AMSAT CubeSatSim Pico STEM Payload firmware v0.42 (beta)
========================================================

WHAT THIS IS
------------
Beta firmware (UF2), version 0.42, released 2023-08-16: "Raspberry Pi Pico
code to run STEM Payload OK software only. Works with the Beta software for
the Pi Zero branch sr-frs-tx." It is the last release of the v0.x numbering
and the first that runs only the STEM Payload role on the Pico; the payload
firmware continued as the v1.3.x betas (payload_pico, then
Payload_BME280_MPU6050_XS) and 2.0.1.

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 acting as the STEM Payload with the Pi Zero beta
software from branch sr-frs-tx (2023). Superseded; kept for owners of boards
and SD cards from that period.

Not for the Pico-only CubeSatSim port (v0.41 and earlier).

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.stempayload.v0.42.uf2
    735,232 bytes
    SHA-256 ca2ef230d5362f49594b9c4d3eff6d0baa4e1c1a3ad8e12525fa0ad6fee73098
    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 give no version display; watch the serial output as above.
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.stempayload.v0.42.uf2
- Downloaded from:
  https://github.com/alanbjohnston/CubeSatSim/releases/download/v0.42/cubesatsim.ino.rpipicow.stempayload.v0.42.uf2
- Retrieved: 2026-09-18
- Official page: https://github.com/alanbjohnston/CubeSatSim/releases/tag/v0.42
- 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/
