Flash it¶
The quickest way to put Flow Ctrl on a board: plug it in, open this page in Chrome or Edge (Web Serial — Safari and Firefox can't), press the button, pick the port.
For a Mac (Cmd/Opt on screen, Cmd+A for Select all):
For a Windows PC (Alt/Ctrl on screen, Ctrl+A for Select all — same board, same buttons):
The board shows its version and chord for four seconds at power-up, and any time you long-press the Flow Ctrl title in the top-left corner.
Which board
The prebuilt image is for the USB-C / 2-USB Cheap Yellow Display (ST7789 panel). The original
micro-USB board needs the cyd build — see Firmware & code.
If the port doesn't appear, hold BOOT on the board while plugging it in, then try again. Some boards need a USB-C → USB-A cable rather than C-to-C.
From a terminal instead¶
pip install esptool
# a new board: the full image at 0x0
esptool.py --chip esp32 --port /dev/cu.usbserial-XXXX --baud 460800 write_flash 0x0 flow-ctrl-v0.9.7-cyd2usb-mac.bin
# an update: the app alone at 0x10000 — keeps the Bluetooth pairing
esptool.py --chip esp32 --port /dev/cu.usbserial-XXXX --baud 460800 write_flash 0x10000 flow-ctrl-v0.9.7-cyd2usb-mac-update.bin
On Windows the port is COM3-style and the images are flow-ctrl-v0.9.7-cyd2usb-win.bin /
…-win-update.bin.
Updating keeps the pairing
The full image at 0x0 also blanks the area where the board keeps its Bluetooth pairing, so the
computer's old pairing stops working and you have to remove Flow Ctrl in Bluetooth settings and
add it again. The buttons on this page, and the -update.bin at 0x10000, leave that area alone —
use them for every update.
The image is in the repo under release/, and attached to each GitHub release.
Then¶
Pair it and set the one Wispr shortcut — Getting started.