Recovering the Firmware

This section explains how to resolve firmware-related issues.

Recovering the firmware may be necessary if a firmware update fails or incompatible firmware is loaded. Attempt flashing the bootloader via the SWD port if the Here4 LEDs are solid white.

Prerequisites

The following information is for J-Link devices, but it can also be applied to similar devices when using an ST-Link.

• J-Link device:

  • EDU Mini V2, for personal/educational use (and an adapter board)

  • BASE Compact, for commercial use

    • Pinout: https://www.segger.com/products/debug-probes/j-link/technology/interface-description/

• 6-pin JST SUR plug for SWD port

  • Refer here for SWD port pinout: FMU Debug pinout

• Download and install “J-Link Software and Documentation Pack” from segger.com/downloads/jlink/

• Download the bootloader file for your flashing tool:

  • JLink: Here4_bl.hex

  • STLink: Here4_bl.bin

• De-cased Here4

  • Remove M3 bolt (2 mm hex head)

  • Gently separate the two housing parts, using a plastic tool to pry the clips apart

  • Images for reference:

Procedures

J-Link with J-Flash Lite

1. Plug Here4 into CAN port of a Cube (for power).

2. Plug J-Link into the SWD port on the Here4.

1. Connect J-Link to PC over USB.

2. Open J-Flash Lite (JFlashLite.exe).

3. Use the following parameters:

1. Click OK.

2. Plug the Cube into power, power up the Here4, and click Erase Chip.

1. Click the button under Data File and open the Here4_bl.hex file.

2. Click Program Device.

3. Check the log for the following output:

1. Unplug the power and SWD connections.

2. Plug in Cube, connect to Mission Planner and verify Here4 shows up in DroneCAN (in MAINTENANCE mode).

3. Update the Here4 (Menu -> Update -> Yes, search the internet for updates).

4. Verify Here4 shows up in OPERATIONAL mode.

Connect Programming Devices

This section contains the pinout on either side to assist in connecting the J-Link or ST-Link device to the SWD port. The same pinout is used for J-Link and ST-Link devices with 20-pin connectors.

Solder or crimp the 6-pin JST SUR wires onto 2.54 mm female header plugs (if using programming devices with header pins).

Pin Number (SWD port)	Name (SWD port)	Pin Number (JTAG Interface)	Name (JTAG Interface)
1	VDD 5V PEIPH	1	VTref
2	FMU_TX (SERIAL 5)	Not Connected	Not Connected
3	FMU_RX (SERIAL 5)	Not Connected	Not Connected
4	FMU-SWDIO	7	SWDIO
5	FMU-SWCLK	9	SWCLK
6	GND	4	GND

• SWD port pinout

• J-Link pinout ('SWD Connector Pinout' section)

• ST-Link pinout