EDL Forced Download Mode

The Rhino Pi IQ9N (Rhino Pi IQ9N) is based on the Qualcomm IQ9075 platform. When the system fails to boot normally, you can enter EDL (Emergency Download) mode to perform forced flashing.

Two boot mode select signals are brought out on the board: FORCE_BOOT_M and FORCE_BOOT_S, corresponding to the CPU BOOT button and the RTSS BOOT button respectively. Entering EDL mode uses the RTSS BOOT button (FORCE_BOOT_S).

Related Interfaces

For the positions of the RTSS BOOT button and the debug/functional UARTs on the board, see the interface layout diagram in Rhino Pi IQ9N Interface Description on the first page.

Interface/Button	Description
RTSS BOOT button	Corresponds to signal FORCE_BOOT_S; press and hold it, then power on to enter EDL (forced download) mode
CPU BOOT button	Corresponds to signal FORCE_BOOT_M; CPU subsystem boot mode selection
CPU-DBG	CPU debug UART, WAFER-GH1.25-4PLB, 3.3V level
CPU-UART	CPU functional UART, WAFER-GH1.25-4PLB, 3.3V level
RTSS-DBG	RTSS debug UART, WAFER-GH1.25-4PLB, 3.3V level
RTSS-UART	RTSS functional UART, WAFER-GH1.25-4PLB, 3.3V level

UART Interface Definitions

The debug and functional UARTs all use WAFER-GH1.25-4PLB connectors:

Pin	Signal	Description
1	VCC_3VS	3.3V power
2	UART_TX	UART transmit
3	UART_RX	UART receive
4	GND	Ground

Use Cases

The device can be recovered through EDL mode in the following situations:

• The system image is corrupted and the device cannot boot normally
• The complete firmware needs to be re-flashed
• A failed upgrade has bricked the device

Procedure

For the complete entry method and flashing process, see Ubuntu System Installation. The brief steps are as follows:

1. Use a USB TYPE-A to TYPE-C data cable to connect the computer to the device, and run adb devices to confirm the device is recognized.

2. Run adb root; adb shell reboot edl to enter EDL mode; if the system cannot boot, disconnect the device power, press and hold the RTSS BOOT button, then press the power button to power on; the device enters EDL mode and the button can then be released.

   

3. In QFIL, configure Configuration; in the port list select Qualcomm HS-USB QDLoader 9008 (COMx), set Select Build Type to Flat Build, and load prog_firehose_ddr.elf and the XML files from the ROM package.

4. Click Download to start flashing, and wait for the Download Succeed message; the device then reboots automatically.

Note

For the complete flashing order and every QFIL setting, refer to Ubuntu System Installation. This page only describes how to enter EDL mode.

Notes

• Entering EDL mode requires a USB connection and dedicated flashing tools; use the tools and firmware packages provided by the manufacturer.
• Do not power off or unplug cables during flashing, as this may leave the device unrecoverable.
• The UART interfaces are at 3.3V level; do not connect 5V serial devices directly, to avoid damaging the chip.