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I have two different kinds of DIY USB-C connectors...one kind that is rigged to be a "host" USB-C connector (pulled-up with a 56k resistor per spec), and the other is rigged to be a "device" USB-C connector (pulled-down with a 51k resistor per spec).

My question is: when assembling a charging cable that is used to charge a device (e.g. phone) via a wall outlet puck...which end should be "host"? The phone end, or the power outlet end? Just want to make sure I understand this. Thank you so much in advance!

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  • \$\begingroup\$ I think in this context the host end would be the end providing the power. \$\endgroup\$ – Ron Beyer Dec 1 '17 at 0:57
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Type-C cables don't have gender, they are "they", symmetrical :-) They do have a wire CC (communication channel) that conveys who is who between devices.

In simplest basic case (no Power Delivery), if you have both devices with Type-C connectors, one "provider" (charger), and another "consumer" (a phone), the provider should supply proper pull-up resistor on CC pin indicating how much current it can supply. The pull-down on CC wire will be provided by consumer (CC pull down inside the phone). This is the way how a charger tells the phone how much "juice" the phone can take.

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  • \$\begingroup\$ I will see them as gender fluid cables. \$\endgroup\$ – Harry Svensson Dec 1 '17 at 1:55
  • \$\begingroup\$ Thanks for the clarification. This makes sense to me. What happens if you flip that arrangement and put the "provider" connector to the phone and the "consumer" connector to the charger? Is it still able to figure itself out by communicating across the CC? \$\endgroup\$ – rockwell Dec 1 '17 at 3:41
  • \$\begingroup\$ The cable is symmetrical. Unlike various "legacy" hacks, it has no pull resistors in overmolds. All pulls are inside Type-C devices. If you flip ends, phone will pull its end of CC wire down with 5.1k, and the pullup inside the charger will form a voltage divider, so the CC wire will assume certain voltage (depending on charger's pullup value). This voltage holds the information for phone about source power capability. \$\endgroup\$ – Ale..chenski Dec 1 '17 at 5:02

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