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en:iot-open:introductiontoembeddedprogramming2:cppfundamentals:analog_io [2023/07/10 12:06] – external edit (Unknown date) 127.0.0.1 | en:iot-open:introductiontoembeddedprogramming2:cppfundamentals:analog_io [2023/11/23 10:21] (current) – pczekalski | ||
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- | ==== Manipulating analogue signals ==== | + | ====== Manipulating analogue signals ====== |
+ | {{: | ||
The analogue inputs and outputs are used when the signal can take a range of values, unlike the digital signal that takes only two values (//HIGH// or // | The analogue inputs and outputs are used when the signal can take a range of values, unlike the digital signal that takes only two values (//HIGH// or // | ||
- | === Analog input === | + | ==== Analog input ==== |
For measuring the analogue signal, microcontrollers have built-in **analogue-to-digital converter** (ADC) that returns the digital value of the voltage level. Usually, the binary number corresponds to the input voltage, not the value in Volts. The number of bits of the output value depends on the accuracy and internal construction of the converter and usually varies between 8 and 12. | For measuring the analogue signal, microcontrollers have built-in **analogue-to-digital converter** (ADC) that returns the digital value of the voltage level. Usually, the binary number corresponds to the input voltage, not the value in Volts. The number of bits of the output value depends on the accuracy and internal construction of the converter and usually varies between 8 and 12. | ||
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</ | </ | ||
- | The parameter //pin// is the name of the pin whose value is read. | + | The parameter //pin// is the pin's name whose value is read. |
The return type of the function is the integer value. On the Arduino Uno boards, it ranges between 0 and 1023. The reading of each analogue input takes around 100 ms. | The return type of the function is the integer value. On the Arduino Uno boards, it ranges between 0 and 1023. The reading of each analogue input takes around 100 ms. | ||
< | < | ||
- | Not every pin can be used as analogue input. Read the documentation of the chosen development board for details. | + | Not every pin can be used as an analogue input. Read the documentation of the chosen development board for details. |
</ | </ | ||
- | === Analog output === | + | ==== Analog output |
- | Unlike analogue input, the analogue output does not generate varying voltage directly on the pin. In general, it uses the technique known as (//Pulse Width Modulation// | + | Unlike analogue input, the analogue output does not generate varying voltage directly on the pin. In general, it uses the technique known as (//Pulse Width Modulation// |
**analogWrite()** | **analogWrite()** | ||
- | The function // | + | The function // |
The syntax of a function is the following: | The syntax of a function is the following: | ||
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<code c> | <code c> | ||
- | #define LED_pin 3 //the pin number is chosen to support PWM generation | + | #define LED_pin 3 //the pin number is chosen to support PWM generation |
void setup() { | void setup() { | ||
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} | } | ||
- | int value; | + | int value; |
void loop() { | void loop() { | ||
- | value = analogRead(A0); | + | value = analogRead(A0); |
- | value = value >> 2; //it should be converted to the value of the range 0 - 255 | + | value = value >> 2; //it should be converted to the value 0-255 |
analogWrite(LED_pin, | analogWrite(LED_pin, | ||
} | } |