HydroBot: Connecting the Modules

HydroHub is a HydroBot module designed to connect together HydroBot modules in a star topology. The hub provides power and CAN connectivity to a total of eight channels. It has a DC barrel jack for connecting an external power supply, as well as selectable termination for the CAN bus.

HydroHub Features:

• 8 channels for connecting HydroBot modules
• 5.5mm DC barrel jack for power input
• 6-30V input works with 12V and 24V systems
• Selectable 120Ω CAN bus termination resistor
• Power indication LED
• JST-PA series connectors
• Open source design

JST-PA Series Connectors

This design introduces the switch to JST-PA series connectors for HydroBot modules. These connectors, although somewhat bigger and more expensive than the JST-ZH connectors used previously, will allow for lower gauge wiring and much higher currents than before. The new connectors support 22-28 gauge wiring and up to 3A per pin. All new module designs going forward will use JST-PA connectors and existing modules will be updated as part of the next revision cycle. The first module that has been updated to include the new connectors is the AirSense module, which has also added a light sensing feature. Other HydroHub features to note include a constant current driver for the power indication LED to keep brightness consistent over the entire input voltage range, and a CAN bus termination resistor that can be selected using a simple jumper to accommodate the needs of various network topologies.

All source can be found in the HydroBot repository. The BOM and generated gerber files are also included for easy replication.

About Matthew Reed

Matthew is a computer engineer who enjoys designing hardware for embedded control systems. His hobbies include photography, gardening, coffee, and anything DIY.