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| 1 | + | # How to DIY a SuzyQ Cable | |
| 2 | + | ||
| 3 | + | ### How a SuzyQ Cable Actually Works | |
| 4 | + | ||
| 5 | + | Chromebooks with a Titan C / Cr50 / Ti50 security chip monitor the USB Type-C Configuration Channel (CC) lines for a specific resistor combination: | |
| 6 | + | ||
| 7 | + | * **CC1 (pin A5):** Pulled to VBUS via a **22 kΩ** resistor. | |
| 8 | + | * **CC2 (pin B5):** Pulled to VBUS via a **56 kΩ** resistor. | |
| 9 | + | ||
| 10 | + | When the Chromebook detects these exact pull-up values upon insertion, it enters Debug Accessory Mode. The internal multiplexer redirects the security chip's USB lines to the USB-C **Sideband Use (SBU)** pins: | |
| 11 | + | ||
| 12 | + | * **SBU1 (pin A8)** becomes **USB D+**. | |
| 13 | + | * **SBU2 (pin B8)** becomes **USB D-**. | |
| 14 | + | ||
| 15 | + | Once connected to your PC, the Chromebook's security chip enumerates natively on your host system as a Google USB composite device (VID:PID `18d1:5014`), exposing serial consoles for the AP and EC, as well as the CCD interface used by `gsctool` and `flashrom`. | |
| 16 | + | ||
| 17 | + | --- | |
| 18 | + | ||
| 19 | + | ### How to Build a DIY SuzyQ (No Microcontroller Required) | |
| 20 | + | ||
| 21 | + | To build one, you only need: | |
| 22 | + | ||
| 23 | + | 1. **A male USB-C breakout board** with access to individual pins (all 24 pins exposed, or at least VBUS, GND, CC1, CC2, SBU1, and SBU2). | |
| 24 | + | 2. **Two resistors:** 1x 22 kΩ (1% tolerance) and 1x 56 kΩ (1% tolerance). | |
| 25 | + | 3. **A sacrificial USB 2.0 cable** (USB-A or USB-C on the PC side). | |
| 26 | + | ||
| 27 | + | #### Wiring Diagram | |
| 28 | + | ||
| 29 | + | | USB-C Male Plug (to Chromebook) | Connection / Resistor | Host USB Cable (to PC) | | |
| 30 | + | | --- | --- | --- | | |
| 31 | + | | **VBUS** (A4, A9, B4, B9 bridged) | Direct wire | **5V (Red)** | | |
| 32 | + | | **GND** (A1, A12, B1, B12 bridged) | Direct wire | **GND (Black)** | | |
| 33 | + | | **CC1** (A5) | **22 kΩ resistor** to VBUS | *(No connection to host)* | | |
| 34 | + | | **CC2** (B5) | **56 kΩ resistor** to VBUS | *(No connection to host)* | | |
| 35 | + | | **SBU1** (A8) | Direct wire | **D+ (White)** | | |
| 36 | + | | **SBU2** (B8) | Direct wire | **D- (Green)** | | |
| 37 | + | ||
| 38 | + | > **Crucial build note:** You **must** use a **male USB-C plug breakout** inserted directly into the Chromebook. Standard USB-C to USB-C or extension cables do not wire both CC lines end-to-end (only one CC wire exists in standard Type-C cables, with the other line used for VCONN). Splicing an existing USB-C cable will fail. | |
| 39 | + | ||
| 40 | + | --- | |
rootiest / How to DIY a SuzyQ Cable
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