Because the official firmware support was inconsistent, the community took matters into their own hands. The most interesting development in the TC2 firmware scene is the "Porting" phenomenon.
Talented developers (often appearing on GitHub and the EEVblog forums) decided that the stock UI was terrible and started writing their own. The most famous of these is likely the DSO138 ports and other custom UIs adapted specifically for the TC2’s screen resolution and button layout.
These custom firmwares offered features the manufacturer didn't bother with:
Installing these was a high-stakes gamble. It required opening the case, finding the hidden programming pads (often unpopulated holes on the PCB), and using an ST-Link programmer to overwrite the chip. It was "interesting" because it turned a consumer device into a DIY kit after you bought it.
[1] FNIRSI. (2022). DSO-TC2 User Manual.
[2] STMicroelectronics. (2019). STM32F405/415 Reference Manual.
[3] Winbond. (2018). W25Q16JV Datasheet.
[4] Reverse Engineering STM32 Firmware, Embedded Lab, 2021.
[5] “FNIRSI DSO-TC2 Teardown,” EEVblog Forum, 2023.
Note: This paper is a template. Actual addresses, offsets, and exact MCU variant depend on your specific DSO-TC2 hardware revision. Always verify before attempting reflashing.
Updating the firmware on the FNIRSI DSO-TC2 —a 2-in-1 handheld digital oscilloscope and transistor tester
—allows users to improve measurement accuracy and access newer features. Official firmware updates are provided by FNIRSI to address known issues and enhance the device's online operation capabilities with a computer. Firmware Update Overview
supports online firmware refreshing, which is typically done through a direct connection to a Windows-based PC Official Downloads
: Firmware files and relevant PC software can be found on the FNIRSI Software Downloads page Manuals & Firmware repository Version History
: Users often look for updates to transition from older versions (like v1.6) to newer iterations for improved stability, though it is generally recommended to only update if you encounter specific faults. How to Update the Firmware
The update process generally involves the following steps based on official FNIRSI procedures: Preparation : Download the correct firmware package for the official FNIRSI website
. Ensure you have a Micro USB or Type-C data transfer cable (depending on your specific hardware revision). Connection
: Connect the device to your computer. Open the FNIRSI PC software and select the appropriate communication port found in your computer's Device Manager Enter Update Mode in the software. Once successful, navigate to the "Firmware Upgrade" section and select "BOOT/Restart" to put the device into upgrade mode. Transferring Files fnirsi dso-tc2 firmware
: The device may appear as a USB flash drive on your computer. Copy the new firmware file into this drive. The device will then automatically begin the upgrade process. Completion
: Monitor the progress percentage on the device or software. The will automatically restart once the update is complete Key Considerations Hardware Variants : Be cautious to download the firmware specifically for the . Using firmware intended for related models like the can brick the device. Common Issues
: If the upgrade fails or the device becomes unresponsive, users sometimes need to disconnect and reconnect the internal battery while holding specific buttons to force it back into upgrade mode. Alternative Firmware
: There has been community discussion regarding porting Atmel-based transistor tester firmware to the Cortex M processor used in the TC2 to potentially increase performance, though this is considered unofficial. or a link to a video walkthrough for this process?
To update or troubleshoot the firmware on your FNIRSI DSO-TC2, you can follow the official procedures for accessing the update mode and applying the software. Firmware Update Instructions
For the DSO-TC2, the process involves mounting the device as a USB drive on your computer:
Connect to PC: While the instrument is off, connect it to your computer using a Type-C data cable that supports data transfer.
Enter Boot Mode: Turn the device on. Wait approximately 2 seconds after booting for the computer to recognize it.
Verify Connection: Check if a removable disk named "CH BOOT" appears on your computer.
Transfer Firmware: Copy the firmware file (typically starting with "CH") directly into the root folder of the "CH BOOT" drive.
Completion: Once the copy is finished, the screen should display an "Update completed" message. Where to Get the Firmware
You can find official firmware files and user manuals on the FNIRSI Manuals & Firmware Downloads page. If the file is not listed under the specific TC2 model, check the FNIRSI Official Firmware Upgrade section for general updates. Troubleshooting Tips
Blank Screen: If you encounter a blank screen during the update, some users have found success by formatting the internal drive before dragging the firmware file into it. Because the official firmware support was inconsistent, the
Cable Issues: Ensure you are using a high-quality data cable; some "charging-only" cables will not allow the "CH BOOT" drive to appear.
Version Verification: You can verify your current firmware by checking the "About" or "System Info" section in the device settings.
If you're having trouble finding the specific file or if the device won't boot, let me know so I can help you find a mirror link or alternative fix.
The FNIRSI DSO-TC2 uses a dual-firmware architecture because the device is powered by two separate microcontrollers (MCUs). One MCU handles the oscilloscope functions, while the other manages the transistor tester and component analysis. 🛠️ Dual-Firmware Structure
Because there are two processors, updates are split into two distinct file types. You must update them individually to fully refresh the device. DSO Firmware (Oscilloscope) Prefix: Files starting with CHD.
Function: Controls the 200kHz bandwidth scope, trigger modes (Auto/Normal/Single), and waveform display. TC2 Firmware (Transistor Tester) Prefix: Files starting with CHT (or sometimes MM).
Function: Manages component identification, hFE measurements, and LCR meter functions. 🔄 How to Update
The DSO-TC2 updates via USB Drag-and-Drop. The device mimics a USB drive when put into the correct mode. 1. Update the Oscilloscope (CH)
Enter Mode: Connect the device to a PC via Type-C while it is OFF. Boot: Turn the device on and wait ~2 seconds.
Disk Name: Look for a drive named "CH BOOT" on your computer. Action: Copy the CHD firmware file into this drive.
Confirmation: The screen will display "Update completed" at the bottom. 2. Update the Transistor Tester (MM) Enter Mode: Connect to PC while the device is OFF. Boot: Press and HOLD the Down Arrow key, then turn it on. Disk Name: Look for a drive named "MM BOOT". Action: Copy the CHT or MM firmware file into the drive.
Confirmation: The unit will automatically restart once the transfer is finished. ⚠️ Key Considerations
Cable Quality: Use a USB-C cable that supports data transfer (D+ and D- pins), not just charging. Installing these was a high-stakes gamble
Single File Limit: You can only flash one file at a time. If you have both updates, complete one, disconnect, and repeat the process for the second.
Official Sources: Download legitimate files directly from the FNIRSI Software Download Page or their official Firmware Upgrade Portal.
Bricking Risk: Always ensure the battery is charged before starting. Some users report units failing to boot if the process is interrupted. Oscilloscope Transistor Tester
Despite being built on open-source code, the DSO-TC2’s firmware is not open source. Fnirsi does not release the source code or the toolchain. This has frustrated the hacker community, who would otherwise fix bugs, add features (like better triggering or serial decoding), or port the firmware to other devices.
As a result, a small but dedicated group of reverse engineers has attempted to dump and analyze the firmware. They discovered that:
This closed-source approach is a commercial decision: Fnirsi wants to prevent clones and protect their “secret sauce,” even though the sauce is borrowed. The result is a device that cannot be fully customized or repaired through software—a loss for the maker community that the device ostensibly serves.
Currently, the most intriguing project in the TC2 firmware world is the attempt to unify the split personality of the device.
Since the stock device has to restart to switch between Scope mode and Tester mode, developers have been trying to write a unified RTOS (Real-Time Operating System) firmware. Imagine a firmware where you can press a button and instantly switch from looking at a PWM signal to testing a diode, without the 3-second boot-up delay.
While still in experimental stages for many GitHub forks, this represents the "Holy Grail" for TC2 owners. It highlights the reality of this device: The hardware is capable of much more than the official software allows.
The most compelling chapter in the TC2 firmware saga involves the relationship between the manufacturer and the community.
For a long time, FNIRSI was notoriously secretive about their source code. While they eventually released some code, the community quickly realized that the provided source didn't match the optimized binaries running on the devices. This led to a wave of skepticism.
However, the real drama started when people tried to modify the firmware. Unlike more hacker-friendly brands, FNIRSI devices were often protected. There were reports of "anti-tamper" mechanisms where, if the firmware detected unauthorized modification or if the user attempted to downgrade, the device would lock up or "brick" itself. This turned a $50 tool into a paperweight, sparking outrage on forums like EEVblog and Reddit. It created a "cat-and-mouse" game: FNIRSI would patch security holes, and hackers would find new exploits to unlock the bootloader.
The SPI flash is not protected either. Using a Bus Pirate or dedicated programmer:
Contents: Framebuffer tiles, calibration tables, and strings.
The DSO-TC2 is a 2-in-1 oscilloscope (200 kHz bandwidth) + transistor tester. Its firmware is closed-source and updated via a .upd file using a Windows PC tool (no OTA or macOS/Linux native support).