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Sensors / Re: use BMP 280 without a dedi...
Last post by Koepel - Today at 03:18 pm
General Electronics / Re: Pro mini fried RAW input
Last post by bpjobin - Today at 03:18 pm
Please explain what you did.
I meant soldering wires directly to pins on the board and on each components the same way it was wired on the breadboard prototype.
Hardware / Re: Problema con funcionamient...
Last post by surbyte - Today at 03:18 pm
MAC mi direccion es 002194273DA
Eso que lees es 0x00 0x21 0x94 0x27 0x3D 0xAX falta un digito en algun lado.
Sensors / Re: BMP280 GY - does it always...
Last post by falexandru - Today at 03:17 pm
@Koepel - Thank you!
You really saved me. I was planning to go feed the A Nano on external power (that is the next phase of my project). So far I run it on PC USB, on a 2 m cable (now I found that was a good thing).
today I am  going to buy level shifters (few types, as the Sparkfun one is indencently expensive).

For a buck (see Tom Waits :-)))

or this one:

This one is around 3 USD:

They all claimed to be biderctional and looks like woirking on I2C. But I am not very convinced.


I was thinking to 3.3 boards as well. But I have to build external 3.3 V sources, which are not so usual. On the other hand, I can - perhaps - go down to 3.3. V from one  3.7 LiIon 18650 unit, which would be nice.

Another point is that I love the Arduino nano! Is a little piece of engineering genius: matches mini breadbord, it is large enough to read the pins (by special glasses but anyway).


When we know a little bit on how serial data communication takes place between PC/Serial Monitor and UNO, the program writing job becomes entertaining!

1. Assume that we have placed the cursor in the InputBox of the Serial Monitor. Type the character A or any other character from the keyboard and then click on the Send button.  

2,  The character has ultimately arrived at the Receiver Section of the UART Port of the MCU of the Arduino UNO.

3.  The Receiver Section immediately interrupts the MCU; the MCU automatically goes to the
subroutine (the interrupt subroutine, ISR) named serialEvent(); it reads the the character (the 8-bit ASCII code for A = 0x41) from the receiver and saves into a FIFO type buffer. The buffer is not visible to the programmer; but, Arduino has provided functions to access it.  

5.  In the ISR, we can examine the buffer to be sure that the received data is there. After that, we can bring out (read) the data byte from the buffer and send it back to the PC/Serial Monitor. The character A will appear on the OutputBox of the Serial Monitor.

6. Im presenting below a tested (demonstrative) program with which you can play around. Considering this one as a building block and taking further help from the Forum/Net (Serial Input Basics) we can develop much more elegant and complex programs on serial communication.
Code: [Select]
//chracter echo program
//in the Serail Monitor, keep NL & CR enabled.

void setup()


void loop()
  //wait here to be interrupted by the Recever Section of UART Port
  //whenevr a character arrives


void serialEvent()
  //check that charctaer is saved in the buffer using Serial.avaiable() function
    //bring out character from FIFO type buffer into user variable using function
    byte x =;  //character is read from buffer; the FIFO buffer is empty
   //send the charctaer back to PC/Serial Monitor


}   //the control goes back to loop(0 function

BTW: Can you tell how many characters have actually come from PC to the UNO? If there are 3, then we see only one -- A; where are the other two?  

Software / Re: Consulta - Controlar varia...
Last post by surbyte - Today at 03:15 pm
Tienes algunos problemas con las llaves que te muetro aca

Code: [Select]

  //t1 es el sensor de temperatura 1
  If (t1 < 105) {
    digitalWrite(RELAY1, LOW)
  If (t1 > 110) {
    digitalWrite(RELAY1, HIGH)

  //PARTE HUMEDAD. mide, si es menor a 90, prende fan 20 seg y 2seg ev; espera 20seg entre cada medición a que ambiente se regule, y vuelve a medir y repetir
  If (h1 < 90) {
    If ((ahora - anteriorET1)>=tiempoH1) {
      digitalWrite(RELAY2, HIGH) //APAGA FAN SI PASARON 20 SEG
      anteriorET1 = millis();
        If ((ahora - anteriorET1)>=tiempoEV1) {
             digitalWrite(RELAY3, HIGH) // APAGA LA EV1 A LOS SEGUNDOS QUE DIGA LA VARIABLE "tiempoEV1"
        } else {  // <== Faltaban  llave que cierra anterior y empieza else
             digitalWrite(RELAY3, LOW) // PRENDE LA EV1   
             digitalWrite(RELAY2, LOW) // PRENDE EL FAN   
General Electronics / Re: Pro mini fried RAW input
Last post by jremington - Today at 03:15 pm
When I tried to make it more permanent
Please explain what you did.

I'll take any advice you guys have!
Avoid idiot Fritzing diagrams, as they are usually confusing and misleading. What is the black thing labeled "VREG" and what are the associated pins?
Programming Questions / Re: Dmx simple question
Last post by Jerzkie - Today at 03:13 pm
See if it is more obvious in hex.
0x31 0x32 0x33 'c' ... 0x34 0x35 'w'

Note that the ASCII representation of a decimal digit is not the value of the digit, it is the value of the digit plus 48/0x30/'0'
value = 10*value + c - '0';

i dont know what is the purpose of that sir. all i know as from the given data 123c45w

(c - '0') 49 50 51 99 52 53 199  to 48

what is the purpose of that equation i'm confused
Deutsch / Re: 1 Röhre Nixie Uhr
Last post by phillert - Today at 03:13 pm
ich glaube du verstehst mich gerade falsch

was ich meine ist wen die zahl Null 0000 wie mache ich eine 0110 daraus
A common way to achieve slow turn on of a mains device is to use a negative temperature constant resistor in series with the load.

RS, Farnell, Mauser etc keep loads in various current ratings.

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