Difference between revisions of "PineNote"

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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.

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 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. This seems unfounded (or not enough of a problem to worry about on a large scale), since the USB-C specification states in section B.2.3.1, "The general concept for setting up a valid connection between a DTS and TS is based on being able to detect the typical USB Type-C termination resistances. However, detecting a Debug Accessory Mode connection requires that both CC pins must detect a pull-up (Rp) or pull-down (Rd) termination. A USB Type-C Cable does not pass both CC wires so a receptacle to receptacle Debug Accessory Mode connection"

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, detecting 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.

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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.
-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 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. This seems unfounded (or not enough of a problem to worry about on a large scale), since the USB-C specification states in section B.2.3.1, "The general concept for setting up a valid connection between a DTS and TS is based on being able to detect the typical USB Type-C termination resistances.  However, detecting a Debug Accessory Mode connection requires that both CC pins must detect a pull-up (Rp) or pull-down (Rd) termination.  A USB Type-C Cable does not pass both CC wires so a receptacle to receptacle Debug Accessory Mode connection"
 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, detecting 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.

Difference between revisions of "PineNote"

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