STM32 Blue Pill (F103CB) Simulator
The 128 KB Blue Pill, flash size modeled
Simulate the 128 KB Blue Pill (STM32F103CB) in your browser: same Cortex-M3 and pinout as the F103C8 with twice the flash, modeled exactly, running Arduino C++ through the STM32duino core on QEMU.
Three free 15-minute trial sessions · Then Maker and Pro plans · Runs in your browser
STM32 Blue Pill (F103CB) at a glance
The F103CB is the 128 KB Blue Pill: the same Cortex-M3, the same pinout and the same peripherals as the F103C8, with twice the flash. Many boards sold as Blue Pill carry the CB die, which is why both are in the catalog. The flash size is modeled, so a build that fits on one and not the other tells you which board you have.
- Processor
- STM32F103CB, Arm Cortex-M3 at 72 MHz
- Memory
- 20 KB SRAM · 128 KB flash
- Emulation
- QEMU (libqemu-arm) on Velxio's servers
- Languages
- Arduino C++ (STM32duino core)
- Made by
- STMicroelectronics (STM32F103CB)
- Plan
- Trial, then Maker or Pro
What you can do with the STM32 Blue Pill (F103CB) simulator
The board on the canvas is the real thing as far as your code is concerned: the same pins, the same buses, the same peripherals, wired to the same 100+ sensors, displays and actuators every other Velxio board talks to.
Arduino C++ sketches
Write a sketch in the Monaco editor with library completion, compile it against the board's own Arduino core and run the real firmware binary. The Serial Monitor is the USB port.
GPIO, PWM and ADC
Drive LEDs, relays and servos, read buttons and potentiometers, dim with PWM. Every pin follows the board's real pin map, so what works here works on the hardware.
I2C, SPI and UART
Talk to OLEDs, IMUs, ADCs, RTCs and SD cards over the buses the board really has. Bus traffic runs through emulated peripherals, not through a shortcut.
Serial Monitor
USB CDC serial reaches the Serial Monitor at the sketch's baud rate, with input, timestamps and a plotter.
Multi-board canvas
Mix this board with an Arduino, an ESP32 or a Pico on the same canvas and let them talk over serial or I2C, each running its own firmware.
Try it before you subscribe
A free account gets three 15-minute trial sessions on this board family; every run inside a session is free. Unlimited runs are part of the Maker and Pro plans and of Velxio Desktop.
STM32 Blue Pill (F103CB) examples
Ready-to-run projects for this board from the gallery. Open one, read the sketch, press Run.
Related simulators
Frequently asked questions
- How do I know if my Blue Pill is a C8 or a CB?
- Read the marking on the chip: STM32F103C8T6 or STM32F103CBT6. If a sketch overflows on the C8 page and fits here, your board needs the CB die.
- Do Blue Pill examples run on the F103CB?
- Yes, unchanged. The examples on this page are the F103C8's; the CB runs every one of them with flash to spare.
- What does the STM32 simulator cost?
- The editor is free, and any account can place the board and wire a circuit. Running it boots a QEMU guest on Velxio's servers: a free account gets three 15-minute trial sessions on the STM32 family, and unlimited runs are part of the Maker and Pro plans.
- Is the STM32 Blue Pill (F103CB) simulator free?
- Partly. You can build and save a STM32 Blue Pill (F103CB) circuit with any account, and a free account gets three 15-minute trial sessions to run it; every run inside a session is free. Unlimited runs boot a Linux guest on our servers, so they are part of the Maker and Pro plans, or of Velxio Desktop with a paid licence.
- Which languages can I use on the STM32 Blue Pill (F103CB)?
- Arduino C++ (STM32duino core). The language is switched from the toolbar; the circuit on the canvas stays the same.
Ready to simulate the STM32 Blue Pill (F103CB)?
Open the editor, place the STM32 Blue Pill (F103CB) from the picker, wire what you need and press Run.
Launch the STM32 Blue Pill (F103CB) simulator →