: The PC has recognized the device in "Download Mode" using the SCI-USB2Serial v1.5.6.1 (or similar) driver.
| Symptom | Cause | Fix | |---------|-------|-----| | Device shows as "Unknown" | Vendor-class interface | Force-load cdc_acm with vendor_class=1 or patch INF | | Only one channel visible | Driver only binds first bulk endpoint | Use Spreadtrum official driver | | Garbage data on /dev/ttyUSB0 | Raw payload without framing | Use sci_decoder tool to strip headers | | Intermittent disconnection | Power saving: USB autosuspend | echo on > /sys/bus/usb/devices/.../power/control | spreadtrum sci usb2serial ok
| Tool | Purpose | Port used | |------|---------|------------| | (Spreadtrum official) | Flash firmware (PAC format) | Diag (auto) | | Coolpad Download Assistant | Flash / backup | Diag | | HyperTerminal / PuTTY / minicom | AT commands, manual log capture | Diag port | | ModemMaster / QXDM (adapted) | NV editing, signal debugging | Diag | | screen / cat (Linux) | Raw log dump | Debug port | : The PC has recognized the device in
struct sci_frame *frame = urb->transfer_buffer; u8 channel = frame->channel; u16 len = frame->length; // Demux to appropriate tty device if (channel == 0) tty_insert_flip_string(&sci_tty[0], frame->payload, len); else if (channel == 1) tty_insert_flip_string(&sci_tty[1], frame->payload, len); // ... It functions as a bridge that allows a
The is a specialized communication interface produced by Spreadtrum . It functions as a bridge that allows a Windows PC to treat a connected smartphone or tablet as a standard COM (serial) port. This connection is critical for performing advanced maintenance tasks such as: