DVP Pin Mapping & Functional Equivalents

In DVP (Digital Video Port) camera sensors, many pins have synonymous names depending on whether the manufacturer uses industry-standard or proprietary labels.

Standard Protocol Camera Sensor Label Function Description
SDA SIO_D Serial Data: The data line for the I2C-compatible SCCB interface used to configure camera registers.
SCL SIO_C Serial Clock: The clock signal for the I2C-compatible configuration interface.
HSYNC HREF Horizontal Reference: High when a valid row of pixels is being transmitted.
XMCLK / MCLK XCLK External Clock: The master heartbeat (usually 24MHz) provided by the MCU to drive the sensor.

Critical Technical Nuances

1. SCCB vs. I2C (SIO_D / SIO_C)

While SIO_D/C is physically identical to I2C, it often uses the SCCB (Serial Camera Control Bus) protocol.

  • Compatibility: Most modern MCU I2C peripherals work fine, but some older sensors do not generate an "Acknowledge" (ACK) bit.
  • Fix: If your MCU throws an I2C error, try disabling "ACK checking" in your driver code.

2. Timing Reference (HSYNC vs. HREF)

  • HSYNC is technically the pulse between lines.
  • HREF is a "gate" signal that stays HIGH while data is valid on the Y2-Y9 (D0-D7) pins.
  • Wiring: Connect your MCU's HSYNC input directly to the Sensor's HREF pin.

3. The Master Clock (XCLK)

  • The sensor will not respond to I2C (SIO_D) commands until it receives a stable XCLK signal.
  • Pro-tip for Rover V2: Keep XCLK and PCLK traces as short as possible. High-speed clock lines can create EMI that might interfere with your sensitive BMI323 IMU or DRV8701 gate drivers if they are routed too closely.

4. Power Sequencing

  1. Apply Power (DVDD, AVDD, DOVDD).
  2. Start XCLK.
  3. Pulse RESET low.
  4. Begin SIO_D/C configuration.

Can Y0/Y1 be NC?

Yes. This effectively truncates a 10-bit or 12-bit sensor output to 8-bit.

  • Key Technical Rules:

    1. Bit Alignment: You must map the Sensor MSBs to the Processor D-pins.
      • Sensor Y9 -> Processor D7
      • Sensor Y8 -> Processor D6
      • ...
      • Sensor Y2 -> Processor D0
    2. Truncation: Y0 and Y1 are the LSBs (fine detail). Leaving them NC simply discards the lowest 4 levels of pixel data, which is standard for most 8-bit MCU/SoC interfaces.

  • Important Considerations:

    • Register Configuration: You MUST configure the camera sensor (via I2C/SCCB) to output in 8-bit mode (e.g., YUV422 or RGB565).
    • EMI Mitigation: While NC works, terminating with a high-value pull-down resistor can improve signal integrity if you notice noise.
    • Clocking: The PCLK frequency remains identical; ensure your timing constraints in your firmware account for the 8-bit throughput.

  • Comparison Table (10-bit vs 8-bit):

Feature 10-bit (Full) 8-bit (Truncated)
Dynamic Range 1024 levels 256 levels
Compatibility High (Requires 10+ pins) Universal (8-pin bus)
Use Case High-end imaging Navigation/Tracking

ref

- camera-dat

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