AMSAT CubeSatSim STEM Payload Pico firmware v2.0.1
==================================================

WHAT THIS IS
------------
Compiled firmware (UF2) for the Raspberry Pi Pico W on the AMSAT CubeSatSim
STEM Payload board (the Main board, labelled "STEM Payload Board"), version
2.0.1, built from the Arduino sketch stempayload/Payload_BME280_MPU6050_XS.

It first appeared with CubeSatSim release v2.0 (2024-10-22), whose notes list
"New STEM Payload Arduino software for the Raspberry Pi Pico. Includes support
for a serial GPS module and includes a Squelch troubleshooting indicating in
the Serial Monitor for troubleshooting command and control issues." Releases
v2.1 (2025-06-14) and v2.2 (2026-01-28) attach the byte-identical file and
state "No changes to Raspberry Pi Pico code". The Pico reads the payload
sensors (BME280, MPU6050) and serves the STEM Payload data the Raspberry Pi
transmits.

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
----------
The Raspberry Pi Pico W (the release notes: "should work with a Pico or Pico W
board") on the v2.0/v2.1 CubeSatSim STEM Payload (Main) board, used with the
v2.0, v2.1 or v2.2 Raspberry Pi software.

Not for the older Pico-only CubeSatSim port (the v0.x "Pico PCB" firmware),
and not a Raspberry Pi Zero image.

BEFORE STARTING
---------------
  - A computer with a USB port and a micro-USB data cable.
  - Access to the Pico's BOOTSEL button.
  - Raspberry Pi software v2.0 or later on the CubeSatSim's Pi Zero.

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

Payload_BME280_MPU6050_XS.ino.v2.0.1.rpipicow.uf2
    699,392 bytes
    SHA-256 034f97e86cb1ca8ad8d6efd2c8999b50a5483d72fcc58bf04ce9772431713d87
    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 watching the Pico's serial output (Arduino Serial
Monitor or PuTTY); where the firmware prints its version string could not be
confirmed. On the air, the STEM Payload sensor data appears in FoxTelem when
the CubeSatSim transmits FSK or BPSK telemetry.

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: Payload_BME280_MPU6050_XS.ino.v2.0.1.rpipicow.uf2
- Downloaded from:
  https://github.com/alanbjohnston/CubeSatSim/releases/download/v2.2/Payload_BME280_MPU6050_XS.ino.v2.0.1.rpipicow.uf2
- Identical asset (same SHA-256) also attached to releases v2.0 and v2.1.
  GitHub's published asset digest for v2.1 and v2.2 matches.
- Retrieved: 2026-09-18
- Official page: https://github.com/alanbjohnston/CubeSatSim/releases/tag/v2.2
- Status: verified (the project's own GitHub 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/
