Raspberry Pi Pico

Random Questions About Raspberry Pi Picos

by Professor Petabyte

Random Questions & Answers

There are some topics which whilst worthy of mention, do not warrant a whole page. This page is a variety of such Raspberry Pi specific Q&As.

If using one or more of the ADC (Analogue-to-Digital-Converter )pins on a RPi Pico, can the AGND ground pin be used for all three ADCs at the same time?

Yes, on the Raspberry Pi Pico, you can and should use the AGND (Analog Ground) pin as the common ground for all three ADC inputs (ADC0, ADC1, and ADC2) simultaneously.

Here's why:

• AGND is internally connected to GND, but it is routed to be as noise-free as possible for analog operations.
• It's specifically intended to be used as the reference ground for analog inputs, reducing digital switching noise from interfering with ADC readings.

Practical Advice:

• Connect the ground side of all sensors or analog voltage sources feeding into ADC0, ADC1, and ADC2 to AGND.
• Only one AGND pin exists on the Pico, but it serves as the common analog reference for all ADC inputs.

Summary:

Yes - you can use AGND for all three ADCs at the same time, and you should for better accuracy.

Why are there so many GND pins on a RPi Pico?

The Raspberry Pi Pico has multiple GND (ground) pins for several practical electrical and design reasons:

Ease of Access (Physical Layout):

• With 40 pins on the Pico, having several GND pins distributed along both sides makes it easier to connect components no matter where they are on your breadboard or PCB.
• Reduces the need to run long jumper wires just to reach a ground pin.

Current Return Paths:

• All electrical signals need a return path to ground.
• More GND pins help distribute the return currents and reduce voltage drops or ground bounce, especially when multiple devices are powered.

Power Stability:

• Ground is part of the power supply system. Multiple GND pins help ensure a stable and low-resistance ground connection, which is essential for:
  • Noise-sensitive analog components
  • High-speed digital signals
  • Consistent power delivery

Analog vs Digital Separation:

• The Pico includes a dedicated AGND (Analog Ground) pin to provide a cleaner ground reference for ADC operations. Keeping analog and digital grounds separate (at least in layout) helps reduce noise coupling into analog measurements.

Redundancy:

• Multiple ground pins offer redundancy — if one gets disconnected or overloaded, others can maintain grounding.

Summary:

Multiple GND pins improve convenience, signal integrity, power stability, and analog accuracy - all critical for reliable microcontroller operation.

Can a Pico only run on USB power (5v)?

No, there are many options, some more or less than 5v. This question is answered fully on the page Power to the Pico, but the following table give a quick summary.

Power Feed Summary