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101 lines
2.7 KiB
Markdown
101 lines
2.7 KiB
Markdown
---
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search:
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keywords:
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- ADC
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- Analog
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- ADCChannel
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---
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# ADC
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## class ADC – Analog to Digital Conversion
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### Quick Usage Example
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```python
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import machine
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adc = machine.ADC() # create an ADC object
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apin = adc.channel(pin='P16') # create an analog pin on P16
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val = apin() # read an analog value
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```
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### Constructors
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#### class machine.ADC\(id=0\)
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Create an ADC object; associate a channel with a pin. For more info check the hardware section.
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### Methods
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#### adc.init\( \* , bits=12\)
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Enable the ADC block. This method is automatically called on object creation.
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* `Bits` can take values between 9 and 12 and selects the number of bits of resolution of the ADC block.
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#### adc.deinit\(\)
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Disable the ADC block.
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#### adc.channel\(\* , pin, attn=ADC.ATTN\_0DB\)
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Create an analog pin.
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* `pin` is a keyword-only string argument. Valid pins are `P13` to `P20`.
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* `attn` is the attenuation level. The supported values are: `ADC.ATTN_0DB`, `ADC.ATTN_2_5DB`, `ADC.ATTN_6DB`, `ADC.ATTN_11DB`
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Returns an instance of `ADCChannel`. Example:
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```python
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# enable an ADC channel on P16
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apin = adc.channel(pin='P16')
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```
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#### adc.vref\(vref\)
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If called without any arguments, this function returns the current calibrated voltage \(in millivolts\) of the `1.1v` reference. Otherwise it will update the calibrated value \(in millivolts\) of the internal `1.1v` reference.
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#### adc.vref\_to\_pin\(pin\)
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Connects the internal `1.1v` to external `GPIO`. It can only be connected to `P22`, `P21` or `P6`. It is recommended to only use `P6` on the WiPy, on other modules this pin is connected to the radio.
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### Constants
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* ADC channel attenuation values: `ADC.ATTN_0DB`, `ADC.ATTN_2_5DB`, `ADC.ATTN_6DB`, `ADC.ATTN_11DB`
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## class ADCChannel
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Read analog values from internal/external sources. ADC channels can be connected to internal points of the `MCU` or to `GPIO` pins. ADC channels are created using the `ADC.channel` method.
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### Methods
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#### adcchannel\(\)
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Fast method to read the channel value.
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#### adcchannel.value\(\)
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Read the channel value.
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#### adcchannel.init\(\)
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\(Re\)init and enable the ADC channel. This method is automatically called on object creation.
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#### adcchannel.deinit\(\)
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Disable the ADC channel.
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#### adcchannel.voltage\(\)
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Reads the channels value and converts it into a voltage \(in millivolts\)
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#### adcchannel.value\_to\_voltage\(value\)
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Converts the provided value into a voltage \(in millivolts\) in the same way voltage does.
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{% hint style="danger" %}
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ADC pin input range is `0-1.1V`. This maximum value can be increased up to `3.3V` using the highest attenuation of `11dB`. **Do not exceed the maximum of 3.3V**, to avoid damaging the device.
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{% endhint %}
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