Arduino, but supplemented by an amplifier and antenna. The module operates at 2.4 GHz and, in general, is a part of the “standard” radio with the ability to work on different channels. The range should be about a kilometer. In principle, if this module is not enough, then you can order more powerful ones, on more modern communication standards. But I would like to stay on this module, since it is very well run-in by arduiners. The price is $1.81.
This module needs a power supply matching unit, which is purchased separately. Price – $0.62.
For power supply chose batteries 18650 with already attached wires. Such batteries could be with a high discharge current (it seems that they have appeared recently) for designing the replacement of batteries with all kinds of screwdrivers. As I understand, these batteries are made in brown color. I need regular, low-current, that is, any other color 🙂 A battery needs a charger unit (Micro USB 5V 1A 18650 TP4056 name) and a voltage boosting block up to 5 Volts for Arduino or up to 12 volts for the photo finish (the module is called MT3608 DC- DC Step Up Converter Booster). So far I intend to do with one battery in each device. But if it is not enough for 3 hours of work in the cold, then you can simply connect in parallel more and more, without changing the circuit design. Price: Battery 164 $2.50, charge $0.34, voltage converter $0.41.
In the base unit, which will be connected via radio to the Start and Finish, the time indicators for three participants are added to the above modules. That is, three such indicators measuring 42×24 mm (this size was specified when ordering). In fact, this is more likely a board size (40×22 mm), and the size of the indicator itself is 30×14 mm.
The name TM1637, price $0.59 apiece.
Here are all the basic electronic components for the three devices: the Start, the Finish, and the Base unit. The total cost with delivery is $28.74. Of course there are still small things: buttons, LEDs (sold by bags, and not by the piece), a couple of buzzers at the start and finish, but this does not significantly change the costs. In addition, since I made a large order from one supplier, a noticeable discount was calculated before payment. For example, the module Arduino in fact cost $2.44 when ordering 5 pcs.
Ordered such garage sensor (retro-reflective photocell). In the description, the range is 4 meters. This may not be enough, but more powerful options are not liked, including the price.
The name of the sensor is LPSECURITY 4 meters, the price is $16.28.
LPSECURITY is the name of the seller. The name of the sensor is E3JK-R4M2. On the sensor that is delivered, the manufacturer specified Omron. Fast punching via the Internet showed that Omron discontinued these sensors in 2015. On Ali, the E3JK sensors are now the most common. I think that this is a typical OEM, since the manufacturers indicated on the sensors can be very different.
The “Start”, “Finish” and “Time board” units as a result consist of the following modules. Details in the relevant individual notes, which can be reached through the table of contents.
In addition to the main blocks, the ability to connect individual stopwatches is added in case the range of the main radio channel is fundamentally not enough. Short-range transmitters are added to the Start and Finish, and a stopwatch with a short-range receiver is in skier pocket. Such stopwatches could me many.
How these modules are connected can be found here: Timing system for Alpine skiing based on Arduino. Connection Diagrams.
Here are collected all the notes on the theme “DIY timing system for skiing with Arduino”.