ESP32-S3 SmallHD Tally Bridge

32Thirteen Productions LLC | DIT Technical Reference

HTTP tally bridge for SmallHD monitors. Receives HTTP GET requests from Bitfocus Companion (or any HTTP client) and triggers GPI tally via optocoupler. Built on the Waveshare ESP32-S3-ETH with W5500 SPI Ethernet and WiFi fallback.

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Setup & Deployment

First Flash

Flash the firmware once — all configuration is done through the browser after that. No need to edit the sketch per unit.

1. Open tally_light.ino in Arduino IDE
2. Set board to ESP32S3 Dev Module, ESP32 Arduino core v3.x
3. Under Tools → Erase All Flash Before Sketch Upload → Enabled (ensures a clean state)
4. Flash the board

Configure via Web Portal

After flashing, open a browser and go to:

http://tally-light.local/

or use the IP address shown in the serial monitor if mDNS isn't resolving.

From the portal you can set:

• Device Hostname — unique name for this unit (e.g. tally-cam1). Becomes the .local address.
• IP Mode — DHCP or Static. Static reveals fields for IP, Gateway, Subnet, and DNS.
• WiFi SSID & Password — fallback network if Ethernet is not connected.

Hit Save & Reboot — all settings are stored in flash and survive reboots and reflashes.

Deploying Multiple Units

1. Flash all units with the same firmware (no per-unit sketch changes needed)
2. Connect each unit and open http://tally-light.local/ in a browser
3. Set a unique hostname for each unit (e.g. tally-cam1, tally-cam2)
4. Optionally assign a static IP for each unit for reliable Companion integration
5. Use IP addresses in Companion, not .local hostnames — mDNS can be unreliable on managed networks

Factory Reset

To wipe all saved settings and return a unit to defaults, open the web portal and click Reset to Defaults at the bottom of the page. The device reboots as tally-light with DHCP enabled.

Alternatively, enable Erase All Flash Before Sketch Upload in Arduino IDE before reflashing for a full clean state.

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Hardware

Component	Value
Board	Waveshare ESP32-S3-ETH
Ethernet chip	W5500 (SPI)
Tally output pin	GPIO18
Test button pin	GPIO3
Optocoupler	NOYITO 1-channel PC817 module
ESP32 Arduino core	v3.x required
Board selection	ESP32S3 Dev Module

W5500 Pin Mapping

GPIO	Function
GPIO9	W5500 RST
GPIO10	W5500 INT
GPIO11	SPI MOSI
GPIO12	SPI MISO
GPIO13	SPI CLK
GPIO14	SPI CS

Note: GPIO18 is the tally output. If a pin is damaged, change TALLY_PIN at the top of the sketch — GPIO15 is a confirmed working substitute.

Optocoupler Wiring

Input side (ESP32 → Optocoupler):

Optocoupler	ESP32
+	GPIO18
-	GND

Output side (Optocoupler → SmallHD):

Optocoupler	SmallHD RJ45
VCC	3.3V (ESP32)
OUT	GPI active pin
GND	GPI ground pin

Tip: Use an Ethernet screw terminal breakout board (e.g. Poyiccot RJ45 screw terminal) on the SmallHD end rather than cutting a cable. Direct bare-wire connections are unreliable due to the thin 24AWG solid-core conductors in Ethernet cable. The screw terminal block gives a proper mechanical clamp.

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SmallHD OLED 22 GPI Configuration

Setting	Value
PageOS version required	6.x or later
GPI function	Tally Indicator
Polarity	Active High
GPI pin	Pin 7 (not Pin 1)

Important: Pin 1 does not behave correctly for tally on the OLED 22 — use Pin 7. Polarity is Active High. Tally behavior: open circuit = ON, contact closure = OFF. Verified on hardware running PageOS 6.3.1.

Other SmallHD models in a mixed fleet may require different GPI pin and polarity settings. Bench test each model before deployment.

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HTTP API

Endpoint	Method	Description
/	GET	Web config portal
/config	GET / POST	Web config portal (same as /)
/reset	POST	Clear all saved settings and reboot to defaults
/tally/on	GET	Activate tally (GPIO HIGH)
/tally/off	GET	Deactivate tally (GPIO LOW)
/tally/test	GET	1-second tally pulse for testing
/status	GET	Returns firmware version, IP, interface, IP mode, and tally state

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Bitfocus Companion

Use Generic: HTTP GET action.

Button	URL
Record ON	http://<device-ip>/tally/on
Record OFF	http://<device-ip>/tally/off
Test	http://<device-ip>/tally/test
Status	http://<device-ip>/status

Use static IPs and enter them directly in Companion. mDNS .local addresses are convenient for setup but unreliable in production on managed or VLAN'd networks.

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Known Issues

• mDNS (.local) resolution varies by network — always note the IP as a fallback
• With both Ethernet and WiFi active, the ESP32's mDNS stack can be flaky about which interface it advertises on
• SmallHD GPI behavior differs between monitor models — verify pin and polarity on each model before production deployment

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32Thirteen Productions LLC