Add a 10K resistor everything works as perfectly. When PB is not pressed and place my finger close to the wire connected to pin 40 the led begins to flicker indicating I need a pull-down resistor. The PB when pressed should turn a LED on. I have a 2560 with a PB between 5v and a pin 40. All of which is to say you should double check the actual resistor values using the colour bands and something like the chart from the link above. Mega 2650 and pull-down resistor questions. It would be interesting to see if you had a multimeter that would verify that number. The analogWrite function provides a simple interface to the hardware PWM, but doesnt provide any control over frequency. = 150 * (5.0/1023) * ((1012 + 100) / 100) So your display would show "V= 8.15" and 9v batteries are typically 6.5v to 8.4v. The Arduinos programming language makes PWM easy to use simply call analogWrite (pin, dut圜ycle), where dut圜ycle is a value from 0 to 255, and pin is one of the PWM pins (3, 5, 6, 9, 10, or 11). Microcontroller: ATmega2560 Operating Voltage: 5V Input Voltage (recommended): 7-12V Input Voltage (limit) : 6-20V Digital I/O Pins: 54 (of which 15 provide. If the arduino was seeing a value of 150 when V_in was 9 volts the ((R1+R2)/R2) ratio would need to be: 9 / (150 * (5/1023)) = 12.276 Now, looking at the image you posted it's a bit hard to make out the resistors, but from what I can see and translating the resistor colour codes ( ) you have 2 x 506k for R1 and 1 x 100k for R2 - ((R1+R2)/R2): ((506k*2 + 100k) / 100k) = 11.12 Which is pretty close to the 12.276 ratio above if V_in were 9v, so using those values: voltage = value * (5.0/1023) * ((R1 + R2)/R2) 8.152. DC supply can be given via power jack or by using USB cable port. 5 volt supply can also be generated and regulated on board. 3 voltage supply can be generated with the help of on board regulator and the maximum current is 50 mA that can pass through it. Otherwise some pins will be low, and others high creating effectively a dead short. Secondly, you have to be careful to change all the pins at exactly the same time. The sum of all IOH, for ports F0-F7, K0-K7 should not exceed 100mA. The noise margin is greater on the Arduino and it has a. The sum of all IOH, for ports E0-E7, G5 should not exceed 100mA. = 150 * (5.0/1023) * ((200+10)/10) So the arduino is outputting a value of 150, which corresponds to it seeing a voltage of 0.733. Input Voltage (Limit), 6-20V Input Voltage (Recommended), 7-12V Microcontroller, ATmega2560 Operating Voltage, 5V Ports, 54 digital pins, 16 analog inputs. Arduino Mega 2560 can have power supply of two voltages i.e. The most noticable difference is that the invalid region of voltages is only between 1.5 V and 3.0 V. First off, for the number to show up like that the values of the voltage = value * (5.0/1023) * ((R1 + R2)/R2) equation come out to: 15.39589. This was a fun little puzzle to work out.
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