Inputs & Outputs / Pins

1. Digital Signals

Digital signals have two possible logical states:

Digital = two states: HIGH or LOW.

2. Setting Up a Digital Pin

Before controlling a digital output, the pin must be configured for the required purpose.

For example, the corresponding output configuration can generate:

pin26 = machine. Pin(26, machine.Pin.OUT)

3. Digital Output

A Digital Output block changes the state of a configured output.

The program can send:

HIGH or: LOW

4. Digital Input

A Digital Input reads the current state of a pin.

The corresponding read operation is:

pin26.value()

The program can then use the returned state with Logic, Control, or Serial Port blocks.

5. Analog Input / ADC

Analog input introduces an important new concept.

Instead of simply distinguishing between HIGH and LOW, the ADC converts an analog signal into a numerical reading that the program can use.

6. Setting Up the ADC

Clu-Blocks Pro creates an ADC associated with the selected pin.

adc2 = machine.ADC(machine.Pin(2))

The adc2 reference can then be used by the other analog-input blocks.

7. ADC Attenuation

The block does not simply select an arbitrary “reference voltage.” The generated MicroPython changes the ADC attenuation setting.

Clu-Blocks Pro generates four possibilities:

adc2.atten(machine.ADC.ATTN_11DB)

or:

adc2.atten(machine.ADC.ATTN_0DB)

This setting changes the ADC configuration used for the incoming analog signal.

8. ADC Resolution

The second ADC configuration block controls the resolution of the analog conversion.

The real available options generate:

adc2.width(machine.ADC.WIDTH_12BIT)

Attenuation and resolution are different settings. Attenuation relates to the ADC input configuration, while resolution determines the number of bits used for the conversion.

9. Reading an Analog Value

After configuring the ADC, the program can obtain the analog reading.

Clu-Blocks Pro generates:

adc2.read_u16() #for 16 bits

or

adc2.read() #for 12,11, 10 y 9 bits

10. PWM Output

PWM stands for:

Pulse Width Modulation

The category provides three related operations:

SETUP → DUTY VALUE → FREQUENCY

Setup PWM

Clu-Blocks Pro generates:

pwm26 = machine.PWM(machine.Pin(26))

The selected pin becomes the PWM output represented by: pwm26

PWM Duty Value

The visible example uses: 0

and Clu-Blocks Pro generates:

pwm26.duty_u16(0)

The value controls the PWM duty setting.

Think of the PWM value as controlling how much of each rapid pulse cycle is active.

This can later be used in applications such as output-level control.

PWM Frequency

The visible example uses: 2000

and generates:

pwm26.freq(2000)

The frequency controls how rapidly the PWM cycles repeat.

So students should distinguish:

• PWM Value → HOW MUCH
• PWM Frequency → HOW FAST THE PULSES REPEAT

11. Interrupts

Interrupts introduce a more advanced way for a program to react to an input.

Instead of repeatedly checking a pin in the normal program flow, an interrupt associates a pin event with a handler function.

Conceptually:

Pin Changes → Interrupt Trigger → Handler Function

RISING

The generated trigger is:

machine.Pin.IRQ_RISING

The event occurs on the transition represented by the RISING trigger.

FALLING

The generated trigger is:

machine.Pin.IRQ_FALLING

The event occurs on the transition represented by the FALLING trigger.

RISING + FALLING

Clu-Blocks Pro can also generate:

(machine.Pin.IRQ_RISING | machine.Pin.IRQ_FALLING)

This configures both transitions as triggers.

The available selections can therefore be documented accurately:

12. Interrupt Function

ACTION

Instructions associated with the interrupt function

Advanced Concept: Interrupts should be introduced after students are comfortable with normal Digital Input and Control blocks.

13. DAC Analog Output

The final group contains the DAC blocks.

DAC means: Digital-to-Analog Converter

This is different from ADC:

• ADC → Analog Input → Digital Value
• DAC → Digital Value → Analog Output

This distinction is worth reinforcing.

Setup DAC

The corresponding setup can generate:

dac25 = machine.DAC(machine.Pin(25))

This creates the DAC output associated with the selected DAC-capable pin.

DAC Output Value

The visible example uses: 0

dac25.write(0)

The numerical value supplied to the block determines the value sent through the DAC operation.

Digital vs. ADC vs. PWM vs. DAC

Students will benefit from seeing these concepts together.

ADC vs. DAC

These two names are easy for beginners to confuse.

ADC

• Analog → Digital
• Sensor → ADC → Program

DAC

• Digital → Analog
• Program → DAC → Output

An easy memory rule is:

ADC brings analog information INTO the program. DAC sends analog output FROM the program.

Quick Guide for Students

• Do I only need ON/OFF? Think Digital.
• Do I want to read a button or digital sensor? Use Digital Input.
• Do I want to turn a digital output ON or OFF? Use Digital Output.
• Do I need to read a changing analog sensor signal? Use ADC / Analog Input.
• Do I need to configure the ADC input characteristics? Use the Attenuation setting.
• Do I need to change ADC conversion resolution? Use 9-bit, 10-bit, 11-bit, 12-bit or 16-bit resolution.
• Do I need a pulse-controlled output? Use PWM.
• Do I need the program to react to a pin transition?  Use an Interrupt.
• Do I need analog output through a DAC-capable pin? Use DAC.

Quick Reference