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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:

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 though this may not always be possible.

    • 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

    • 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 here

General Gender Conventions

The gender for any connectors used on the drone is critical and should not be taken lightly. Each specific connector series may, in rare cases, deviate from this standard though a reason should be cited in architecture document where that connector is defined.

The following convention will be adopted: any electronic source’s output power will have a female connector and any electronic power consumer input power will have a male connector. In this case male refers to the connector with pin like electrical contacts and female as the connector with socket like electrical contacts.

When deciphering connector gender for the purpose of this standard be sure to ignore any plastic shrouding that may be present. Please note that some connector manufacturers have differing definitions of genders which should be ignore for the purpose of ensuring compliance with this standard.

This standard is critical for safety because we want sources which are always live to be hard to accidentally contact (i.e. short) accidentally whereas loads input power is totally safe to be shorted as there is no power source. This standard is adopted by the COTS world as well so for compatibility we keep this standard.

For non-power connectors, data connectors, please refer to the Pixhawk standard mentioned in another section.

For non-gendered power connectors (i.e. Anderson PP45 connectors) they are generally protected in sufficient shrouding and consequently this gender convention is not directly relevant.

Finally, some examples of this to avoid confusion. For examples of electronic source’s power output connectors we have: battery power connectors, ESC leads to the motor & buck/ldo/bec board output power. For examples of electronic load’s power input connectors we have: power distribution board input power, & ESC input power. Another system level super common example is when you want to plug something into the wall (~120VAC & ~60 Hz) (an electrical source) it has female electrical contacts and the thing you’re plugging in (an electrical load) has male contacts.

Because this design decision is so critical, if you are doing assembly on the aircraft and you are not sure be sure to ask for help and clarification. If you are dealing with an edge case, please document it here in the architecture space and even the general cases should be documented (though most are already).

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