70.6.2.1 Sink Detection at Power Source

Each of the possible values—Rd or zOPEN—for the pull-down resistor on CC1 and CC2 of the sink specified in the Universal Serial Bus Type-C Cable and Connector Specification (see Reference Documents) corresponds to one of the respective VRd or VOPEN voltage detection values at the source as shown in the figure below.

Figure 70-4. TCPC_UPC.TCIDCTSEL Values of CCx Voltage Thresholds at Source

For the purpose of connect detection at the source, the CC1 and CC2 voltage values can be determined by the following example procedure:

  1. Set TCPC_UPC.RDIPSEL to the appropriate power advertising a non-zero value. Set TCPC_UPC.TCIDCTSEL to 6.
  2. Wait for 560 μs or more.

    a. If the TCPC_UPS.CC1ID and TCPC_UPS.CC2RDT comparator outputs are equal to 00b indicating VOPEN voltage value on the CC pins, loop on step 2.

  3. Wait for 450 μs.

    a. If TCPC_UPS.CC1ID and TCPC_UPS.CC2RDT are equal to the previous sampled values, loop on step 3 until tCCDebounce time has elapsed.

    b. If TCPC_UPS.CC1ID and TCPC_UPS.CC2RDT have changed, go back to step 2.

  4. If TCPC_UPS.CC1ID or TCPC_UPS.CC2RDT is 1, the corresponding CCx voltage is VRd, else it is VOPEN.
Note: Only one TCPC_UPC write is required at step 1.

Any other sequence to determine the CC1ID and CC2RDT voltage values is permitted at any time as long as TCPC_UPS.CC1ID and TCPC_UPS.CC2RDT delay update is respected.

If interfacing to a Type-C Port Manager (TCPM), the software has to update the CC Status register (TCPC_CCS) using the Set Status (TCPC_SSR) and Clear Status (TCPC_CSR) registers.