Fnirsi Dso-tc2 Firmware Here

The Tale of the TC2: Bricked Scopes and Reverse Engineering

Or: Why the FNIRSI TC2 Firmware Scene is the "Wild West" of Electronics

In the crowded market of cheap handheld oscilloscopes, the FNIRSI DSO-TC2 occupies a strange and fascinating niche. On the surface, it looks like a miracle of integration: a 2-in-1 device combining a digital oscilloscope and a transistor tester (similar to the famous TC1/T7 testers), all for a remarkably low price.

But beneath the plastic casing and the glowing screen lies a firmware story that reads like a drama series, filled with villainous bricking attempts, community revolt, and the triumph of open-source reverse engineering. fnirsi dso-tc2 firmware

What Works Well

• Out-of-box stability – Recent firmware versions (v1.3.x and later) fixed early showstoppers like screen glitches and inaccurate capacitance readings.
• Transistor tester – Uses an adapted avr-transistortester algorithm; firmware correctly identifies pinout, hFE, diode Vf, and MOSFET gate threshold.
• Auto-setup on scope – The horizontal/vertical scaling works reliably after the v1.3.3 update.

6.1 Positive: Community Repair

Enthusiasts can fix bugs, add features (e.g., UART logging, trigger holdoff), or repurpose the device.

3.3 Reading External SPI Flash

The SPI flash is not protected either. Using a Bus Pirate or dedicated programmer: The Tale of the TC2: Bricked Scopes and

• Desolder or clip onto pins 1-8 (CS, DO, DI, CLK, etc.)
• Dump with flashrom -p buspirate_spi -r external.bin

Contents: Framebuffer tiles, calibration tables, and strings.

2. The Oscilloscope Side: A Minimalist Implementation

Where the component tester excels, the oscilloscope firmware reveals the device’s cost-cutting nature. The DSO-TC2 is marketed as a 2.5 MHz analog bandwidth scope with a 10 MSa/s sampling rate—adequate for audio frequencies and basic microcontroller debugging (e.g., checking PWM signals or I2C clock lines). The firmware manages the STM32’s ADC (analog-to-digital converter) and DMA (direct memory access) to capture waveforms, then renders them on the display. Out-of-box stability – Recent firmware versions (v1

However, the firmware’s limitations become apparent upon deeper use:

• Triggering is rudimentary: Only edge triggering is available, with no support for pulse, video, or slope triggering. The firmware’s trigger logic is software-based, leading to noticeable latency and jitter.
• Measurement cursors are basic: While horizontal and vertical cursors exist, automatic measurements (Vpp, frequency, duty cycle) are slow to update and often inaccurate at higher frequencies.
• No persistence or math functions: Features like waveform persistence, FFT, or channel math are absent. The firmware shows only the live trace or a frozen capture.

These are not hardware limitations alone; they are deliberate firmware simplifications. The STM32F103 (or similar) inside the DSO-TC2 has enough power to implement basic digital triggering and averaging, but Fnirsi chose not to invest in the firmware development. Instead, the oscilloscope mode feels like a proof-of-concept—enough to claim “oscilloscope” on the box, but not enough for serious debugging.

Problem 3: Update Completes, but Touch/Buttons Don't Work

• Solution: A configuration mismatch. Perform a factory reset (Menu -> System -> Factory Reset). If that fails, reinstall the firmware but this time, also copy a config.txt or calib.ini file if one was included in the original download.