BCON for MIPI Hardware Design Guide#
Identifiers such as D1, CLK, or I2C_SDA refer to the pin names given in your camera topic. You can find your camera topic in the "Models" section.
Data Transmission (D0, D1, D2, D3, CLK)#
BCON for MIPI uses four data lanes (D0 to D3) and one clock line (CLK) to transmit image data from the camera to the image processing unit.
Design Recommendations for Data Transmission#
Printed Circuit Board (PCB)#
- Design the PCB to have a differential impedance of 100 ohms. If this is not possible, make the traces between the connector and the receiver as short as possible.
- Run the differential pair traces as close as possible, but leave a gap of at least three trace widths between the individual pairs.
- Ensure that the two traces of a differential pair have the same length. The difference in length should be less than 150 µm.
- Ensure that the lengths of all pairs don't differ by more than 1.5 mm.
- Avoid vias. Run the traces from the connector to the receiver on a single PCB layer if possible.
- Avoid stubs. Run the traces through the termination resistor's solder pads rather than branching the trace. Even small stubs can cause reflections.
Flexible Flat Cable (FFC)#
- Choose an FFC with a differential impedance of 100 ohms to avoid problems with electromagnetic interference (EMI).
- Keep the cable away from unshielded electric motors, transformers, and unshielded coils.
- If you use an FFC without a ground layer, keep the cable away from materials with a high dielectric loss.
- If you use an FFC with a ground layer, make sure to insert the cable with the ground tab facing down.
- When ordering a custom flexible flat cable, specify the FFC connector (see below) to ensure that the ground tab is in the correct position and the retaining tabs have the correct shape.
- When using a standard flexible flat cable without a ground layer and retaining tabs, keep the cable short and avoid close proximity to other materials. Note that the pull-out force is reduced when using a cable without retaining tabs.
- Basler recommends using the same connectors on the camera and the system side, although other connectors with the same number of pins can be used.
- The order code of the FFC connector of the camera is Hirose FH41-28S-0.5SH(05). This connector is optimized for impedance-controlled flexible flat cables.
- Make sure that the FFC contact pads meet the mechanical specifications of the Hirose FH41 connector to avoid shorting the GND layer and the data lines. For more information, see the FH41 Series connector website.
I²C Configuration Interface (I2C_SDA, I2C_SCL)#
Basler dart BCON for MIPI cameras use the I²C interface to exchange configuration data with the controlling processor.
I²C is an open-collector bus interface with two signal lines, SDA and SCL. Connect these signal lines to the appropriate ports of an I²C controller. Typically, an I²C controller is part of the microcontroller or the System on a Chip (SoC) that you will be using to process the image data.
For more information about I²C, see the I²C-Bus Specification and User Manual.
NOTICE – Voltage outside of the specified range can cause damage.
You must supply camera power that complies with the individual voltage requirements of the BCON for MIPI interface lines:
The nominal voltage for the power supply line (VCC) is 5 VDC.
The nominal voltage for the I²C interface lines (I2C_SDA, I2C_SCL, I2C_ID) is 3.3 VDC.
Design Recommendations for the I²C Interface#
- The voltage level for the I²C bus is 1.8 V. Make sure that the pull-up resistor is connected to 1.8 V.
- The capacitive bus load for a single I²C bus segment is limited to 400 pF. Take into account that long flexible flat cables can significantly contribute to the total bus load. If necessary, use more than one I²C bus or use an I²C bus repeater.
- Choose a suitable pull-up resistor. The resistor value depends on the capacitive load of the I²C bus lines. For determining appropriate resistor values, refer to the I²C-Bus Specification and User Manual.
Power Supply (GND, VCC)#
The camera needs a single 5 VDC power supply. Bad power quality can negatively affect the camera's image quality. However, a properly designed switched-mode power supply, as used to supply a USB port, will yield good results.
Design Recommendations for the Power Supply#
- The power supply should be able to supply 1.5 W per camera. Long cables can cause a significant voltage drop, leading to a higher power consumption.
- Ground noise can cause bad image quality. Make sure that the power supply input on the PCB (VCC and GND) is close to the camera connectors. The processor and the memory should not be placed between the power supply input and the camera connector.
- Provide an extra capacitor directly on the camera connector where the supply voltage is delivered to the camera (e.g., 10 μF MLCC - multi-layer ceramic capacitor). If the power supply produces excessive noise, a low-pass-filter consisting of a capacitor and an inductor can help to reduce the noise.