Stps web flasher
Flash firmware onto the J&OT Stps eurorack module over USB — nothing to install.
This browser can’t talk to USB devices.
WebUSB is required — use Chrome, Edge, or another Chromium-based
browser. Firefox and Safari won’t work.
1Put the module in bootloader mode
- Connect a USB cable between the module and this computer.
- Hold the BOOT button — one of the two hidden tactile buttons on the module’s PCB.
- While holding it, power the module on (or tap the other hidden button, RESET). Then release.
2Pick a firmware
Using the control mapper
It verifies the firmware’s assumed jack/LED/pin mapping against the real panel. It starts as soon as the module leaves the bootloader — have rack power on and watch for four things:
- LED chain sweep (first ∼3 s): each LED lights white for 0.3 s in chain order. If the walk runs Pattern, Clk, M1, O1, M2, O2, M3, O3, M4, O4, Accent, the assumed order is right — otherwise write down the order you saw.
- Inputs: patch a high gate into each M jack and Clk — the LED next to that jack should light green while the gate is high. A different LED lighting means the jack→IN numbering is off.
- Outputs: the outputs take turns, 2 s each, pulsing at 4 Hz while the matching LED blinks white. Patch each O jack and Accent somewhere audible and note which jack actually pulses during each LED’s turn.
- Extras: the Pattern LED’s brightness follows the Pattern CV input; the rear DIP switches light the Accent LED red (SW1) or blue (SW2) while ON (lit when OFF means the active-low assumption is flipped).
- Reflash gesture: with rack power connected, patch high gates into any 3 of the 4 M jacks and hold ~3 s — the module resets straight into the bootloader for the next flash, no buttons needed. Unpatch one to cancel.
3Flash
Serial console
Troubleshooting
- Nothing in the device picker: the module isn’t
in bootloader mode — redo step 1. The picker only lists devices
that identify as
STM32 BOOTLOADER. - Windows — device shows an error or never appears: the bootloader needs the generic WinUSB driver. Run Zadig once, pick STM32 BOOTLOADER, install WinUSB. (If STM32CubeProgrammer installed its own driver, replace it the same way.)
- Linux — “Access denied”: your user
needs permission for the device. Quick fix:
sudo chmod a+rw /dev/bus/usb/<bus>/<dev>, or add a udev rule for0483:df11. - Flash succeeded but the module seems dead: tap the hidden RESET button or power-cycle. If you were holding BOOT the whole time it re-entered the bootloader.