The Gemini 335Lg is designed to be compatible with complex multi-device sync scenario. There are two methods that users can choose to HW sync multiple Gemini 335Lg and other devices. One is through the GMSL2 / FAKRA link without using sync cable; the other one is through the 8-pin AUX connector with sync cable which is usually used in USB connections. But Gemini 335Lg can also sync via 8-pin port, as the GPIO map and the sync trigger signal is connected to the same PCBA component inside Gemini 335Lg.
Figure-1 Sync schematic
Gemini 335Lg supports HW sync via GMSL2 or 8-pin cable， but the signal requirement is the same. Sync trigger signal is active in rising edge. Default pulse level is 3.3V and pulse width is required to be ≥ 1ms. Detailed signal requirements can be found in Set up cameras for external synchronization.
Figure-2 Trigger signal reference waveform
- Method 1: Multi-device sync via GMSL2 / FAKRA:
Gemini 335Lg is compatible with NVIDIA ecosystem, such as AGX Orin developer kit & AGX Xavier developer kit. To achieve accurate synchronization, the host should be able to output stable and high-accuracy trigger signal. After the trigger signal is output to the supported deserializer MAX9296A or other compatible one, deserializer and serializer can transmit the signal to MCU by GPIO map via coax cable. The GPIO used is usually MFP10 or MFP7. Taking CTI’s deserializer board JCB002 as an example, the board can generate PWM signal, then signal is transmitted to the camera side.
Users can check the synchronization performance in Orbbec viewer. If JCB002 is the target deserializer board, users should set the camera #1 and camera #2 as “Secondary-synced” in Orbbec viewer, then use the provided script to generate PWM signal from JCB002. In this case, both cameras are used as slave cameras, with the host as the master, to achieve precise multi-device synchronization. When configured properly and without external interference, the synchronization accuracy can reach 1ms.
Under the current technological solutions, Gemini 335Lg only supports multi machine synchronization as a slave and does not support being a master. Only supports multi-device synchronization when the master is the host.
- Method 2: Multi-device sync via 8-pin port:
When using 8-pin port for multi-device synchronization, in order to ensure the quality of the synchronization signal, it is necessary to use it together with a multi-device sync hub. Pin 3 of the sync interface is the trigger signal output pin, Pin 6 is the trigger signal input pin, and Pin 8 is the ground pin. Star synchronization & string synchronization are both supported. For detailed connection methods and precautions, please refer to the document ” Set up cameras for external synchronization.”
