| Issue | Workaround | |-------|-------------| | SPI clock glitches after reset | Add 10 ms delay after CMD_RESET before any SPI access | | Interrupt line stuck high | Implement IRQ re-trigger detection; reset chip if no finger seen after 5 s | | Image rows out of order | Some firmware versions require row address re‑sent per row – use single‑row reads |

From reverse‑engineered traces, the CS9711 uses a 3‑wire SPI variant (SDIO shared) with:

Command: [OPCODE (1 byte)] [ADDR (2 big‑endian)] [LEN (1 byte)] [CRC8]
Response: [STATUS (1 byte)] [DATA (LEN bytes)] [CRC16]

Common opcodes:

Score: 4.5/5 The strongest selling point of the CS9711 driver is its seamless integration with Windows Hello.