The PC and STB are not talking at the same speed. If the STB’s BootROM listens at 115200 baud, but your terminal sends at 921600, the bits are garbled. The STB’s UART tries to assemble corrupted bytes, cannot find a valid frame, and the buffer fills with noise.
: Set your adapter to 3.3V (most common for STBs) unless the board specifically requires 5V. Adjust Software Tool Settings The PC and STB are not talking at the same speed
Automated and guided actions:
| Check | Action | |-------|--------| | | Ensure host matches BootROM default (often 115200 or 921600). Mismatch = garbage data. | | Flow control | Disable hardware flow control (RTS/CTS) at BootROM stage – it's usually not supported. | | RX line noise | Disconnect/reconnect GND. Use shielded cable if in noisy environment. | | Host software | Stop any terminal auto-send (e.g., line feeds, CR, timestamps) before device powers on. | | Boot sequence | Power device first, then connect UART RX – or vice versa depending on SoC (check datasheet). | : Set your adapter to 3
: The device has entered its low-level boot mode and is waiting for the PC software to send the initial command (0x7F or similar) to start the transfer. | | Flow control | Disable hardware flow
