The interface-board MCU manages external IO, power, and peripherals, and communicates with the core board over UART0. Its terminals provide PoE, Wiegand, alarm, and audio wiring.
Part numbers are for datasheet, driver, and debugging reference; follow the BOM and schematic for hardware changes.
The annotated photos are shown below:
Interface Overview
External Interfaces — Exposed on the device enclosure for user access:
| # | Function | Description | Category |
|---|
| 1 | Alarm I/O | Alarm input/output | Product |
| 2 | RS-485 | Serial communication bus | Product |
On-Board Resources — Implemented features:
| # | Function | Description | Category |
|---|
| 3 | IR-CUT Driver | Day/night filter switching | Internal |
| 4 | Light Sensor Detection | ADC ambient light sampling | Internal |
| 5 | IR Light Board Driver | Near/Far-IR PWM | Internal |
| 6 | LENS Driver | SPI lens driver | Internal |
| 7 | System LED | Blue status LED | Internal |
| 8 | Temperature Sensor | ADC temperature sampling | Internal |
| 9 | Bidirectional Reset | SoC resets MCU / MCU resets Processor Board | Internal |
| 10 | RTC | VBAT power-fail retention | Internal |
Internal Reserved Resources — Reserved features, not yet enabled:
| # | Function | Description | Category |
|---|
| 11 | Radar Power Enable | PB0 power control | Internal (Reserved) |
| 12 | Dual-Light Board Driver | White/Red LED PWM | Internal (Reserved) |
| 13 | Fan Driver | 12V fan enable | Internal (Reserved) |
| 14 | Heater | 12V heater enable | Internal (Reserved) |
Debug Interfaces — For development and debugging:
| # | Function | Description | Category |
|---|
| 15 | ST-LINK | SWD debug port | Debug |
| 16 | Debug UART1 | USART1 | Debug |
External Interfaces
Alarm I/O
Alarm input/output on the device enclosure.
| Pin | Function | Note |
|---|
| PB13 | Alarm_IN0 | External alarm input 0 |
| PB14 | Alarm_IN1 | External alarm input 1 |
| PA8 | Alarm_OUT0 | Alarm output 0 (level output) |
| PA9 | Alarm_OUT1 | Alarm output 1 (multiplexed with USART1_TX) |
Note: The MCU exposes 2 Alarm IN pins (PB13/PB14), but the product enclosure connector only routes out 1 Alarm IN.
RS-485
RS-485 serial communication on the device enclosure.
| Pin | Function |
|---|
| PC4 | RS485_TXD3 (Transmit) |
| PC5 | RS485_RXD3 (Receive) |
| PB1 | RS485_EN (Transceive enable) |
On-Board Resources
IR-CUT
IR-CUT day/night filter driver.
| Pin | Function | Note |
|---|
| PB8 | IR_CUT_EN (IR-CUT driver enable) | Supports auto / day / night three-mode switching |
Light Sensor Detection
Photoresistor ADC sampling for ambient light threshold detection, driving automatic day/night mode switching.
| Pin | Function | Note |
|---|
| PA1 | PD_ADC (ADC1_IN1, photoresistor sampling) | Ambient light threshold detection |
Light Board Drivers
The interface board controls external light boards via PWM (independent physical modules connected via connectors).
IR Light Board (Near-IR/Far-IR):
| Pin | Function |
|---|
| PC9 | PWM_Far (Far-IR PWM) |
| PC8 | PWM_Near (Near-IR PWM) |
LENS Driver (AN41908A-VBA)
The MCU SPI1 interface provides the control path for the installed lens module. The AN41908A-VBA entry on this page corresponds to the documented board-level driver device; the product offers AF Lens (44.5° HFOV) or Motorized Zoom (110° HFOV), while the actual lens capabilities, driver device, and firmware controls depend on the specific SKU/BOM. The SoC-side SPI CS1 is also connected to this driver path (default control path), while the MCU side handles lens homing and limit protection.
| Pin | Function |
|---|
| PA5 | SPI1_CLK (SPI clock) |
| PA6 | SPI1_MISO (SPI master in slave out) |
| PA7 | SPI1_MOSI (SPI master out slave in) |
| PA4 | SPI1_CS (SPI chip select) |
| PB3 | LENSPOWER_EN (Lens power enable) |
| PD6 | F_RST (Focus reset) |
| PD5 | Z_RST (Zoom reset) |
| PD4 | RSTB (Master reset) |
| PD3 | PLS2 (Step control 2) |
| PD2 | PLS1 (Step control 1) |
| PD1 | VD_FZ (Vertical drive Focus/Zoom) |
| PD0 | LS_FZ (Limit switch Focus/Zoom) |
System LED
| Pin | Function | Note |
|---|
| PD9 | SYS-LED (System status LED) | Blue, MCU direct control |
Temperature Sensor (LMT87DCK)
| Pin | Function |
|---|
| PB2 | Temp_ADC (Temperature ADC sampling) |
Main Board Reset
MCU controls core processing board reset via PD8. Conversely, the SoC can also reset the MCU via H_GPIO_18 (SN74LVC1G14DCK) (see Core Board).
| Pin | Function |
|---|
| PD8 | POWER_RST (Core processing board reset control) |
RTC
MCU VBAT powered by external supercapacitor to maintain RTC operation, synchronized with core processing board system time.
| Function | Description |
|---|
| RTC Power | VBAT with external supercapacitor |
| Time Sync | MCU RTC synchronized with core processing board |
| Power-Fail Retention | Supercapacitor maintains RTC operation |
Internal Reserved Resources
Radar Power Enable
MCU controls the radar module power switch.
| Pin | Function |
|---|
| PB0 | Radar_EN (Radar power enable) |
Dual-Light Board Driver
| Pin | Function |
|---|
| PB4 | PWM_R (Red light PWM) |
| PB5 | PWM_W (White light PWM) |
| PB6 | R_CTL (Red light switch control) |
| PB7 | W_CTL (White light switch control) |
Fan Driver
| Pin | Function | Note |
|---|
| PB9 | FAN_EN (Fan enable) | 12V |
Heater
| Pin | Function | Note |
|---|
| PA15 | HEAT_EN (Heater enable) | 12V |
Debug Interfaces
ST-LINK
MCU SWD debug port for firmware flashing and online debugging.
| Pin | Function |
|---|
| PA14 | SWDCLK / BOOT0 |
| PA13 | SWDIO |
UART1 (Debug Serial Port)
| Pin | Function | Notes |
|---|
| PA10 | USART1_RX (Receive) | — |
| PA9 | USART1_TX (Transmit) | Mutually exclusive with Alarm_OUT1, only one can be used at a time |
