AMSAT CubeSatSim Pico port firmware v0.41 (beta)
================================================

WHAT THIS IS
------------
Beta firmware (UF2), version 0.41, released 2023-04-16: "a beta release of the
CubeSatSim code ported to the Raspberry Pi Pico for the v0.3 and later Pico
PCB." In this port the Pico runs the whole simulator; no Raspberry Pi Zero is
used. It is the last release of that line (v0.1 of 2022-07-28 through v0.41).

New in v0.41 (release notes): if the clock generator is not found on I2C bus
1, bus 2 is tried (jumpers JP6, 11, 12 and 13 on Pico PCB v0.5 and later put
the Adafruit Si5351 connector J6 on bus 2); the LEDs blink at power-up instead
of 10 seconds later, including the Pico's built-in LED; the serial prompt
timeout is doubled from 20 to 40 seconds. It transmits on 434.9 MHz, or
434.875 MHz with the offset option 'O'.

The CubeSatSim software is released under the GNU General Public License
version 3 (the repository's LICENSE file, formerly gpl.txt). The source of
this firmware is in the repository at the release tag named in PROVENANCE. The
board designs are separately licensed CC-BY-NC-SA by AMSAT.

APPLIES TO
----------
A Raspberry Pi Pico or Pico W on the CubeSatSim Pico PCB, v0.3 or later
(https://github.com/alanbjohnston/CubeSatSim/tree/pico/hardware/pico/).

NOT for the STEM Payload board of the Pi-Zero-based CubeSatSim (v1.3.x /
v2.x); those use the STEM Payload firmware.

BEFORE STARTING
---------------
  - A computer with a USB port and a micro-USB data cable.
  - Access to the Pico's BOOTSEL button.

CONTENTS OF THIS ZIP
--------------------
The zip published on fubsypoly.com wraps the vendor file byte-for-byte,
unmodified.

cubesatsim.ino.rpipicow.v0.41.uf2
    1,020,928 bytes
    SHA-256 b0467bce1d792fb255ad79d7a77b4965a51d8dba27bb115a4916c6acbb725a14
    UF2 firmware image for the RP2040 (Raspberry Pi Pico).
README.txt
    This file.
SHA256SUMS
    SHA-256 checksums of the files above.

INSTALLATION
------------
 1. Plug the Pico into a computer through the Pico's own micro-USB port
    while holding down the white BOOTSEL button on the Pico.
 2. The Pico mounts as a USB drive named RPI-RP2.
 3. Drag (copy) the .uf2 file from this zip onto the RPI-RP2 drive. The
    Pico reboots into the new firmware when the copy completes and the drive
    disappears.
 4. Optionally open the Pico's USB serial port in the Arduino IDE Serial
    Monitor or a terminal program such as PuTTY to watch the log and make
    configuration changes.

Steps 1-4 follow the project's release notes. The release notes do not give
a baud rate for the serial log; this could not be confirmed.

VERIFYING
---------
The release notes describe the serial log and the power-up LED blinking; where
the version string is printed could not be confirmed.

IF SOMETHING GOES WRONG
-----------------------
  - The RP2040's BOOTSEL USB bootloader is in the chip's mask ROM, so a
    failed or interrupted copy is recovered by holding BOOTSEL, reconnecting
    and copying the .uf2 again.
  - If RPI-RP2 does not appear, the cable is probably charge-only; use a
    data cable.
  - Kits ship with the Pico already programmed; reflashing is needed only
    to update or to recover.

DOWNGRADING
-----------
Possible: any release's .uf2 can be copied onto the Pico in BOOTSEL mode in
the same way, older or newer. Match the firmware to the board and to the
Raspberry Pi software version it is meant to run with (see APPLIES TO).

PROVENANCE
----------
- File: cubesatsim.ino.rpipicow.v0.41.uf2
- Downloaded from:
  https://github.com/alanbjohnston/CubeSatSim/releases/download/v0.41/cubesatsim.ino.rpipicow.v0.41.uf2
- Retrieved: 2026-09-18
- Official page: https://github.com/alanbjohnston/CubeSatSim/releases/tag/v0.41
- Status: verified (the project's own GitHub pre-release, unmodified)

MORE INFORMATION
----------------
  - CubeSatSim deep dive: https://radios.fubsypoly.com/cubesatsim/
    (build and software loading: vol-3; operation and modes: vol-5)
  - Project releases: https://github.com/alanbjohnston/CubeSatSim/releases
  - Project wiki: https://github.com/alanbjohnston/CubeSatSim/wiki
  - Project site and downloads: https://cubesatsim.org/download/
