In the line of single-board computers Arduino “Nano” is a miniaturized “classic” board “Uno” with the same number of I/Os and the ability to work through the USB port. Unfortunately, in addition to miniaturization, simplifications were made. Among them are two that are not associated with a decrease in size. First, the replacement of quartz on ceramic. Secondly, the removal of the “normal” power 3.3 volts. The remaining leg 3V3 is supplied with weak power from the controller serving the USB port.
On Ali-Express, Arduino Nano clones are mainly sold according to the principle “as it was intended”. But among them there is a development (of course more expensive) from the company RobotDyn, in which normal quartz and normal supply of 3.3 volts were “returned”.
In the timekeeping system for alpine skiing it makes sense to put such a version of the Arduino Nano in the “Start” and “Finish” units. In this article I will briefly describe Arduino Nano from RobotDyn.
From my point of view, the classic Arduino Nano single board computer is neither bad nor good. It has a rather weak processor and little memory. This affects if you need to drive the graphics on the monitor from the smartphone. For tasks like “timekeeping for skiing”, processor and memory performance is more than enough.
Quartz sets the clock frequency, which determines including the calculation of time intervals in the program. Timing is determined by reading the internal timer, which starts when the program is turned on. The difference between the two specific Arduin Nano’s timers used in the Start and Finish units was 99.79%. That is, if you synchronize the clock, for example, before training, then in an hour the difference will be 8 seconds. This is certainly not good if you do a “real” stopwatch. But in the adopted logic of the implementation of timing, this difference is not at all critical. Yes, and programmatically adjusted. In general, compact ceramic quartz in the “classic” Arduino Nano is also “neither good nor bad”. However, it is not yet known how such quartz will work in the cold.
Finally, the lack of a powerful 3.3 volt stabilized power supply is, if necessary, adjusted by a separate module. Such a need arises when working in general with any radio modules, because for some reason the 3.3 V power standard is adopted there.
I had to turn to Arduino Nano from RobotDyn in the process of finding a solution to the problem of the normal operation of the radio modules. The fact is that specially purchased adapters for radio modules, which consist of matching connectors and a 3.3 V power converter of five volts, did not pull the load during data transfer. Read more here: Timing system for Alpine skiing based on Arduino. Radio channel on modules nRF24L01+. Therefore, it was necessary to order other modules “at random”, whether they would be suitable for sure. And “to the heap” order two Arduino Nano from RobotDyn, because there the 3.3 V module is already on board.
Arduinos arrived the very first, the problem with the transfer of data was solved. Delivery time is really impressive, 18 days. The price, however, is also $ 4.71 including shipping. Let me remind you that the “ordinary” Arudins Nano cost $ 2.45, the delivery time is 25 days as part of a large order. True, you probably need to compare with the additional cost of the power adapter ($ 0.42 and 39 days, the one on the top of the photo, or $ 1.09 and 36 days, those that ordered instead, and now are not needed).
Put these Arduinos only to the Start and Finish units. In the “Timeboard” unit, the radio module and adapter worked normally, because it was solely as a receiver. As a bonus, I received the running timers at the Start and Finish in the same speed (within the project requirements), so I threw out the coordinating procedure from the program 🙂
I will list the differences between Arduina Nano and RobotDyn from the “classical” one.
- Other USB connector.
- Visually, there are much more elements in the power modules.
- Gilded (in appearance) legs.
- Quartz, larger in size and better in performance.
- A more powerful 5 volt power supply module (I don’t use it).
- Quite a powerful 3.3 volt power supply module (500 mA). In the “classic” Arduino Nano, the declared maximum current on a 3.3-volt leg is only 20 milliamperes (that is, probably enough only to measure it with a tester).
Here are collected all the notes on the theme “Timing for skiing on Arduino”.