4 mandatory pins
USB-OTG also includes a fifth
Data pins are a differential half-duplex signal
Maximum
9 pins
Added an extra 2 pairs of differential TX and RX signals, for full-duplex operation
Maximum
Maximum
Maximum of
| USB PD |
|---|
| Specification | Maximum Voltage | Maximum Current | Maximum Power |
|---|---|---|---|
| USB 2.0 | |||
| USB 3.0 and USB 3.1 | |||
| USB BC 1.2 (Battery Charging) | |||
| USB Type-C 1.2 | |||
| USB PD 3.0 |
Where the USB Type-C 1.2 specification does not require special negotiation, such as with a USB Power Delivery Control Peripheral—the additional current can be simply negotiated with two
This
This would mean that I do not actually require a USB Power Delivery Control Peripheral chip.
I will need to investigate how this implementation handles supplies that are not capable of sourcing the PD power, however.
Although I do not require a PD control chip for this specification, I should not just naively attach pull-down resistors and assume that the source is capable of sourcing
I could either follow the specification and read the voltages at the centre tap of the downstream-facing port (DFP) and upstream-facing port (UFP) using an ADC in my Microcontroller to determine the advertised current capability and subsequently enable/disable a Load Switch, or use a USB-C Configuration Controller IC like the TUSB320 from TI.
Of course, if I select a STM32 microcontroller that has a built-in UCPD, I can simply use that to negotiate for the
According to the STM32 USB PD wiki however, I do not even a UCPD peripheral in this case—I will need to refer to AN5225 to see if this is meaning that they would recommend that I just attach the pull-down resistors without a configuration IC. I will add further notes below under the USB Power Delivery > Implementation heading.
As calculated in Current Amplifier, I will require up to
As noted above, this means that the standard USB Type-C 1.2 power delivery specification would suffice for this project, as it is capable of
Regardless of the final USB power specification, my power input will need to be connected to a dedicated Power Connector, such that I am able to power the board from a capable source whilst simultaneously flashing and debugging application firmware through the Data Connector.
Expanding on the notes above under the USB Power Delivery > USB Type-C 1.2 heading, I see in AN5225 that Chapter 10 is of most interest to me—Type-C with no Power Delivery. In this chapter however, I see that the provided guidance is to simply attach the