KV4P
1. USB-C includes the OTG (On-The-Go) spec, which lets devices switch between host and client mode. 2. To negotiate roles, the client device (like an ESP32 board) should signal its role using two 5.1k–5.4k pull-down resistors on the CC lines. 3. If those resistors are present, you can use a standard USB-C cable and things just work. 4. Some cheap ESP32 boards from China skip those resistors, which breaks the detection logic. 5. To work around that, some vendors bundle “special” OTG cables or adapters that include the resistors inside the cable. 6. OTG cables/adapters are directional — the end with the resistors must go into the client device. Sometimes this is marked, but not always. 7. Some adapters or cables only have one resistor instead of two, which breaks USB-C's flippable/unipolar connector design — it may only work when plugged in a certain way.
