Analog I/O

Reading A0-A5 with analogRead() (0-1023) and PWM with analogWrite() (0-255), with their settings. More...

Functions
	analogReadResolution (bits)
	Sets the number of bits analogRead() returns.
	analogRead (pin)
	Reads an analogue pin.
	analogWriteResolution (bits)
	Sets the range analogWrite() takes.
	analogWriteFreq (hz)
	Sets the PWM frequency for analogWrite() on pins set up after this.
	analogWrite (pin, value)
	Puts a PWM signal on a pin: a fraction of the time high.

Variables
str	A0 = "A0"
	Analogue pin A0 (RP2040 ADC, 0-3.3 V).
str	A1 = "A1"
	Analogue pin A1 (RP2040 ADC, 0-3.3 V).
str	A2 = "A2"
	Analogue pin A2 (RP2040 ADC, 0-3.3 V).
str	A3 = "A3"
	Analogue pin A3 (MAX11635, 0-2.048 V).
str	A4 = "A4"
	Analogue pin A4 (MAX11635, 0-2.048 V).
str	A5 = "A5"
	Analogue pin A5 (MAX11635, 0-2.048 V).

Detailed Description

Reading A0-A5 with analogRead() (0-1023) and PWM with analogWrite() (0-255), with their settings.

Function Documentation

analogReadResolution()

analogReadResolution

(

bits

)

Sets the number of bits analogRead() returns.

Below 12 bits, analogRead() drops the lowest bits of the reading; above 12 it adds zero bits, which widens the range but adds no detail.

Parameters

bits	1-16. 10 (0-1023) at start-up; 12 (0-4095) is the ADCs' own resolution.

Exceptions

ValueError

bits is outside 1-16.

analogRead()

analogRead

(

pin

)

Reads an analogue pin.

At 10 bits each step is 3.2 mV on A0-A2 and 2 mV on A3-A5, so the two groups give different numbers for the same voltage. Keep A3-A5 at or below 2.048 V. Averaging is set with analog_averaging() in phyduino.py.

Parameters

pin	A0-A5, or 0-5 for A0-A5.

Returns

0-1023 at the default 10 bits. A0-A2: top = 3.3 V. A3-A5: top = 2.048 V.

Exceptions

ValueError	Not an analogue pin.
OSError	The external ADC did not respond (A3-A5).

Example

millivolts = analogRead(A0) * 3300 / 1024  # A0's reading as a voltage

analogWriteResolution()

analogWriteResolution

(

bits

)

Sets the range analogWrite() takes.

For example 10 takes 0-1023, and 16 takes 0-65535.

Parameters

bits	1-16. 8 (0-255) at start-up.

Exceptions

ValueError

bits is outside 1-16.

analogWriteFreq()

analogWriteFreq

(

hz

)

Sets the PWM frequency for analogWrite() on pins set up after this.

Pins already on PWM keep their frequency. Pins next to each other on a PWM slice share one frequency (see pwm() in phyduino.py), so setting up one can change its neighbour's.

Parameters

hz	Frequency in Hz, 8 Hz and up. 1000 at start-up.

analogWrite()

analogWrite	(		pin,
			value )

Puts a PWM signal on a pin: a fraction of the time high.

Pairs of pins share a PWM output; see pwm() in phyduino.py. The signal runs at analogWriteFreq() (1000 Hz at start-up) and keeps going while your code runs, until another analogWrite(), digitalWrite() or pinMode() on the pin. A meter on the pin reads the average: 128 gives about 1.65 V.

Parameters

pin	Pin number (3 is D3) or name ("D3", "A0", LED_BUILTIN).
value	0 (always low) to 255 (always high) at the default 8 bits; values outside the range are clamped.

Exceptions

ValueError

Unknown pin, an analogue-only pin (A3-A5), or the pin shares its PWM output with one already in use.

Example

analogWrite(LED_BUILTIN, 64)  # the LED at about a quarter brightness

Variable Documentation

A3

str A3 = "A3"

Analogue pin A3 (MAX11635, 0-2.048 V).

Analogue only.

A4

str A4 = "A4"

Analogue pin A4 (MAX11635, 0-2.048 V).

Analogue only.

A5

str A5 = "A5"

Analogue pin A5 (MAX11635, 0-2.048 V).

Analogue only.