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1  International / Proyectos / Re: Regulador de carga Fotovoltaico on: March 14, 2014, 06:12:39 pm
El que este relé "latching" se active con pulsos, y esos pulsos los controles con otros relés, es complicado. Y si pruebas con unos transistores (grandes)?  Unos TIP31 por ejemplo.
2  International / Proyectos / Re: Enviar SMS cuando se encienda un LED on: March 13, 2014, 05:16:38 am
Hay muchos ejemplos en la web de código para enviar sms. Todo depende de que modulo compres. Si es un shield es mas facil. Yo tengo una linksprite sim900 y es muy simple.
3  International / Proyectos / Re: Ayuda con proyecto para tablero del auto on: March 13, 2014, 05:11:13 am
tenes que tener en cuenta que el auto tiene 12v y loa terminalea de arduino no soportan más de 5v. Hay varios circuitos para hacer esta conversiones.
Para el sensor de aceite, o engancharte a cualquier cosa que prenda una luz en el auto, vas a usar un puerto digital. Pero antes tenés que ver que polo es el que maneja el sensor,  normalmente interrumpen la masa. Con esto sabrás que componente y circuito usar.
Las entradas analógicas miden voltaje y no corriente. Tienes que ver qué es lo que varía en tu indicador y von esto sabremos que circuito usar.
Saludos y que te diviertas
4  International / Proyectos / Re: Regulador de carga Fotovoltaico on: March 12, 2014, 07:17:32 pm
El datasheet dice que el pulso debe ser de 100ms, y el que estás poniendo es de 200ms. No sé si eso puede ser la causa.
No entiendo por qué usas dos If...con la estructura como está, si el voltaje es 13.4 no entra a ninguno.
Tienes un esquema del circuito que estás usando?
Veo que haces varios castings con los float, reconozco que no soy un experto en ese tema, pero si se que eso me ha dado muchos dolores de cabeza. Yo manejaría el voltaje siempre como un entero, y solo lo convertiría a float para mostrarlo.
Cual es el modelo exacto del relé que estás usando? Si le envías dos pulsos seguidos al mismo contacto, cambia o no cambia?
5  International / Proyectos / Re: Regulador de carga Fotovoltaico on: March 12, 2014, 05:43:21 am
Para enviar un pulso tienes que poner el pin en un estado, luego tener un delay y volver a cambiar de estado el pin.
6  Using Arduino / Project Guidance / Re: Remote fire a Canon 5d Mark II with Arduino Uno REV 3 on: February 25, 2014, 07:08:21 pm
You can either hack your Canon remote, or use an IR Led wired to the arduino to transmit directly, but you´ll need to know the code that it should transmit, and select the proper IR led.
Heres is some info about that:

As for the turntable, if you are controlling the stepper motor that makes it turn, you will need to count the steps needed to get a complete turn, an then fire the camera. But the thing is how to syncronize it. I used to work with electronic roulettes, and this devices used a small piece of reflective material and an optocoupler to detect when the right spot was in front of the sensor.
Does this sound good for you?
7  Using Arduino / Project Guidance / Re: USB drive selector on: December 02, 2013, 09:29:57 am
Thanks for your help guys. I'll do some tests as soon as I get the right connectors.
8  Using Arduino / Project Guidance / USB drive selector on: November 30, 2013, 06:58:53 am
I use multiple USB hard drives to do backups. They are rotates, so yo don't use the same drive two times in a row.
This operation is done manually, and I wnat to automate it. And Arduino came instantly to my mind.

I don´t know anything about USB connections. So looking at a pinout I discovered that there are just four cables, a pair for data, and a pair for power. My idea is using 4 Logic Level Mosfets to open the connection to each USB drive, having all gates wired together to an Arduino Pin.
The Arduino would run a timer, putting just one pin HIGH to select a USB drive, the others LOW.

The arduino programming part is something that I can do. The USB selection is my question. Will the Mosfet approach work?
Are Multiple Switch ICs or Multiplexer adecuate for this requirement?

9  Products / Arduino GSM Shield / Re: Turning on/off Linksprite SIM900 shield on: October 28, 2013, 03:42:35 pm
Thanks gerschwin. I see that the sketch I was using is like yours and is ok.
I tested it in another shield and it works. It was a hardware problem.
10  Products / Arduino GSM Shield / SOLVED: Turning on/off Linksprite SIM900 shield on: October 27, 2013, 09:14:25 am
I have a Linksprite SIM900 shield, that I got to work except for one thing: I´m not able to turn it on and off usig the D9 pin.
This is the shield:
The sim900 datasheet states that a pulse > 1.1sec would get the shield on or off. Since the D9 pin is wired to a transistor, I´m seting the pin HIGH for 2 seconds and then back to low. But nothing happens..not on and not off.
As an alternative to turn it off I´ve used the AT+CPOWD=1 command, which works fine.
The powerkey works with no problem. I have to hold it for almost 3 seconds to turn the shield on or off.
I found this page, but the solution doesn´t work either:

Anyone has the same experience?
11  Products / Arduino GSM Shield / Re: link sprite sim900 GSM/GPRS on: October 27, 2013, 08:54:08 am
Have you seen this tutorial:
Use always an external power soure. I´ve used a 5V 1Amp wall wart and worked fine.
12  Using Arduino / Project Guidance / Reading wiegand and publish data to the web on: September 05, 2013, 09:06:43 pm
Dear Arduinoers,
I´m facing a new project that involves logging data from an RFID reader and publishing the data to the web via a Web Service, using a mobile data connection.
I assume that the data link won´t always be on line, so I will use a SD card as a buffer.
The RFID reader gives as output a Wiegand signal, that I can process. Timestamping this input from an RTC and storing this in an SD card is something doable.

Since I want to publish the stored info to the web, comunicating with a web service via the mobile link, I can't build a clear picture of how to read the data and not blocking the SD card from incoming new data from the RFID reader.
I thought of using 2 arduinos, one that reads and stores the data in the SD card, and another one that tries to transmit the data. A pin would be used to take turns in using the SD card, giving preference to the writing process, so that if the first one is storing incoming data, the other one is unable to acces the SD card, and if the second one is reading and the first needs to store something, I can break it using an interrupt.

But this sounds like a complicated solution to a simple problem. The thing is that I don't have the RFID reader available, so as to test how frequently it can send data.
Any other Ideas will be welcome.

13  International / Español / Re: EEPROM 24lc256 on: March 22, 2013, 02:45:43 pm
Yo usé siempre estas memorias escribiendo y leyendo de a un solo Byte, usando solamente I2C_eeprom_write_byte, I2C_eeprom_read_byte.

El tema principal es que tienes que descomponer (y luego rearmar) tu valor long en 4 bytes, y esos enviárlos (y luego recuperarlos) de la EEPROM.

Acá hay algunas soluciones:

Con esto resuelto debería ser simple el almacenaje y la lectura, que tendrías que hecerlo cuatro veces (una por cada Byte).

Espero esto te ayude.
14  Using Arduino / General Electronics / Re: rs485 - is shared ground required? on: March 19, 2013, 11:05:40 am
Reading this article it states that:
Without a common ground, the circuit may work, but the energy from the imbalance has to go somewhere and may dissipate as electromagnetic radiation.

I've made 485 circuits without a common ground, and they worked anyway. I've grounded just one end and it worked transmitting shiftout data at 60meters without problems. Maybe I was just lucky smiley-wink

15  International / Hardware / Re: Detector de golpes con transductor on: March 12, 2013, 03:38:44 pm
Todo depende del tipo de golpe que quieras medir.
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