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Why do you think that the motor axis position is the best information source? Isn't there a gear box, after which the rpm is much lower and the position is more precise?

Why do you think that the resolution must be so high? Taking into account mechanical tolerance of the actors, a 1% accuracy looks good enough to me. What's the full stroke of the actor?

Is there a way to extract the lower half of the 64-bit address of the source XBee of a receive packet, and save it to an uint8_t array? (e.g. If I received a packet from 0013A200 4157310A, I will save {41 57 31 0A} to an uint8_t array.)

I am using XBee.h library by Andrew Rapp, and XBee Zigbee PRO modules.

Thanks in advance!
Sensors / Re: Turning light sensor into ...
Last post by Johan_Ha - Today at 02:26 am
The hobbyist way to do a colour sensor is to use an RGB led and a light dependent resistor. I've done that and it was fun. I think I reached a "RGB measurement, band by band, at a rough accuracy and repetability".
Perhaps you could describe more in detail how you intend to use your sensor. Are you doing an error at the measuring moment, like expecting the sensor to "see" the colour of an object from a short distance?
Thank you. I didn't know there was a source for hourly builds so that's good to know about, though as you note it's probably a bad idea to roll it out to a 100-user environment. I'm only slightly less nervous about updating the AVR core by hand in place... I wonder how that might interact with the board manager. I'll probably be juuuuust dumb enough to try it out in lab tomorrow. But all of these not-great options are being measured next to Plan A, where students have a slightly daunting flow chart to work through just to get Blink to upload.

(I realize I represent a corner case where I have maybe 200 Gravitech and Arduino Nanos of various vintages kicking around, but breaking backwards compatibility like this is close to my perfect nightmare scenario. It's going to take years for my concentration of Optiboot Nanos to get to 100%. That the Nanos being sold by Arduino for the last 8 weeks can't be programmed by the most up-to-date public IDE (without mucking around with the AVR core) is honestly a decision I find totally baffling.)
Software / Re: lectura de dht22 en things...
Last post by gerardoramirez11 - Today at 02:23 am
Hola, si pudiste conectarte?

Hay un ejemplo exitoso que tu ayudaste a resolver. El hilo es: lectura de dht11 en thingspeak usando arduino uno y SIM900 el nombre del muchacho es Neythan y fue el 2 de enero.

Estoy atento,
it seems like theres no output to pin 6 and i cant get the arduino program to recognize it. Is this fixable?
If it's an Uno with the chip in a socket then you can replace it with a bootloaded ATmega328P or AVR from the same family.

You can buy them, you can buy bare new AVR's and with a working Arduino, a breadboard and a few parts, bootload you own. Compare the price of blank 328P's to bottloaded 328P's on eBay.
Hardware / Re: Proyecto Cultivo
Last post by zanack - Today at 02:15 am
gracias, ya vienen en camino los dht22 y los sensores de humedad, la bomba ya la conseguí es de un auto, en cuanto llegue lo otro me pondré a armarlo, ahora leí por ahí que los medidores de humedad que van en tierra no duran mucho, sabes que tan cierto es esto? si es asi deberé cambiarlos cada x tiempo o ver alguna solución más duradera
Hardware / Re: Relés 12v no funcionan
Last post by tauro0221 - Today at 02:15 am
Pregunta que tipo de relay estas usando? Puedes decirnos el modelo del relay que estas usando para saber como se conecta. Aparentemente segun tu dibujo se ve que la coneccion esta correcta pero no sabemos las espeicficaciones del relay para poder hacer un diagnoctico de como resolver tu problema.
Project Guidance / Re: 12 Volt car battery emerge...
Last post by INTP - Today at 02:14 am
1750mAh (aka 1.75Ah) will run a string of 300 3528 LEDs (5 meters @ 60leds/meter) for 1 hour.

Saying something like "But I would think that a small 12 volt led array could go for several hours on a battery charge?" is absolutely meaningless. You don't mention how big your battery is.  :smiley-roll:
A 10Ah battery will give a little over 5.5 hours. A 75Ah battery gives like 43 hours. Optimistically, and depending on how deep you want to discharge that battery. And that's with the LED strip that I mentioned. You haven't mentioned what LEDs you're talking about.
Programming Questions / 10-bit pwm stops at 255
Last post by kebo - Today at 02:12 am
Hey all,

I've configured my 2560 Mega board for a 10-bit PWM output on pins D2 & D3 running at 7.82kHz by setting these registers...

Code: [Select]
//set TCCR3A
//TCCR3A = 0x01; //8-bit
//TCCR3A = 0x02; //9-bit
TCCR3A = 0x03; //10-bit

//set TCCR3B
TCCR3B &= 0x01; //set the prescale = 1 to get the highest pwm frequency

I have also created a class to which I can pass a float from 0.0 - 5.0 that sets the mean output of the pwm in volts. This is that class...

Code: [Select]
void DataPoint::begin(float _min, float _max, int _filterWeight,int _maxPWM)
//the _min & _max are the limits that can be passed to the Set method  (i.e 0.0, 5.0)
//_filterWeight is the capacity of the moving average (not relevant for my problem)
//_maxPWM is 256, 512 or 1024 depending on the bit level of the PWM

maxPWM = _maxPWM-1;
FilterWeight = _filterWeight;
Min = _min;
Max = _max;


void DataPoint::Set(float newSetPoint)
//for now, Min is always 0 to make scaling simpler
//get the percent of the analog out
float percentAnalog = (newSetPoint / Max);

//mul the percent by the max PWM output to get the PWMSetPoint
pwmSetPoint = (int)(percentAnalog * maxPWM);

//make sure the pwmSetPoint is in range
if (pwmSetPoint > maxPWM)
pwmSetPoint = maxPWM;

//write the output
analogWrite(controlOutPin, pwmSetPoint);


This all seems to work fine UNLESS the pwmSetPoint = 255. In that case the pwm signal coming out of D2 or D3 rails to 5V. It's as if I have set a 10-bit PWM to 1023.

Can any one see what the problem is and how to fix it?
Thanks for your time

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