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General Electronics / Re: Switching voltage regulato...
Last post by MarkT - Today at 04:53 pm
Capacitors do in the time domain what inductors do in the frequency domain. Does that make more sense?
Project Guidance / Possible to add start/stop fun...
Last post by landryk19 - Today at 04:52 pm
I have written a sketch that reads a water pressure transducer. It is used to read pressure during experiments... these experiments can last up to 2 hours. Is there a way to have Arduino constantly on and reading the transducer but have a "trigger" function to have it read and write out to a file only when I need it to? I don't want to be dealing with unnecessary data but I still want to see it on the serial plotter.


Here's the current sketch:

int S1Pin = A1; // Sensor 1 is connected to pin A1

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:

// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 1:
  int sensorValue = analogRead(S1Pin);
  // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
  float voltage = sensorValue * (5.0 / 1023.0);
  // print out the value you read:

delay(10); // Pauses the program for the amount of time (in milliseconds) specified as parameter. (There are 1000 milliseconds in a second.)

General Electronics / Re: Optocoupler Current Requir...
Last post by MarkT - Today at 04:51 pm
Use 220 ohms, you have to allow for the voltage rail being a bit low, the LED forward voltage being a bit high
and the series resistance of the output drivers (which will be 50 ohms or more anyway)
Audio / Re: How can I play audio in ex...
Last post by 7A15 - Today at 04:50 pm
Thanks for your answers. The TMRpcm library looks good, I will try it. Also it could be useful to play two audios at the same time (One in the background and one over it). As the documentation says:

Asynchronous Playback: Allows code in main loop to run while audio playback occurs.

Thanks again.
Project Guidance / Midi input to control bank of ...
Last post by jcmusix - Today at 04:47 pm
Hello Community!

 I would like to request input from the community about my approach. The overall scheme of what I am attempting to do is to operate a player piano with a bank of 85 solenoids ( plus some others for pedal control, etc.) My project is well underway. I have the solenoids working as valves in a row tee fitting connected to the vacuum hoses. To control the solenoids I have an arduino uno running 6 daisy chained tlc5940 chips ( including a lot of diodes, transistors, and some resistors.) This works well! I can make the piano play by controlling the solenoids off and on with a basic pin on/off sketch so everything is in place and tested. The piano can play rapid notes and chords by tediously keying in arrays of output pin numbers and delay times in the sketch.

 Now I would like to take it to the final step of being able to feed midi file signals to control the solenoids and actually play midi music but here is where I am stuck. What would be the best approach for me to use for this final step?

Do I need to purchase a midi controller add on board?

Should my Arduino Uno be able to run both a midi input sketch and give instructions to the multiplexing sketch at the same time?

Should I do something like use a Raspberry Pi instead of or in addition to the Uno?

Thanks in advance for any thoughts or suggestions.

John Chaplain
North Port, FL

General Electronics / Re: about h-bridge diode
Last post by MarkT - Today at 04:46 pm
You don't need diodes when using a MOSFET bridge because power MOSFETs all have body-diodes.

BTW the max current and voltage are the max current of the load, the max supply voltage x a
safety factor.
Hardware / Re: Hormiguero monitoreado por...
Last post by ArduMyth - Today at 04:46 pm
Mi error porque ví que te puse 200, son de 220 efectivamente, usa esas resistencias ;)
Lo del Vc que es la alimentación no se trata que tengas dos, sino que los 5V los compartes.
Si el amperaje de tu Arduino para todo lo que vas a usar se queda corto entonces tendrás que usar una fuente de alimentación externa, por ejemplo; una batería.
Common encoders either report an incremental change in position, or absolute shaft orientation. Where do you think "overflow" might take place?
Software / Re: Arduino micro Sd Lectura
Last post by ArduMyth - Today at 04:43 pm
pues no entre a hacer lo que se me da la gana
solo entre a hacer una pregunta de la cual llevo 1 semana sin parar intentandolo hacer y pues no ha resultado nada, he buscado en varios lugares informacion pero nada y asi que desidi como ultima ruta hacer esto
Te voy a ser muy claro. Clic en icono navegador Chrome. Se abre google. Pongo en el campo: "arduino lectura SD" y me sale esto cómo primer resultado:

¿Llevas 1 semana para ejemplos que trae la propia librería y que se encuentran con búsquedas normales?
A mí, disculpa pero no me cuadra. No obstante ahí tienes más información.

Fíjate qué has dicho que el Moderador SIEMPRE, espera que subrayo,SIEMPRE es tan negativo.
Si llevabas 2 post y acabas de entrar al foro, ¿cómo puedes hacer dicha afirmación?

¿multicuenta que quizás ya fue apercibido?
Yeah (using an RPi not a Linux laptop to be clear.. although not sure if that changes any advice.)...   I tried to use the cable.. for whatever reason, it didnt dawn on me that I would need to change the PORT name.. so I went back to the USB cable and CAPACITOR..

Same results... ports open fine.. but I cant really get any READ data from it...  in some random scenarios, which I havent been able to pinpoint/nail down as repeatable,....  I -will- actually get a READ response..

But that has been 'triggered' by actions like:

* rebooting the RPi with Arduino connected  and having the cap in and/or out (RESET/GND pins)
* doing the above... but already having the webpage at the 'SUBMIT' state
* leaving RPi powered.. but unplugging the Arduino/USB  (with and without the capacitor connected)..

again.. SOMETIMES... things start working...  but I cant for the like of me find out what combination makes it 'repeatable'..

*** of course.. my director/manager isnt here today.. so of all days, I have the day to 'play'.. but I have NO HARDWARE (anything) with me today!!   (bummer)

I dont want to open the port at command line (per se`)...

I was looking/reading that you can 'disable' the DTR (reset) command on the RPi.. so the USB connected Arduino will NO LONGER reset when the port open command is being sent...

With the second AJAX approach posted above.. I am not clear why this is so difficult now!!  :P

With the cap in place.. I do NOT see the Arduino resetting when the port opens.

Talking out loud here:

Is this really a PORT OPENING thing?  If the SENDING of data works.... the PORT is already opened and working correctly......right?  Especially in the SECOND approach posted above>?  Since the WRITE and then READ is done int he same snippet of code.. under the ONLY port opening line in the app?  SO if the WRITE is working after the port opening...  why isnt the READ portion working?  Its all 'working' under the same PORT OPENING action......right?

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