Scope Out These Functioning Mini Oscilloscopes
These small, STM32-powered tools may lack all the capabilities of a traditional oscilloscope, but still provide basic readings.
Inspired by various DIY oscilloscopes online, hobbyist Wilko Lunenburg took it upon himself to see just how small they could make the device. While his mini oscilloscope doesn’t have all the capabilities of a real oscilloscope, it still provides basic electrical readings. Most DIY 'scopes are made with an Arduino, but this one utilizes the smaller STM32F030F4 microcontroller for more speed. It’s equipped with the typical timers, like SPI, RTC, a USART, and two watchdogs. It also uses the STLink-V2 for programming.
Aside from the Cortex-M0 MCU, most of the parts Lunenburg used to build the unit include:
- Plastic box (12 x 8 x 3 cm)
- Perfboard (double-sided prototype board 8x12cm)
- TSSOP20 to DIP board
- ST7735s 1.8" TFT display
- Lithium-ion battery
- Lithium-ion charger board
- HT7333 3.3V low dropout regulator
- MCP6021 op amp
- 8MHz crystal
- Rotary encoder plus knob
- Power switch
- Banana terminals
- Several resistors and capacitors, nylon spaces, nuts and screws
The specs are as follows:
- Input resistance
- 1Mohm sensitivity
- 1V/div timebase 200ms/div...40us/div
- -6V to 6V input voltage
- Trigger level on-screen
- Battery-powered
What's more, Lunenburg designed a mini dual-trace oscilloscope using a Blue Pill with two ADCs in the “interleave” mode for double the speed. This updated version also has more features than its predecessor, including two channels, variable sensitivity on both channels, variable trigger level on both channels, variable offset, and single battery power.
You can see the step-by-step process and find the code for both oscilloscopes here and here.