User manual

www.sainsmart.com

running at Vcc = 5 volts. In that case, a value of 255 will also be 5 volts. We can then easily

convert the desired voltage to the digital value needed using simple division. We first divide the

voltage we want by the 5 volts maximum. That gives us the percentage of our PWM signal. We

then multiply this percentage by 255 to give us our pin value. Here is the formula:

Pin Value (0-255) = 255 * (AnalogWrite / 5);

Arduino use analogWrite()

analogWrite() ：Writes an analog value (PWM wave) to a pin. Can be used to light a LED at

varying brightnesses or drive a motor at various speeds. After a call to analogWrite(), the pin will

generate a steady square wave of the specified duty cycle until the next call to analogWrite() (or a

call to digitalRead() or digitalWrite() on the same pin). The frequency of the PWM signal is

approximately 490 Hz.

On most Arduino boards (those with the ATmega168 or ATmega328), this function works on pins

3, 5, 6, 9, 10, and 11. On the Arduino Mega, it works on pins 2 through 13. Older Arduino boards

with an ATmega8 only support analogWrite() on pins 9, 10, and 11.The Arduino Due supports

analogWrite() on pins 2 through 13, plus pins DAC0 and DAC1. Unlike the PWM pins, DAC0 and

DAC1 are Digital to Analog converters, and act as true analog outputs.You do not need to call

pinMode() to set the pin as an output before calling analogWrite().The analogWrite function has

nothing to do with the analog pins or the analogRead function.

Syntax

analogWrite(pin, value)

Parameters

pin: the pin to write to.

value: the duty cycle: between 0 (always off) and 255 (always on).

Notes and Known Issues

The PWM outputs generated on pins 5 and 6 will have higher-than-expected duty cycles. This is

because of interactions with the millis() and delay() functions, which share the same internal

timer used to generate those PWM outputs. This will be noticed mostly on low duty-cycle

settings (e.g 0 - 10) and may result in a value of 0 not fully turning off the output on pins 5 and 6.

Experiment component:

1. 1 x 22oΩ resistor

2. 1 x LED

3. 1 x Breadboard

Connect your circuit as the below diagram.