source

pico_ada_c04_pwm

1.7.0

Chapter 4: Analog LED with PWM

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1.7.0

Building smooth breathing LEDs and flowing light bars with hardware PWM on the Raspberry Pi Pico using Ada. From jittery duty cycles to perfect linear dimming - guided by the Voltcraft MSO-5102B oscilloscope and a deep dive into PWM slice mapping on both Pico 1 and Pico 2.

In this chapter we create a reusable Pico.Analog package for PWM-based analogue output. We start with a classic breathing light, then move on to a flowing light bar. Along the way the MSO-5102B reveals the real behaviour of our code, and we discover (and fix) a subtle bug in the experimental RP2350 HAL.

Contained in Chapter 04 are:

  1. Pwm - Original PWM sample from Jeremy Grosser
  2. sketch_04_1_breathing_light - Chapter 4.1 Blink internal LED
  3. sketch_04_2_flowing_light_2 - Chapter 4.1 Project Meteor Flowing Light

Read the full tutorial at Chapter 4: Analog & PWM, GNATdoc documentation, SourceForge repository

Authors
Martin Krischik <krischik@users.sourceforge.net>
Maintainers
Martin Krischik <krischik@users.sourceforge.net>
Maintainer profiles
@krischik
Licenses
GPL-3.0-or-later
Website
https://pi-ada-tutorial.sourceforge.io/pico_ada_c04_pwm
Release archive
sourceforge.net/projects/pi-ada-tutorial/files/Alire/pico_ada_c04_pwm-1.7.0.tgz
Tags
raspberry, pi, pico, rp2040, tasking, light-tasking, ada2022, embedded
Executables
pwm, sketch_04_1_breathing_light, sketch_04_2_flowing_light_2
Manifest
index/pi/pico_ada_c04_pwm/pico_ada_c04_pwm-1.7.0.toml
Build and platform metadata 3 fields
Build switches
{
  "*": {
    "ada_version": [
      "-gnat2022"
    ]
  },
  "development": {
    "compile_checks": "Warnings",
    "contracts": "Yes",
    "runtime_checks": "Overflow"
  },
  "release": {
    "compile_checks": "Warnings",
    "contracts": "No",
    "runtime_checks": "Default"
  },
  "validation": {
    "compile_checks": "Warnings",
    "contracts": "Yes",
    "runtime_checks": "Everything"
  }
}
Configuration
{
  "values": {
    "light_tasking_rp2040": {
      "Board": "rpi_pico",
      "Max_CPUs": 2
    },
    "rp2040_hal": {
      "Interrupts": "bb_runtimes",
      "Use_Startup": false
    }
  }
}
Additional origin data
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  "hashes": [
    "sha256:4182587d55e37a120ec6409b8938672f30fa20771374054b7f8da3cc463e4194",
    "sha512:62f2aaca3994888a5e7af969f53a5a4d65720332e30c9dc5d30ce1ef76f2afffadaccb5da3cd18025614d7f1c3914eba6a0052a561147c1a7aa321de71be0b98"
  ]
}