Arduino + two servos + charging board + boost converter board + old battery + a bunch of radio components + piece of plywood + toggle switch = an idiot's dream come true!
Lots of text for those who like to read. Lots of spoilers for those who like to read diagonally. Video, for those who love videos. Sketch for those who like to immediately copy and run “on the knee”. Photo, photo, photo. Cat, for cat lovers.

Not really a disclaimer

This is my first project, apart from blinking LED, Hello world, etc. According to tradition, you must first sprinkle ashes on your head to ensure that the code is far from perfect and be sure to get involved in a dispute about this. And also regarding the partial copying of code from another project, ask not to hit too hard, etc. But this won't happen. The code is perfect! Because it works, I like it and I made it for myself.
I’ll give advice to those who are interested: don’t be afraid, join the battle, shovel mountains of code, build your own mega-pyramids from different operators. Over time, style, sophistication, and ideal will come.
As long as there is space in the controller's memory, you are not afraid of anything. If you hit a wall, you will optimize. And this is also development. It's important.
A big book on C programming - yes, useful. But, at first, it is much more useful to have a quick reference guide on commands at hand and keep in your bookmarks several links to working with simple examples, libraries, etc., like, or the same Ampere.
Also, flowcharts help me a lot. Rectangle, diamond, oval. Anyone who has encountered it understands. I'm doing one project now - I can't do it without a flowchart. For me, it’s better to draw for several days - redraw on paper in order to more clearly imagine the entire flow of the program, than to jot down a bunch of code and get stuck in it, because... I do not have the ability to cover the entire code with the power of my programming thoughts, due to my limited experience.
For those who want to repeat it or do it their own way, I will answer all questions.
I will not enter into empty disputes about my writing, style, design, code and necessity of the product, etc. If I made a serious mistake somewhere in the review, I’ll correct it or add it.

You can Google what “The Most Useless Device” is. I came across it by accident. This code was taken as a basis, because it didn’t launch on its own, and I wanted to make my own scripts.

Lyrical digression

They say that after forty, especially when you are already very much after forty, you need to try to “flex” your brain. And that learning languages ​​is the best warm-up. And not only at that age. I'm not very good at languages, but the Health magazine seems to advise... In general, I decided to learn something new for myself. Electronics is not new to me, although I have forgotten most of it, but programming has never been familiar to me. I was afraid of him. But here many signs from above coincided: the magazine “Health”, which recommends learning something new, a long-standing dream to understand (at least a little) programming (at least something) and youtube, in which only the lazy do not talk about how to blink an LED using smart fee for a dollar and a penny.
Before this, I managed the LED blinking pretty well using two transistors, a capacitor and a pair of resistors, but now, they say, it’s not comme il faut. So you need to be in trend.

I really liked this useless, in the literal sense of the word, device. I saw it and fell in love. I want it, that’s all! Like a child's dream! But age has made its own adjustments. I want to make it myself, not buy it. Especially since it's on sale simple devices. I came across an “intellectual” one, but I couldn’t find anything like it on sale. Moreover, it must be done!
And again, Arduino. And I don’t boom-boom in it. So we need to figure it out. Aliexpress to the rescue. I started with Arduino. I understood that the path to study would be thorny and sacrifices were inevitable. So I ordered five different ones. Let them burn, if anything. Debugging of the circuit took place on Uno from another seller. But, since this particular board was in the final device, it was included in the title.
In addition to Arduinos, I ordered a huge amount of all kinds of junk, both Arduino-compatible and near-Arduino. Here I will only tell you about what was useful in this product.

Arduino Pro Mini

Delivery is fast, packaged in a standard antistatic bag and envelope with a pimpled inner surface. The seller is sociable, Russian-speaking.
On a 328 chip. 3.3 volts, 8 MHz. Why is this so? Yes, by mistake. I wanted 5 volts, 16 MHz, but bought this one. It's my own fault. However, for this project it is not critical - I installed an extra voltage converter. That's all. I didn't find any huge differences from other Minis. The brand difference is black textolite(?). Of the jambs: the RAW pin does not work on the board. But that didn’t stop either. Although, a 3.3 V converter could save money with it. The combs are not soldered. The board is made well.
Why so short? Because there is already bias about this seller and his fees (clause 18). Those who want can find it easily. There is no point in retelling it. I also added my two cents in the comments to it. And I corresponded with the seller a lot.

Servo drive SG90

$3.2 per lot of two pieces.
There is nothing special to describe. Weak servo drive with average positioning accuracy, which is highly dependent on the speed of movement. But it's cheap. For the lid drive - more than enough, for the “hand” - on the verge of possibilities. It requires 5 volts to operate, but 3.3 is sufficient for control. I tried to control it through the converter and directly from the Arduino - there is no difference. Therefore, the level converter saved money.

Charge controller and power converter

$2.28 for five pieces. With protection. While charging, the red LED is on; when charging is complete, the blue LED is on. There was a review here.


$0.50 each. Delivery, however, is paid, but I bought a whole bunch of other things from this store, so delivery was not annoying. The USB socket was removed to lighten the weight))) The output produces 5.12 volts.

I took it offline. A little tight. To facilitate the operation of the servo, it was possible to disassemble it, shorten the spring or replace it with a weaker one. But laziness won. I put it like this. True, I had to write in the code additives to the angle of rotation of the servo at high speeds.

TTL converter

$1.5 per piece. Actually, I ordered it first. It's half the price. But, for some strange reasons, he died a heroic death. I still don’t understand how I killed him. For this reason, the project stalled for a month until a new, more advanced one arrived - no need to press reset. Isn't this progress?

The rest is from storage

Voltage regulator 1117T-3.3V in TO220 housing, capacitors 1500.0x6.3 and 470.0x16, two 0.1 μF capacitors, white LED and microswitch from a children's car, 220 Ohm resistor. The battery had been lying around unused for several years. I once took apart a burnt (literally) portable DVD player. The only good thing there was the batteries that survived. Here is one of them that came in handy. Voltage 3.7 V, I didn’t find the capacity in the labeling.
Glue gun, elastic band for money, two hooks from... a bra (thanks to my wife. Darling, I love you!), two furniture dowels, four screws, four adhesive bumpers for furniture doors, a piece of a breadboard, wires, connectors.

Simply put, great

At school we had a Trudovik. Aged. In general, he is a wonderful person. He was respected. When we went through electricity, using the example of a battery, a light bulb and a key, he gave us a lecture.
“There is current in the battery. Now he comes out of the positive and follows the wires. It goes, goes, suddenly bam - the key is on the way. And the key is open. Tok understands that there is nowhere to go further. He turned around and went into the battery. And the light doesn't light up. We close the key. The current started flowing again, reached the key, passed through it, passed through the light bulb and returned to the battery. And the light bulb is lit, frankly speaking, perfectly.” Since then, there has been such a phrase in the lexicon, as a synonym for something unexpectedly successful.

#include #include Servo doorServo; //cover servo drive Servo handServo; //arm servo Bounce bouncer = Bounce(12, 40); //create an instance of the Bounce class for pin 12 of the toggle switch int pos = 0; //starting position variable int pos1door = 70; //initial position of the lid servo int pos2door = 30; //final position of the cover servo int pos1hand = 10; //initial position of the hand servo int pos2hand = 160; //final position of the arm servo int r; //random number on which the option to turn off the toggle switch depends #define LED_PIN 11 // number of the output connected to the LED int ledState = LOW; // set the state of the LED with this variable long previousMillis = 0; // store the time of the last switching of the LED #define INTERVAL 30UL // interval between turning the LED on/off void setup() ( pinMode(LED_PIN, OUTPUT); pinMode(12, INPUT); // switch pin 12 to input mode digitalWrite(12, 1); //turn on the pull-up resistor on it Serial.begin(9600); //set the port to a speed of 9600 bps. For debugging. Then you can remove it. doorServo.attach(9); //assign the lid servo to pin 9 handServo.attach(10); //assign the hand servo to pin 10 doorServo.write(pos1door); //set the lid servo to the initial position handServo.write(pos1hand); //set the hand servo to the initial position ) void loop() ( if (bouncer.update()) ( if (bouncer.read()==0) ( //if the button is pressed ( r = random(0,11); //generate a random number jn 0 to 10 Serial.println® ; if (r == 0) ( move_0(); ) //call the function using a random number else if (r == 1) ( move_1(); ) else if (r == 2) ( move_2(); ) else if (r == 3) ( move_3(); ) else if (r == 4) ( move_4(); ) else if (r == 5) ( move_5(); ) else if (r == 6) ( move_0(); ) else if (r == 7) ( move_1(); ) else if (r == 8 ) ( move_4(); ) else if (r == 9) ( move_3(); ) else if (r == 10) ( move_0(); ) ) ) ) // Function library. General principle: open the lid - stick out your hand and turn off the toggle switch - remove your hand - close the lid // and there are options for how to decorate it beautifully............ void move_0())( //simple option: opened-turned-closed //open the lid for(pos = pos1door; pos >= pos2door; pos -=3) ( doorServo.write(pos); delay(15); ) //stick out your hand for(pos = pos1hand; pos<= pos2hand; pos +=3) { handServo.write(pos); delay(15); } //убираем руку for(pos = pos2hand; pos >= pos1hand; pos -=3) ( handServo.write(pos); delay(15); ) //close the lid for(pos = pos2door; pos<= pos1door; pos +=3) { doorServo.write(pos); delay(15); } } void move_1(){ //простой вариант 2: открыли-выключили-закрыли //открываем крышку for(pos = pos1door; pos >= pos2door; pos -=1) ( doorServo.write(pos); delay(15); ) delay(1000); //stick out your hand for(pos = pos1hand; pos<= pos2hand; pos +=1) { handServo.write(pos); delay(15); } //убираем руку for(pos = pos2hand; pos > <= pos1door; pos +=5) { doorServo.write(pos); delay(15); } } void move_2(){ //задумчивый вариант 2: приоткрыли-закрыли-открыли-выключили-закрыли //открываем крышку for(pos = pos1door; pos >= pos2door+15; pos -=5) ( doorServo.write(pos); delay(15); ) delay(1000); //close the lid for(pos = pos2door+15; pos<= pos1door; pos +=5) { doorServo.write(pos); delay(15); } delay(1000); //открываем крышку for(pos = pos1door; pos > <= pos2hand+2; pos +=5) { handServo.write(pos); delay(15); } //убираем руку for(pos = pos2hand+2; pos >= pos1hand; pos -=5) ( handServo.write(pos); delay(15); ) //close the lid for(pos = pos2door; pos<= pos1door; pos +=5) { doorServo.write(pos); delay(15); } } void move_3(){ //дерганый вариант: приоткрыли-подергали - закрыли-открыли-выключили-закрыли //открываем крышку for(pos = pos1door; pos >= pos2door+15; pos -=1) ( doorServo.write(pos); delay(50); ) delay(500); //pull the lid for(int i=1; i<=8; i ++) { doorServo.write(pos2door+18); delay(80); doorServo.write(pos2door+15); delay(80); static unsigned long previousMillis = 0; if(millis() - previousMillis >INTERVAL) ( previousMillis = millis(); digitalWrite(LED_PIN,!digitalRead(LED_PIN)); ) ) delay(500); //close the lid for(pos = pos2door+15; pos<= pos1door; pos +=1) { doorServo.write(pos); delay(50); } delay(1000); //открываем крышку for(pos = pos1door; pos >= pos2door; pos -=5) ( doorServo.write(pos); delay(15); ) //stick out hand for(pos = pos1hand; pos<= pos2hand+2; pos +=5) { handServo.write(pos); delay(15); } //убираем руку for(pos = pos2hand+2; pos >= pos1hand; pos -=5) ( handServo.write(pos); delay(15); ) //close the lid for(pos = pos2door; pos<= pos1door; pos +=5) { doorServo.write(pos); delay(15); } } void move_4(){ //открываем крышку delay(2000); for(pos = pos1door; pos >= pos2door+15; pos -=5) ( doorServo.write(pos); delay(50); ) delay(500); digitalWrite(LED_PIN,!digitalRead(LED_PIN)); delay(2000); digitalWrite(LED_PIN,!digitalRead(LED_PIN)); delay(500); //close the lid for(pos = pos2door+15; pos<= pos1door; pos +=5) { doorServo.write(pos); delay(50); } delay(1000); //открываем крышку не полностью for(pos = pos1door; pos >= pos2door+15; pos -=1) ( doorServo.write(pos); delay(50); ) delay(2000); //open the lid completely for(pos = pos2door+15; pos >= pos2door; pos -=1) ( doorServo.write(pos); delay(15); ) //stick out your hand for(pos = pos1hand; pos<= pos2hand-35; pos +=1) { handServo.write(pos); delay(35); } delay(1000); //высовываем руку for(pos = pos2hand-35; pos <= pos2hand+3; pos +=4) { handServo.write(pos); delay(15); } //убираем руку for(pos = pos2hand+3; pos >= pos1hand; pos -=7) ( handServo.write(pos); delay(15); ) //close the lid for(pos = pos2door; pos<= pos1door; pos +=7) { doorServo.write(pos); delay(15); } delay(500); //открываем крышку for(pos = pos1door; pos >= pos2door+20; pos -=5) ( doorServo.write(pos); delay(50); ) delay(300); digitalWrite(LED_PIN,!digitalRead(LED_PIN)); delay(500); digitalWrite(LED_PIN,!digitalRead(LED_PIN)); delay(100); //close the lid for(pos = pos2door+20; pos<= pos1door; pos +=1) { doorServo.write(pos); delay(50); } } void move_5(){ //возня for(int i=1; i <=2; i ++) { for(pos = pos1door; pos <= pos1door+45; pos +=5) { doorServo.write(pos); delay(50); } for(pos = pos1door+45; pos >= pos1door; pos -=5) ( doorServo.write(pos); delay(50); ) delay(100); ) //pull the lid for(int i=1; i<=3; i ++) { doorServo.write(pos1door-6); delay(80); doorServo.write(pos1door-3); delay(80); } delay(300); //открываем крышку digitalWrite(LED_PIN,!digitalRead(LED_PIN)); for(pos = pos1door; pos >= pos2door+25; pos -=5) ( doorServo.write(pos); delay(50); ) delay(500); //open the cover digitalWrite(LED_PIN,!digitalRead(LED_PIN)); for(pos = pos2door+25; pos >= pos2door+10; pos -=5) ( doorServo.write(pos); delay(50); ) //open the door digitalWrite(LED_PIN,!digitalRead(LED_PIN)); for(pos = pos2door+10; pos >= pos2door-5; pos -=2) ( doorServo.write(pos); delay(50); ) //stick out your hand for(pos = pos1hand; pos<= pos2hand-35; pos +=9) { handServo.write(pos); delay(35); } delay(1000); //убираем руку for(pos = pos2hand-35; pos >= pos2hand-70; pos -=1) ( handServo.write(pos); delay(15); ) delay(1000); //stick out your hand for(pos = pos2hand-70; pos<= pos2hand+3; pos +=9) { handServo.write(pos); delay(15); } delay(50); //убираем руку for(pos = pos2hand+3; pos >= pos1hand; pos -=7) ( handServo.write(pos); delay(15); ) //close the cover digitalWrite(LED_PIN,!digitalRead(LED_PIN)); for(pos = pos2door-5; pos<= pos1door+3; pos +=5) { doorServo.write(pos); delay(50); } }

The sketch suggested by the author from the link at the beginning of the review did not work for me. And I was not yet the pro that I am now)))))))
In general, I began to understand. As a result, based on someone else’s, I made my own sketch. Added anti-bounce protection. It would have been easier, of course, to install a resistor with a capacitor, but I really wanted to program it.

In principle, the scheme is clear from the sketch. But I’ll bring her anyway. Sorry for the quality - as best I could. I took a slightly different converter board - I didn’t find it needed in the front view.

Youtube has greatly degraded the quality. If you need to look at the original, download it. 21 MB.
Here the sketch has been modified to allow you to see all six programs in turn so that you have an idea of ​​them all. In life, as I wrote, they have a pseudo-random order.

$6.3 (currently 1.43)

I bought an Arduino Pro Mini complete with a USB-UART adapter on a CP2102 chip 1.5 years ago (prices for them have dropped significantly since then) and they have been lying on my shelf all this time. Everyone couldn't get around to doing anything on this controller. An important role in this was played by the fact that flashing a sketch in Arduino Pro Mini, although not difficult, is a little more difficult than in Arduino UNO, Mega or Nano.

And so I decided to use this controller in one of my projects, it still lies idle.

I happened to have a 16MHz 5-volt model on an ATmega 328 chip. As it turned out when analyzing data from the Internet, there are controller boards that do not have the DTR signal routed. In my case, everything is wired correctly. The kit included a USB-UART converter.

The platform contains 14 digital inputs and outputs (6 of which can be used as PWM outputs), 6 analog inputs, a resonator, a reset button and pin mounting holes. A block of six pins can be connected to a USB-UART converter board.

Arduino Pro Mini is very similar in its technical characteristics and parameters to Arduino Nano. They are the same size in width, but the length of the Arduino Pro Mini is about 1 cm shorter.

10 mm is a lot. But if you solder the pins for connecting USB-UART into the board, all the advantages of this board over the Nano disappear. At the moment, Arduino Pro Mini costs $0.25 less than Arduino Nano. It's immaterial. There are no more advantages and disadvantages, only disadvantages.

And the main disadvantage is the more complex loading of sketches.

There are several ways to flash a sketch.

One way is to use an Arduino UNO as a USB-UART. There are a lot of instructions on the Internet on how to do this, so I won’t dwell on it.

The second way is to use the USB-UART adapter itself. I have it, and the “correct” one, so I decided to use it. How does the adapter work? Arduino communicates with the converter chip via a regular UART, and connects to the computer via USB. The computer recognizes the connected adapter as a COM port.

Uploading the sketch to the Arduino Pro Mini, as it turned out later, is not at all difficult. You just need to connect the wires from the set of 5 pins on the adapter and Arduino:

(Converter)<->(Arduino)

DTR<->GRN
TXD<->RXI
RXD<->TXO
GND<->GND
5V<->VCC

On my Arduino Pro Mini the DRT signal is labeled GRN. It was not easy to guess what was what, especially since on one of the sites a “kind” advisor wrote that GRN needs to be connected to GND. Well, the Internet is a big garbage dump, and this is not the first time I’ve been convinced that the people most willing to give advice on forums are not those who really understand the subject under discussion. So, GRN is DTR.

For those who don't know what DTR is:
Data Terminal Ready (DTR) - control signal in serial data protocol, transmitted from terminal equipment (DTE) to the receiving equipmentto indicate that the terminal is ready for communication.

In Arduino, the DTR signal initiates the Reset signal the moment the sketch starts transferring.

Possible instead of DTR connection<->GRN connect the DTR adapter through a 0.1uF capacitor to Reset Arduino Pro Mini. It works that way too, tested. It is through the capacitor. Despite the fact that it is written on forums and many sites that you need to connect DTR and RESET directly, with a direct connection the sketch is not transferred. At least nothing worked for me with a direct connection.

Theoretically, as they write on the Internet, you can record a sketch without DTR by pressing reset on the controller board exactly at the moment the recording begins. I tried several times to catch this moment, but I couldn’t. I didn’t train my skills in trying to reset at the right time; it’s easier to trust the CP2102 converter chip to supply the Reset signal.

But not all CP2102 are created equal. There are a lot of cheap fakes sold on eBay and AliExpress that people struggle with and often have to modify so that they can record a sketch in the Arduino Pro Mini. In these adapters, the DTR signal from pin 28 of the CP2102 chip is not routed. Some have the Rx and Tx markings mixed up. That’s why there are so many instructions on forums online that contradict each other and sometimes simply mislead readers. I spent about two hours reading these nonsense (I didn’t want to reinvent the wheel, I thought I’d save time) and trying to write a sketch into the controller using these instructions. As a result, all the instructions turned out to be non-working for my CP2102 adapter. It turned out to be the “correct” one, in which the correct markings were applied and all the signals were correctly routed.

It was enough just to connect all the wires and everything worked.

Therefore, if you are faced with the need to record a sketch in Arduino Pro Mini via USB-UART, first check whether the DTR signal is routed on the Arduino Pro Mini board. I read that there are boards on which it is not routed. In this case, you can use the option of connecting the DTR signal from the USB-UART adapter board to the RESET pin of the Arduino Pro Mini via a 0.1-0.15 µF capacitor.

Secondly, check whether the DTR signal is connected to any pin on the USB-UART adapter board. The pin can be, and even be signed as DTR, but not connected to pin 28 of the CP2102 chip. If pin 28 of this microcircuit is not connected anywhere, you need to ensure its connection to the DTR pin. If pin 28 is connected somewhere in the circuit, this track needs to be cut and connected directly to the DTR pin.

The correctness of Rx and Tx markings on a fake CP2102 board can be determined experimentally; there are only 2 options.

I also read instructions on the Internet that you need to record a sketch using the USB-UART adapter CP2102 in the “Upload via programmer” mode, supposedly this is the only way everything works. I don’t know whether the author of this opus is deliberately misleading readers, or whether he had something other than a CP2102 USB-UART adapter, but this advice is WRONG!

Through the USB-UART adapter CP2102, the computer sees the Arduino Pro Mini as if it were connected to a COM port, that is, just like other Arduinos that have a USB-UART adapter on board.

Therefore, sketches are uploaded to Arduino Pro Mini in the same way as to other Arduino models. You only need to select the Pro Mini model in the Arduino programming environment, then in the additional item that appears, select one of 4 possible types of processor (ATmega168 or 328, 3.3 or 5V) and the virtual COM port that appeared after installing the USB-UART adapter drivers. Then you can use the download button or Ctrl-U. If everything is connected correctly, the type and model of the adapter does not matter, the sketches are uploaded via UART. We simply select the COM port that the adapter is determined by.

After 2 hours of reading forums and sites with “guides” and “tips”, which were 99% incorrect, at least they were not suitable for my specific Arduino Pro Mini models and USB-UART adapter CP2102, I managed to connect and upload everything correctly into the controller a slightly modified sketch of LED blinking. I made him blink SOS in Morse code.

Here's a sketch, in case anyone is interested:

// the setup function runs once when you press reset or power the board
void setup() (
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
}

// the loop function runs over and over again forever
void loop() (
delay(100); // wait
delay(300); // wait
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(100); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300); // wait
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(100); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300);
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(300); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300); // wait
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(300); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300); // wait
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(300); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300); // wait
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(100); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300); // wait
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(100); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300); // wait
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(100); // wait
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(300); // wait
delay(1500); // wait 1.5 sec.
}

Conclusions:

If I had not tried to save time by “reinventing the wheel” and had not spent time reading useless (even rather harmful) tips and guides on forums and websites, connecting and flashing the Arduino Pro Mini would have taken not 2 hours, but a maximum of 5-10 minutes .

I bought my set of Arduino Pro Mini and USB-UART adapter CP2102, which by today's standards was quite expensive. The truth is that I am consoled by the fact that the adapter is correct and all the signals are connected to it.

Arduino Nano is identical in parameters and capabilities to Arduino Pro Mini, costs just a little more (maximum 25-50 cents), loses 1 cm in size (and with soldered pins the Arduino Pro Mini does not lose at all), but is much more convenient in use due to the built-in USB-UART and the common MicroUSB connector.

Arduino Pro Mini is not the most popular board, type “Arduino Nano” in a search on eBay and sort by price in ascending order and you will see how the cunning Chinese are very cheaply selling a lot of Arduino Pro Minis in this section, passing off as Nano? in the hope that the buyer will not figure it out and, taking advantage of the low price, will buy these controllers. They have all their hope only in customers who are suckers.

Would I recommend buying an Arduino Pro Mini? For a beginner - no. Yes - to a person who knows exactly what it is, what disadvantages it has and whether they are worth the meager savings.

I repeat once again that flashing the Arduino Pro Mini is not difficult, but is this fuss with connecting the wiring or the Arduino UNO worth the price difference of $0.2-$0.25. Especially if you have to connect the controller to the computer for debugging many times, but what if it’s in a case? If you think that connecting and disconnecting 5 wires ten to fifteen times is more profitable than paying 20 cents, this controller is for you.

That's all. I shared my experience and expressed my opinion, it’s up to you to decide.

P.S. A little time passed and I somewhat changed my opinion about the Arduino Pro Mini. Even a savings of 25-50 cents is a lot, especially if a small batch of products using this controller is assembled. It is clear that for a small batch it is better to integrate the controller directly onto the board, rather than using a ready-made Arduino (this is still more of a debugging board). But there are different options, sometimes there are already ready-made boards and you can upgrade them and expand their functionality by integrating Arduino. It will be cheaper than building new boards.

And the presence of a USB-UART adapter on board the product handed over to the user is completely unnecessary and even harmful. So Arduino Pro Mini has the right to life.