RP2040 Assembly Language Programming

Learn to program the Raspberry Pi Pico’s dual ARM Cortex M0+ CPUs in Assembly Language. The Pico contains a customer System on a Chip (SoC) called the RP2040, making it the Foundation’s first entry into the low-cost microcontroller market. The RP2040 contains a wealth of coprocessors for performing arithmetic as well as performing specialized I/O functionality. This book will show you how these CPUs work from a low level, easy-to-learn perspective.

There are eight new Programmable I/O (PIO) coprocessors that have their own specialized Assembly Language supporting a wide variety of interface protocols. You'll explore these protocols and write programs or functions in Assembly Language and interface to all the various bundled hardware interfaces. Then go beyond working on your own board and projects to contribute to the official RP2040 SDK. Finally, you'll take your DIY hardware projects to the next level of performance and functionality with more advanced programming skills.

WHAT YOU'LL LEARN

* Read and understand the Assembly Language code that is part of the Pico’s SDK


* Integrate Assembly Language and C code together into one program


* Interface to available options for DIY electronics and IoT projects



WHO THIS BOOK IS FOR

Makers who have already worked with microcontrollers, such as the Arduino or Pico, programming in C or Python. Those interested in going deeper and learning how these devices work at a lower level, by learning Assembly Language.

STEPHEN SMITH is a retired Software Architect, located in Gibsons, BC, Canada. He's been developing software since high-school, or way too many years to record. Since retiring he has pursued Artificial Intelligence programming, earned his Advanced HAM Radio License and enjoys mountain biking, hiking, and nature photography. He continues to write his popular technology blog at smist08.wordpress.com. Chapter 1: How to Set Up the Development Environment

About the Raspberry Pi Pico

About the Host Computer

How to Solder and Wire

How to Install Software

A Simple Program to Ensure Things are Working

Chapter 2: Our First Assembly Language Program

About the ARM Processor

Computers and Numbers

CPU Registers

ARM Instruction Format

RP2040 Memory

About the GCC Assembler

Flashing LEDs in Assembly Language

Chapter 3: How to Build and Debug Programs

CMake

GNU Make

Print Statements

GDB

Chapter 4: Loading and Adding

Negative Numbers

Little Endian Format

How to Shift and Rotate

MOV/MVN

ADD/ADC

SUB/SBC

Chapter 5: How to Controll Program Flow

Unconditional Branch

About the CPSR

Branch on Condition

About the CMP Instruction

Loops

If/Then/Else

Logical Operators

Design Patterns

Chapter 6: Thanks for the Memories

How to Define Memory Contents

How to Load a Register

PC Relative Addressing

How to Load from Memory

How to Index Through Memory

How to Store a Register

Hardware as Memory

Introduction to DMA

Chapter 7: How to Call Functions and Use the Stack

The Stack

Branch with Link

How to Nest Function Calls

Function Parameters and Return Values

How to Manage the Registers

Summary of the Function Call Algorithm

Stack Frames

Chapter 8: Interacting with C and the SDK

How to Call C Routines

How to Call Assembly Routines from C

How to Deal with Inline C Routines

How to Use SDK Header Files

Chapter 9: How to Program the Built-in Hardware

The GPIO Pins

Analog to Digital

PWM

Chapter 10: How to Set and Catch Interrupts

Overview

How to Create an Interrupt Handler

Timers Example

Chapter 11: How to Initialize and Interact with Programmable I/O

Overview

SDK Support

PIO Instructions

How to Control Timing

Examples

Chapter 12: How to Connect Pico to IoT

Connectivity Options

Using a UART or I2C

Internet Basics

Security

Chapter 13: Multiplication, Division and Floating Point

Multiplication Coprocessor

Division Coprocessor

Interpolation

Floating Point Library

Chapter 14: Multiprocessing

Using Both CPU Cores

How to Synchronize and Share Resources

Audience: Intermediate