J-Link OB-RA4M2_V1.1, All-in-One OB

Function Description:
1. Supports most core architecture chips on the market;
2. Supports SWD and JTAG;
3. Supports VCOM serial port function;
4. Includes 1-channel signal status indicator.
Hardware: 1.

PCB 3D Preview:

2. PCB Physical Image
3. Finished Product Image
Software:
1. Firmware Download
Firmware loading is somewhat special and requires certain modifications to download. This OB is powerful (supports a wide range of cores), which is its advantage, but also its "disadvantage"; as the saying goes, "a doctor cannot heal himself," often the more powerful it is, the more difficult it is to maintain when problems arise. You will find that previous JLink or OB debuggers could not download firmware to it because its main controller is R7FA4M2AB3CFL, an Arm® Cortex®-M33 Core, Armv8-M architecture MCU. If your JLink or OB debugger does not support the Armv8-M architecture, then you will not be able to download firmware, unless you have a Renesas dedicated downloader, which is a different story.
To solve this tricky problem, I collaborated with user O2C14. He provided the modified files, and I conducted hardware compatibility tests, finally resolving the issue. According to his description, the original JLink or OB supports downloading Armv8-M architecture chips, but the JFlash software imposed restrictions. The solution was to modify the software, specifically modifying the relevant files to enable this architecture. I didn't delve into the exact implementation, but he provided a modified file, which I used to replace the existing one. The general method involves modifying the JLink_x64.dll file to support Armv8-M architecture chip downloads. The attached JLink_x64.dll file is modified from JFlash-V7.94e. Therefore, if you want to download firmware using a debugger that doesn't support this architecture, you can install JFlash-V7.94e and replace the original dll file to support firmware downloads. (Special Note: The DLL only modifies relevant restrictions and does not make other modifications. It does not contain plugins or other elements, so you can download it with confidence. However, we do not guarantee that replacing this file will not cause software crashes or other unknown problems. Neither I nor the original author assume any risk of unknown problems arising from replacing this file. By using it, you agree to the above statement and are willing to bear the risks involved. Therefore, please back up the original file for future use. Thank you.) The original version does not support the following:
After replacing the DLL file, the firmware download is successful:
2. SN Modification:
Based on my personal testing, the original firmware (excluding SN and Licenses) only supports one command to modify the firmware, i.e., either modify the SN once or add a License; however, this does not meet our needs. Through comparative research, we found that the SN address is located at firmware address 0x6000, while the License starting address is located at 0x6020, as shown in the figure below:
The SN encoding rule is the hexadecimal number corresponding to the decimal SN, taking the first 2 to 3 digits as the prefix. As shown in the image above, the SN is 23121301, corresponding to the hexadecimal number 160CD95. Each byte is stored in a group in the address, using little-endian mode, taking the first two digits 23 as the prefix. Therefore, the data represented in the address is: 95 CD 60 01 (the high-order byte is stored at the high address). (PS: This is my personal understanding; please forgive any inaccuracies or omissions). Understanding the SN encoding rules gives us a clue as to how to modify the SN and where to start.
Why modify the SN? Of course, it's to differentiate between different links or for personalization, since everyone may want to set a different SN. Then some people ask, why specifically mention SN modification? Can't it be modified via command (although only once)? The answer is that the original firmware only supports one command modification (a solution hasn't been found yet). Either modify the SN or add a License, but obviously neither of these can meet our needs. Even if you manually add Licenses first, once the original firmware has been modified, you cannot modify the firmware content again via command. While licenses are fixed, only the serial number (SN) varies from person to person.
Therefore, firmware for adding license information and the SN encoding rules are provided for DIY customization. To modify the SN, simply use the firmware provided in the attachment, convert it using a calculator according to the encoding rules, modify the SN content in the firmware, and finally download it to the debugger. Of course, if a better method is developed later, I will update it; if any friends discover one, I hope they can share it to benefit everyone.
3. VCOM Enabling
The original firmware has VCOM disabled by default. It can be enabled using the `VCOM enable` command or disabled using the `VCOM disable` command. This command can be executed repeatedly without limit, but the command only takes effect after the debugger is powered on again.
VCOM enable:
VCOM disable:
VCOM is enabled at address 0x8089 in the firmware. Below is a comparison of firmware information with VCOM disabled and enabled:
The firmware in the attachment has been modified to have VCOM enabled by default.
Special Note:

Virtual serial port CDC
enable is switched by shorting the header pins with an external jumper. By default, it uses the JTAG signal TDI and TDO paths when not connected; shorting SEL and TRST with the jumper switches to the serial port signal TXD and RXD paths.

2. Firmware Download Special Note:
You need to use a 5-pin header to connect VCC, GND, JTMS, JTCK, and JRST to other OB debuggers simultaneously; otherwise, connection failures may occur.
Follow-up:
Follow-up 1: Upgradeable Firmware_24-09-23 Update


Preface
A couple of days ago, by chance, I saw an upgradeable OB-RARM2-Full firmware shared online by a guru, zhangjinke. The original address is: J-Link-OB-RA4M2. Those interested can go and check it out. So, out of curiosity, I downloaded it to take a look. After some testing, it is indeed upgradeable (with a built-in bootloader). So, let's update it.


Firmware Testing
The firmware download is no different from before. It requires a downloader that supports the Cortex-M (ARMv8-M) core. You can use the previously modified files to replace them. However, another method has now emerged. Zhangjinke's GitHub page provides another firmware, "J-Link OB-STM32F072-128KB-CortexM," which, while not supporting automatic updates, does support Cortex-M (ARMv8-M) core architecture chips. Testing shows that downloading and supporting the RA4M2 processor is feasible, except for an update error when using a new driver. The following precautions should be taken when downloading:
a) Firmware feasibility test. After the firmware download is complete, connect the debugger to the computer and open J-Link Commander. If a new firmware version (higher than J-Link OB-RA4M2-Full compiled Sep 13 2023 14:47:56) is available, it will indicate that the debugger is currently in bootloader mode. Confirm the update and enter bootloader mode; otherwise, enter bootloader mode directly, as shown below:


New firmware prompts bootloader mode; confirm the update and enter bootloader mode:
As you can see, the initial SN = -1, and a license has been added. Based on past experience, the old version of J-Link Commander could be used to add the SN via command, but this doesn't work. Therefore, the old method of manually adding the SN is necessary. The SN is stored in the chip's memory address in little-endian alignment, i.e., in hexadecimal format. Two numbers form one byte of data, stored in little-endian alignment. For example, the SN is 24060501, corresponding to the hexadecimal format 16F2255. According to the SN encoding rules, its storage method in memory is: 55 22 F6 01 (the low byte is stored at the low memory address, and the high byte at the high memory address), as shown below.
Next, let's test if the VCOM function is working properly. VCOM is enabled by default. If it is not enabled, you can use the command: VCOM enable in J-Link Commander. The VCOM test results are as follows:
Finally, let's test if the debugger's SWD download function is working properly. The test results are as follows:
That's all for this update. No further testing was done; interested readers can test it themselves. By the way, a bug has been discovered: occasionally after reconnecting, it prompts that the debugger is in bootloader mode, which can be entered after confirmation; a solution has not yet been found, and the specific cause and impact require further research and testing. Regarding the firmware, I will attach one or two firmware files with the serial number added. For the original firmware and other related materials, you can download them from the original author.
Update 2: Adding RDI_24-09-26.
The original firmware did not include the RDI-License, so it was manually added. The attachment contains a re-uploaded version with RDI information, as shown below:
[Disclaimer] To avoid copyright disputes, this OB debugger is for DIY enthusiasts or personal use only. Its creation and use must comply with relevant open-source licenses and may not be used for commercial purposes. Any violation will be the sole responsibility of the user. The final interpretation rights of the OB circuit and related source code firmware belong to Segger. I do not provide any form of technical support or service, nor do I assume any responsibility for any consequences arising from improper use. Please be aware of this disclaimer.