Install Sidecar Mini (Teensy 4.1)

The Teensy version works together with the Rytm mods. Patch and flash those first (Patch and flash the Rytm).

You need

• A Teensy 4.1 with a USB host cable on its 5-pin host header (soldered pins).
• A micro-USB data cable.
• Optional: a microSD card (FAT32 or exFAT).
• From the Releases page: sidecar-teensy41-<commit>.hex and its .sha256. Optional: the plugins/ folder (the starter user machines).

Wiring

 Analog Rytm MKII                     Teensy 4.1                          computer or USB power
 [USB-B] ---- USB A-to-B cable ----> [host cable, USB-A socket]
                                      on the 5-pin USB host header
                                     [micro-USB] <---- micro-USB cable ---- [USB]

• Plug the Rytm straight into the host cable. Do not use a hub.
• Solder the Teensy 4.1’s USB host header (5 V, D-, D+, GND, shield). Press-fit or unsoldered pins make the host port flaky: the Rytm connects only after a reboot or after many retries (the link comes up at full speed and drops), and the Teensy’s own USB to the computer can drop when the host port’s power switches on. Use a short, good USB cable to the Rytm.
• The Rytm has its own power. The Teensy is powered from its micro-USB port.
• On the Rytm: SETTINGS > SYSTEM > USB CONFIG set to the Overbridge mode. That is the only setting the Sidecar needs: the Rytm’s MIDI port settings (USB MIDI in and out) do not have to be changed for the voices, send effects, user machines or remote pages (tested on hardware). Only STUTTER’s tempo sync and the recorder’s armed mode use the Rytm’s clock and transport over USB (MIDI CONFIG: CLOCK SEND and TRANSPORT SEND).

Load the firmware

Check the file first: shasum -a 256 sidecar-teensy41-*.hex must print the value in the .sha256 file.

Option A: Teensy Loader (the app)

1. Install the Teensy Loader from PJRC: https://www.pjrc.com/teensy/loader.html. It also comes with Teensyduino.
2. Connect the Teensy with the micro-USB cable. Unplug the Rytm from the host cable while you do this.
3. In Teensy Loader: File > Open HEX File, and choose the .hex.
4. Press the white program button on the Teensy. The Loader writes the file and reboots the board.

Option B: the command line

teensy_loader_cli --mcu=TEENSY41 -w -v sidecar-teensy41-<commit>.hex

Press the program button when it says “Waiting for Teensy device”. On Linux, install PJRC’s udev rules first: https://www.pjrc.com/teensy/00-teensy.rules.

To go back, load any other Teensy 4.1 program the same way. The Teensy’s bootloader cannot be overwritten.

SD card (optional)

A FAT32 or exFAT microSD card in the Teensy’s built-in slot. Create /Samples/ yourself; the Teensy creates /.rytm/ on first boot. For recording without PSRAM, use a fast card (A1/A2, U3/V30); takes go to /Recordings.

Folder	What
/Samples/	your samples (WAV), browsable from the Rytm’s sample browser under SIDECAR
/JUNO/, /DX7/	patch banks for the JUNO and 6-OP FM machines (optional)
/.rytm/	the Sidecar’s own state: card index, pools, slot maps (do not edit)
/MACHINES/, /PRESETS/	user machine exports and presets (created when used)

With no card the Teensy still runs. The SIDECAR folder on the Rytm is then empty.

Defaults

• out=tracks: each voice returns on its own track’s channel. The mods expect this.
• notes off: the Rytm’s MIDI notes do not trigger the voices. The mods trigger them.

Both can be changed from the web console, but the defaults are right for the mods.

Starter content

sidecar-content-<version>.zip on the Releases page holds /JUNO/Factory/ (the Juno-106’s 128 factory patches) and /DX7/ (three 32-voice DX7 banks), with a README and the licence notice. Extract it to the root of the Teensy’s microSD card (it only adds files; merge with your folders).

On the Rytm: the sample browser’s SIDECAR folder → JUNO/Factory or DX7 → LOAD TO PROJ adds a patch to the project’s list, and the JUNO or 6-OP FM machine’s PAT knob steps through it.

Starter user machines

The release’s plugins/ folder holds six starter machines as Teensy packages: sc_acid.rmp, sc_wavepad.rmp, sc_metal.rmp, sc_snare.rmp, sc_pluck.rmp, sc_grain.rmp (MIT; check them against SHA256SUMS). Install them from the web console, tab Machines: they go into the Teensy’s own plugin store, and installing waits until the Rytm’s transport is stopped. The Pi’s .a64.rmp files do not load on the Teensy. The console’s Machines tab is in testing on the Teensy.

Which Rytm build

rui1027d (the default) or sfx1021 (without the remote pages). The remote pages work with this firmware (tested on hardware): TRK + YES opens SIDECAR, SYSTEM, SCOPE, the REC page, the LFO page and the voice pages. The Mini has no network, so its SYSTEM page shows no network line; its recorder row shows IDLE, ARM or REC m:ss. Playback and channel picking on the REC page are the Pi’s for now. The first version is based on Analog Rytm MKII OS 1.73. OS 1.74 will be supported after testing.

User machine space on the Teensy

The Teensy has 32 KB of plugin code space. The six starter machines fit together, and so do two (some three) of the smaller NoisePlethora packages; only one of the old large ones (NP VOICES, NP CLUST1, NP CLUST2) fits at a time. When a machine does not fit, the Rytm shows !ROOM (hardware). With PSRAM a second code space takes more (in testing). The Pi has no such limit.

Check that it works

1. Power the Teensy, then plug in the Rytm (with the patched OS).
2. Open the web console in Chrome or Edge and connect. The log shows ob: streaming and MIDI attached.
3. On the Rytm, pick an EXT machine (PLAITS, say) on a track and play it.
4. Open the sample browser: FUNC + SMPL, DOWN, FUNC + YES. SIDECAR appears at the +Drive root.

If something is off, see Troubleshooting, then open a tester report.