03 Flash the main firmware

Finished-unit users can skip this page: the factory has flashed and verified the firmware. Only redo this for firmware upgrades or after modifying the code. Customers use the prebuilt image (3.1, no PlatformIO); developers build from source (3.2).

3.1 Flash the prebuilt image (recommended for customers)

1. Make sure you have firmware/releases/sr_support_b_ptk_factory.bin (checksums in SHA256SUMS next to it);

2. Enter download mode: hold BOOT, tap RST, release BOOT;

3. Flash it (tool setup on page 02, section 2.4; run these commands in the SR-Support folder with .venv activated):

   • Windows GUI: Flash Download Tool → ESP32-S3 → load the bin at 0x0 → START;

   • Windows / Linux / macOS command line:

     python -m esptool --chip esp32s3 -p COM27 -b 460800 write_flash 0x0 firmware/releases/sr_support_b_ptk_factory.bin

4. Press RST when done and read the log as in 3.3.

For flashing / serial debugging you can power the ESP32 from USB and leave the 5 V supply to the servos only (the two power options are in page 04, section 4.4).

The command is identical on Windows / Linux / macOS; only the port changes: COM27 on Windows, /dev/ttyACM0 on Linux, /dev/tty.usbmodem* on macOS. Flash Download Tool is Windows-only; use the esptool command line elsewhere.

Assembly centering needs no second image: after flashing this one, power up - both servos drive to the firmware zero (1681 / 1456 µs) - then power off and install the horns (page 04, section 4.2). Optionally send e to put them at the 1520 µs electrical center first (equivalent).

3.2 Build and flash from source (developers)

Environment: page 02, section 2.5. Project: firmware/sr_support_b_ptk/ (environment ptk7452).

# Build
pio run -d firmware/sr_support_b_ptk

# Flash (replace COM27 with your port)
pio run -d firmware/sr_support_b_ptk -t upload --upload-port COM27

Run these in the SR-Support folder with .venv activated (page 02, section 2.3); they are identical on all three platforms - replace COM27 in --upload-port with your port. Close anything holding the serial port (serial monitor, tools/hw_monitor.py) before flashing, otherwise you get could not open port / Access is denied.

A successful build uses about RAM 56% and Flash 30% (WiFi + web server included; earlier builds without WiFi were about 7% / 12%).

3.3 Serial monitor

pio device monitor --rts 0 --dtr 0 -b 115200 -p COM27

(Same on all three platforms; replace COM27 with your port.)

Windows GUI serial assistant (optional): UartAssist from 野人家园 (free, single exe, Windows only). Official page https://cmsoft.cn/resource/101.html, official download entry https://cmsoft.cn/resource/download/101. Select the COM port, 115200, 8N1, no flow control, enable "send newline"; watch the boot log/telemetry in the receive pane and type commands in the send box. Download it from the official link only (third-party sites often bundle adware); do not commit the exe to this repository.

Linux / macOS serial viewers (pick one):

• Preferred: the pio device monitor command above (installed with the project, cross-platform);
• Lightweight CLI: python -m serial.tools.miniterm /dev/ttyACM0 115200 (/dev/tty.usbmodem* on macOS; quit with Ctrl-]); the built-in screen /dev/ttyACM0 115200 also works (quit with Ctrl-A, then K);
• GUI: CoolTerm (free, Windows/macOS/Linux, official site https://freeware.the-meiers.org); on Linux you can also sudo apt install cutecom.

On Linux add your user to the dialout group: sudo usermod -aG dialout $USER, then log out and back in.

After opening the port, if the board was just powered or you pressed RST you will see the boot log first; if not, press RST once. After reset you should see:

IMU version 1.1.2
autorun on: get-up waits for a fall
up ... | w ... | q ... | qd ... | run

3.4 Serial commands (115200)

Type every command into the send box of the serial monitor/assistant and press Enter (enable "send newline" in UartAssist); the m command needs a space and two values, e.g. m 0.5 0.

Command	Function
g	Start/continue running (this build autoruns; usually not needed)
s	Stop the executor, hold the last target
x	Emergency release: detach PWM; re-arm with r
r	Re-initialize PWM and center
t	Servo self-test (small motion)
c	Calibrate gyro + accel zero offsets (robot must STAND LEVEL and still; stored in NVS)
m <q1> <q2>	Manual joint targets in rad
1/2	Manual shoulder ±0.5 rad
3/4	Manual elbow ±0.5 rad
0	Manual neutral
l	3 s 50 Hz fast log
k	Print both servo center pulse widths
o / p	Shoulder center ±10 µs trim
z	Encoder-style zero: current pose becomes q=0 for both joints; prints the new pulses (RAM only; see page 05)
e	Electrical center (optional): both servos to 1520 µs for mounting the horns at the electrical center; the usual way is to power up to the firmware zero and mount there (see page 04, 4.2)
d	Toggle the 50 Hz twin stream (MuJoCo twin; same switch on the status page)
w	Toggle WiFi (hotspot + status page/provisioning, see page 08)
v / b	Flip shoulder / elbow sign
i / j	Flip IMU X / Y sign
h	Stand-homing toggle (legacy policy path)
a	Legacy scripted get-up test mode

3.5 Power-on behavior

The firmware defines AUTORUN_ON_BOOT: after power-up the executor waits for the robot to be fully down and still for 0.5 s, then starts automatically - no g needed. Power up with the robot upright.

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