Connector Standards
- Daniel Puratich
- Anthony Luo
Context
Originally authored by Daniel Puratich for Competition 2023, has been moved to a general EE standard and is slowly being updated accordingly. The below resources explain the origins:
2025 Competition Architecture Decisions
Bullet connectors aren’t required because we can reverse on the ESC end. We will be labelling the motors and the arms for Pegasus 2 aircraft so using the keyed MT30 connectors for motor phases is the best path forward. They are well rated for the current we pull on Pegasus.
XT90 connectors will be used on the battery and power module connections. Otherwise high current DC wires should be directly soldered. For power wires on XT connectors, refer to https://docs.holybro.com/power-module-and-pdb/power-module/connector-and-wire-rating .
Low voltage signal wires should follow Pixhawk Connector Standard.
2024 Competition Architecture Decisions
MT30s will be used as a quick connect in the 3-phase wires from the ESC at the entrance to the drone arms. This will allow the drone arms to easily be unplugged from the ESC and taken off. They are rated for 15A nominal and 30A peak which is more than the 14.05A drawn by the motor at 80% throttle.
Bullet connectors will be used for 3-phase connections at the motor to allow the polarity change or disconnecting of the motor to be fast and easy. 3.5mm bullet connectors will be able to handle the current load and are the same size used in last years competition.
More General Connector Standards
This section is mostly from 2023 System Architecture so the above standards take precedence.
Gender Decoding
Gender convention WARG will use is the gender defined by the manufacturer for every connector
When the manufacturer does not specify the gender is defined by the metal conductors in all cases. Plastic housing should be ignored when deciphering gender if not specified by manufacturer.
XT series connectors are convenient, common in the hobby world, fairly reliable, and relatively cheap and will therefore be employed for all WARG DC power connections whenever possible.
COTS PCBAs after require solder pad connections which we will accommodate, but breakout to our prioritized connectors whenever possible.
XT60 connectors will be prioritized for any sub 150 A pulsed DC connection
For ESCs and anything smaller this should be prioritized
XT60-F is on batteries and so the XT60-F should be used on any voltage source and XT60-M should be used on any load. This gender convention is also used in the COTS world and keeps things simple.
Manufacturer PN Gender: “-F” is female & “-M” is male
Custom hardware will use XT60PW series connectors and follow the above gender convention.
XT30s will be avoided when possible for simplicity
While XT30s are smaller and meet our current requirements for lots of low voltage loads in order to minimize the amount of connectors we need to stock and use XT30s will not be prioritized when an XT60 can be used.
COTS loads and sources with XT30s will be adapted to XT60 through harnessing
This may change though requires some discussion
XT90 connectors will be used for any greater than 150 A pulsed DC connections
COTS higher current 6S and above batteries often ship with these XT90s and so we will accommodate such a design decision as they are rated for the higher current.
Anti-spark XT90s should be used whenever possible to limit sparks from in-rush condition.
XT90 battery input splitting into ESC and converter connections should be done on a properly specified PCB with XT connections done in harnessing.
AC Mains is not used on any WARG aircraft and therefore a connector will not be specified
No voltage sources exceeding 55 V during nominal continuous operation are to be present on aircraft due to a lack of necessity and safety concerns
ESC BLDC Motor Controller Phase connectors will be specified in the future and require more decisions in the future.
3.5mm banana connections is a solid option from the hobby world, but they can be a pain. Other size banana connections may be used as well on smaller aircraft as we come up with more specific decisions.
Gender Convention: Female on ESCs, Male on motors
The reason for this is stated in “General Gender Conventions” section of this architecture document and was discussed in this conversation.
Anderson Power pole series connectors are promising and have significant use in FRC, but will require validation before we fully adopt them in place of the ol' banana connectors
Gender is not present on these but ideally three different colors are used.
PWM Signal Connections
Should be done with with standard twisted PWM cables. Ideally locking stuff so it doesn’t pull out easily.
Simplest solution is often the best so sticking with these seems ideal.
Gender convention: Male pins on the signal generator and female sockets on the signal receivers.
We will use mechanical locking on the headers, copying how it is done in Vex to lock the PWM connectors into the board they connect to.
Where this is not viable we will defer to hot glue
Other low voltage signal connections
Debug versions should be done on standard 100mil pitch headers and jumpers
Flight versions should copy Pixhawk connectors whenever possible
This is for UART/I2C/SPI/ etc
This means supporting JST GH connectors for lots of low voltage signal connectors
Allows our hardware to integrate better with COTS hardware.
Specific components will follow manufacturer recommended connectors if we for sure want to support it
i.e. the VectorNav VN-300 has it’s own connector we should just use since we are going to use this component on our system for sure!
If all the above do not offer adequate specification for a low voltage signal connector we will defer to automotive and marine standards and document her