Difference between revisions of "PineNote"
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(Update concern about CC1 and CC2 being high or low) |
(Rewrite strikethrough section as introduction to paragraph,) |
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This decision requires the PineNote motherboard to be able to detect an AND condition between CC1 and CC2 and connect one of the SOC's UARTs to pins on the USB-C connector. In all other cases, the UART should be disconnected. It also requires the PINE64 Store ship a simple one-sided (no magical flipping here, sorry) connector board which breaks out USB 2.0 and UART. | This decision requires the PineNote motherboard to be able to detect an AND condition between CC1 and CC2 and connect one of the SOC's UARTs to pins on the USB-C connector. In all other cases, the UART should be disconnected. It also requires the PINE64 Store ship a simple one-sided (no magical flipping here, sorry) connector board which breaks out USB 2.0 and UART. | ||
There | There are concerns that cheap USB-C cables have both CC1 and CC2 shorted together to save a wire. This may cause the PineNote to output 3.3v UART to a device that isn't expecting it, assuming the two are plugged together with a nonstandard cable. | ||
There were concerns that checking CC1 and CC2 being pulled high was not strictly to USB-C standard, as detecting them being pulled low is mentioned in the standard. However,h etecting a pull-up condition is all that is required. According to the USB-C spec, 'B.2.4.1.5.1 ("UnattachedDeb.SRC Requirements"), a Debug and Test System (DTS) that is a power source must pull CC1/CC2 up, while the Target System (TS) in Unattached.SNK is supposed to pull them low.' In English, this means that we'd only need to detect a pull-up condition on CC1 and CC2, meaning a logical AND between them is a sane solution. | |||
IRC logs of this discussion can be found at [[PineNote/Debug_Accessory_Mode_Discussion]]. | IRC logs of this discussion can be found at [[PineNote/Debug_Accessory_Mode_Discussion]]. | ||