// quick start
This page takes a RadioSonic Rev A board from the box to a working dsp> prompt on a Windows PC, without installing a compiler or a development environment. It takes about ten minutes, and most of that is downloading the tool.
This is a single combined image containing the bootloader, the partition table and the application, so it is written in one piece starting at address 0x0. It is built for the Rev A board, whose silkscreen reads SPL-RS-01-A.
| Item | Notes |
|---|---|
| RadioSonic Rev A board | The board shipped with your course. |
| USB-C data cable | The cable from your cable kit. Some phone charging cables carry power only, and the board will light up but never appear on the PC. |
| Windows 10 or 11 PC | The Flash Download Tool runs on Windows only. On macOS or Linux, use the command line method further down this page. |
| Flash Download Tool | Espressif's free programming utility, version 3.9 or later. It needs no installer: unzip it and run the .exe inside. |
| Firmware image | The .bin file above. |
Before you flash anything, confirm the file arrived intact by comparing its SHA-256 checksum with the one listed above. Open a Command Prompt in the folder that holds the file and run:
certutil -hashfile RadioSonic_RevA_0.9.1-90-g74a0239.bin SHA256
The long hexadecimal string it prints should match the SHA-256 line in the download box exactly. If it does not, delete the file and download it again.
First make sure the board is switched on: the small slide switch SW8 on the bottom edge of the board must be to the left. With SW8 to the right the board is unpowered and will look dead.
The ESP32-S3 only accepts new firmware while it is in its built-in download mode. The two push buttons you need, SW2 (BOOT) and SW1 (RESET), sit immediately to the left of the metal WROOM module. Use whichever of these methods suits the state of your board:
| Method | How |
|---|---|
| Buttons (always works) | Connect the USB-C cable. Press and hold SW2 (BOOT), press and release SW1 (RESET), then release SW2. |
| Console command | If the board is already running RadioSonic firmware and you have its console open, type bootloader and press Enter, then close the terminal program so it releases the port. |
Either way, the board reappears in Windows as USB JTAG/serial debug unit. Open Device Manager, expand Ports (COM & LPT), and note the COM number next to that entry, because you will need it in the next step.
A board that is still running the factory test image, which shows four RGB LEDs breathing green, already appears as the USB JTAG/serial debug unit and can usually be flashed without pressing any buttons. If the tool fails to connect, fall back to the button method.
Unzip the Flash Download Tool and run flash_download_tool_3.9.x.exe from the extracted folder. Windows may warn that the program is from an unrecognised publisher; it is Espressif's own tool, and you can choose More info and then Run anyway. A small window then asks for three settings:
| Setting | Choose |
|---|---|
| ChipType | ESP32-S3 |
| WorkMode | Develop |
| LoadMode | UART (the USB port on the board shows up as an ordinary COM port, so UART is correct even though you are using a USB cable) |
Click OK and the main download window opens.
In the main window, fill in the first row of the file list and the settings below it as follows:
| Field | Value |
|---|---|
| File (first row) | Click the ... button and select RadioSonic_RevA_0.9.1-90-g74a0239.bin. |
| Address (after the @) | 0x0 |
| Row checkbox | Ticked. Leave every other row empty and unticked. |
| SPI SPEED | 80MHz |
| SPI MODE | DIO |
| COM | The COM number of the USB JTAG/serial debug unit from step 2. |
| BAUD | 921600 |
Recent versions of the tool read SPI SPEED and SPI MODE from the image and grey those fields out. If they are greyed out, leave them as they are.
Click START. The status box shows Download while the progress bar fills, and changes to a green FINISH when the image has been written and verified. This takes well under a minute.
Flashing this image clears any settings you have saved on the board, including Wi-Fi credentials and saved presets, and the board starts again with its default configuration. Recordings stored in the board's audio area are not touched.
The chip stays in download mode after the tool finishes, so press SW1 (RESET) once, or slide SW8 to the right and back to the left. Close the Flash Download Tool as well, so it lets go of the COM port.
The RadioSonic firmware runs its console on a different USB interface from the one used for flashing, so a few seconds after the reset Windows removes the USB JTAG/serial debug unit and adds a new port, listed in Device Manager as USB Serial Device with its own COM number. That new port is the one to open.
Connect to it with any serial terminal, such as PuTTY or the serial monitor in VS Code, using these settings:
| Setting | Value |
|---|---|
| Port | The new USB Serial Device COM port |
| Speed | 115200 (the port is native USB, so any value works, and 115200 is the conventional choice) |
| Flow control | None. This one matters, because the console will not respond with hardware flow control turned on. |
Press Enter and you should see the dsp> prompt. Try these commands to confirm everything is working:
ver # firmware version status # DSP mode, input, gains, SD card, Wi-Fi and load meter help # every console command, one line each
The version reported by ver should match the version listed in the download box at the top of this page.
Once the board is running RadioSonic firmware you do not need the buttons to update it. Open the console, type bootloader, close the terminal, and the board comes back as the USB JTAG/serial debug unit, ready for step 4. The button sequence from step 2 remains the dependable fallback whenever a board does not respond.
The Flash Download Tool is Windows only, but Espressif's command line tool esptool does the same job on any operating system with Python 3 installed. Put the board in download mode as in step 2, then install esptool and write the image:
python3 -m pip install esptool python3 -m esptool --chip esp32s3 -p PORT -b 921600 write_flash 0x0 RadioSonic_RevA_0.9.1-90-g74a0239.bin
Replace PORT with the board's serial device, which is usually /dev/cu.usbmodem* on macOS and /dev/ttyACM0 on Linux. To check the download first, use shasum -a 256 on macOS or sha256sum on Linux. The same esptool command also works on Windows with COM followed by the port number in place of PORT. Afterwards, continue from step 5.
| What you see | What to do |
|---|---|
| No LEDs and nothing in Device Manager | Check that SW8 is to the left. Then try a different cable, since a charge-only cable powers nothing useful on the data side. |
| The board connects and disconnects repeatedly | The board has no valid firmware to run, so it keeps restarting. Use the button sequence from step 2, which holds it still in download mode. |
| The tool stops at sync or reports a connection failure | The board is not in download mode, or another program has the port open. Close any terminal, repeat the button sequence, and press START again. |
| FINISH appears but no new COM port shows up | Press SW1 (RESET). The chip stays in download mode until it is reset. |
| The console port opens but nothing appears | Set flow control to None, close and reopen the port, and press Enter. Some terminals open the port before Windows has finished setting it up. |
If you are still stuck, write to info@sigprolabs.com with what the tool shows and what the LEDs are doing, and we will sort it out with you. Students enrolled in a course can also ask in the course Q&A forum.