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STM32 Nucleo-F411RE
2014 Open source · CC0 On-board only Online
The STM32 Nucleo-F411RE is STMicroelectronics' popular low-cost developer board — an STM32F411RE (a 100 MHz ARM Cortex-M4F, ARMv7E-M with a single-precision FPU, with 512 KB flash and 128 KB SRAM) with an on-board ST-Link debugger — emulated from scratch in the browser on this site's shared ARM core. It runs REAL compiled firmware: a flat flash image with the ARM vector table at 0x08000000 boots exactly as on silicon (SP and PC loaded from the table), then drives the real STM32F411 registers. The on-board surface a Nucleo actually has is shown — the green user LED LD2 on PA5 (active-high), the blue user button B1 on PC13 (active-low) and a USART2 serial console (the ST-Link virtual COM port) — with nothing invented: no breadboard, no fake audio (a Nucleo has no speaker, so it is honestly silent). Because the whole chip is ordinary JavaScript, it plugs into this site's shared debugger: the real Thumb-2 disassembler, live r0-r15 / xPSR / N-Z-C-V and the FPU s0-s31, side-effect-free FLASH / SRAM / peripheral memory at the real addresses, single-instruction step, execution breakpoints and write-watchpoints.
NUCLEO-F411RE at STMicroelectronics ↗
Runs on: Web browser
STM32 Nucleo-F411RE Online Emulator
Play STM32 Nucleo-F411RE using JavaScript directly in your browser.
Controls
Runs real compiled STM32F411RE firmware on an in-browser STMicroelectronics STM32F411 (ARM Cortex-M4F, 100 MHz, with FPU) as fitted to the ST NUCLEO-F411RE board. The default is "Blink LD2": a bare-metal C program that enables the GPIOA clock in RCC, configures PA5 as an output and blinks the green user LED (LD2 on PA5 is active-high, so the LED lights when the pin is driven high). "Button toggles LD2" makes the blue user button B1 (on PC13, active-low with a pull-up) toggle the LED on each press — press B1 in the Controller panel. "USART2 Serial" brings up USART2 (TX on PA2 — the ST-Link virtual COM port) and prints a greeting then an incrementing counter to the serial console while blinking LD2. "Timer Blink (TIM2)" blinks the same LED but times it off the TIM2 general-purpose timer. All four are original CC0 programs compiled with clang for thumbv7em. Open the debugger, or add ?debug, to single-STEP real Thumb instructions from flash at 0x08000000, set PC breakpoints and write watchpoints (e.g. watch USART2->DR at 0x40004404), and read the ARM registers (r0-r15, xPSR, N/Z/C/V and the FPU s0-s31) and the real STM32F411 memory map live (FLASH 0x08000000, SRAM 0x20000000, peripherals 0x40000000). A Nucleo has no on-board speaker, so it is honestly silent.
Runs real compiled STM32F411RE firmware on an in-browser STMicroelectronics STM32F411 (ARM Cortex-M4F, 100 MHz, with FPU) as fitted to the ST NUCLEO-F411RE board. The default is "Blink LD2": a bare-metal C program that enables the GPIOA clock in RCC, configures PA5 as an output and blinks the green user LED (LD2 on PA5 is active-high, so the LED lights when the pin is driven high). "Button toggles LD2" makes the blue user button B1 (on PC13, active-low with a pull-up) toggle the LED on each press — press B1 in the Controller panel. "USART2 Serial" brings up USART2 (TX on PA2 — the ST-Link virtual COM port) and prints a greeting then an incrementing counter to the serial console while blinking LD2. "Timer Blink (TIM2)" blinks the same LED but times it off the TIM2 general-purpose timer. All four are original CC0 programs compiled with clang for thumbv7em. Open the debugger, or add ?debug, to single-STEP real Thumb instructions from flash at 0x08000000, set PC breakpoints and write watchpoints (e.g. watch USART2->DR at 0x40004404), and read the ARM registers (r0-r15, xPSR, N/Z/C/V and the FPU s0-s31) and the real STM32F411 memory map live (FLASH 0x08000000, SRAM 0x20000000, peripherals 0x40000000). A Nucleo has no on-board speaker, so it is honestly silent.
Runs real compiled STM32F411RE firmware on an in-browser STMicroelectronics STM32F411 (ARM Cortex-M4F, 100 MHz, with FPU) as fitted to the ST NUCLEO-F411RE board. The default is "Blink LD2": a bare-metal C program that enables the GPIOA clock in RCC, configures PA5 as an output and blinks the green user LED (LD2 on PA5 is active-high, so the LED lights when the pin is driven high). "Button toggles LD2" makes the blue user button B1 (on PC13, active-low with a pull-up) toggle the LED on each press — press B1 in the Controller panel. "USART2 Serial" brings up USART2 (TX on PA2 — the ST-Link virtual COM port) and prints a greeting then an incrementing counter to the serial console while blinking LD2. "Timer Blink (TIM2)" blinks the same LED but times it off the TIM2 general-purpose timer. All four are original CC0 programs compiled with clang for thumbv7em. Open the debugger, or add ?debug, to single-STEP real Thumb instructions from flash at 0x08000000, set PC breakpoints and write watchpoints (e.g. watch USART2->DR at 0x40004404), and read the ARM registers (r0-r15, xPSR, N/Z/C/V and the FPU s0-s31) and the real STM32F411 memory map live (FLASH 0x08000000, SRAM 0x20000000, peripherals 0x40000000). A Nucleo has no on-board speaker, so it is honestly silent.
Runs real compiled STM32F411RE firmware on an in-browser STMicroelectronics STM32F411 (ARM Cortex-M4F, 100 MHz, with FPU) as fitted to the ST NUCLEO-F411RE board. The default is "Blink LD2": a bare-metal C program that enables the GPIOA clock in RCC, configures PA5 as an output and blinks the green user LED (LD2 on PA5 is active-high, so the LED lights when the pin is driven high). "Button toggles LD2" makes the blue user button B1 (on PC13, active-low with a pull-up) toggle the LED on each press — press B1 in the Controller panel. "USART2 Serial" brings up USART2 (TX on PA2 — the ST-Link virtual COM port) and prints a greeting then an incrementing counter to the serial console while blinking LD2. "Timer Blink (TIM2)" blinks the same LED but times it off the TIM2 general-purpose timer. All four are original CC0 programs compiled with clang for thumbv7em. Open the debugger, or add ?debug, to single-STEP real Thumb instructions from flash at 0x08000000, set PC breakpoints and write watchpoints (e.g. watch USART2->DR at 0x40004404), and read the ARM registers (r0-r15, xPSR, N/Z/C/V and the FPU s0-s31) and the real STM32F411 memory map live (FLASH 0x08000000, SRAM 0x20000000, peripherals 0x40000000). A Nucleo has no on-board speaker, so it is honestly silent.
Configurations
| Configuration | Emulator | Machine | OS | Legal | |
|---|---|---|---|---|---|
| Blink LD2 (on-board LED) | STM32 Nucleo-F411RE | STM32 Nucleo-F411RE | open | Open ⛶ | |
| Button toggles LD2 | STM32 Nucleo-F411RE | STM32 Nucleo-F411RE | open | Open ⛶ | |
| USART2 Serial (ST-Link VCP) | STM32 Nucleo-F411RE | STM32 Nucleo-F411RE | open | Open ⛶ | |
| Timer Blink (TIM2) | STM32 Nucleo-F411RE | STM32 Nucleo-F411RE | open | Open ⛶ |
Chips
Notes
Embedding
This is a two-layer stack: a real ARM CPU core underneath, and a from-scratch STM32F411 SoC + NUCLEO-F411RE board on top. It loads real Cortex-M4 flash images and runs them on the actual on-chip peripherals — RCC clock gating, the GPIO ports, USART2 and the TIM2 timer — at their real addresses. The firmware is genuine compiled machine code, not a shim.
- The CPU.
cortex-m7.jsexecutes Thumb-2 plus the FPv5 VFP. The real chip is a Cortex-M4F (ARMv7E-M with an FPU); this core is the same ARMv7-M family, so it runs the M4 image unchanged. - Real reset. The image is a real flash image with the ARM vector table at
0x08000000: on reset the board loadsSPfrom word 0 andPCfrom word 1, exactly like the silicon. - The board, in JavaScript.
nucleo-f411-board.jsmaps FLASH/SRAM/peripherals at their real STM32F411 addresses, answers the RCC clock-ready bits the firmware spins on, folds each GPIOBSRRintoODR, drives the button level intoGPIOC->IDR, captures every byte written toUSART2->DRinto the serial console, and counts TIM2.
| Piece | Kind | What it does |
|---|---|---|
NucleoF411.create(canvas) | factory | Build the ARM core + the STM32F411 memory map + peripherals. |
load(bytes) / reset() | method | Copy the flat image into FLASH; reset loads SP/PC from the vector table at 0x08000000. |
runFrame() | method | Step ~60k instructions and advance the TIM2 timer. |
setButton(down) | input | Drive the blue user button B1 (PC13) level low while held. |
ledOn() / getSerial() | method | The on-board LED (LD2, PA5, active-high) state and the accumulated USART2 output. |
Debugger integration
nucleo-f411-debug.js reads window.EMU_BOOT and hands the shared debugger a genuine ARM Cortex-M4F machine — the same core the firmware runs on, exposed instruction-accurately.
- Registers.
registers()reads r0-r12, SP, LR, PC, xPSR and the APSR flags N/Z/C/V live each refresh, plus the FPU single-precision registers s0-s31; r0-r15 and the flags each have aset()that writes straight back into the core's register file. - Disassembly. FLASH is decoded with the shared
cortex-m7decoder (the Thumb-2 disassembler), so the code window shows real ARM mnemonics at the real reset address0x08000000. - Single-step. Step calls
transport.stepInsn, which advances the core exactly one Thumb instruction; PC and the registers update after each step. You can watch the reset handler copy.datato SRAM and fall intomain(). - Breakpoints & watchpoints. Execution breakpoints are a PC set the run-loop checks before each instruction; write watchpoints wrap the board's memory-write path and pause when a watched address is written (e.g.
GPIOA->ODRat0x40020014orUSART2->DRat0x40004404). Both are real. - Memory map. Three chips read the real address space side-effect-free: FLASH (program, disassembled, 0x08000000), SRAM (0x20000000), and the peripheral block (0x40000000 — TIM2, USART2, GPIOA-C, RCC). Reading the dynamic registers (USART2 SR, GPIO IDR incl. the live button on PC13) is side-effect-free.
- Input. The blue user button B1 is in the shared Controller panel; pressing it drives
GPIOC->IDRbit 13 low, exactly as the hardware button does.
Architecture
The ST NUCLEO-F411RE is STMicroelectronics' popular low-cost developer board built around the STM32F411RE — a 100 MHz ARM Cortex-M4F (ARMv7E-M, with a single-precision FPU) with 512 KB flash and 128 KB SRAM — with an on-board ST-Link debugger/programmer. This build models the chip from scratch on the shared ARM core.
- Cortex-M4F CPU — runs the real Thumb-2 image. FLASH is at
0x08000000(the vector table: word0 = initial SP, word1 = reset handler), SRAM at0x20000000, all peripherals at0x40000000. On reset SP and PC are loaded from the vector table, exactly as on silicon. - RCC (Reset & Clock Control,
0x40023800) — the firmware gates each peripheral's clock throughAHB1ENR/APB1ENR/APB2ENRbefore touching it, and spins on the clock-ready bits (HSIRDY,HSERDY,PLLRDY); the board answers those bits so real clock-setup code proceeds. - GPIO ports A/B/C — the STM32F4
MODERmode,PUPDRpull,IDRinput,ODRoutput and the atomicBSRRset/reset register (low 16 bits set, high 16 bits reset). The green user LED LD2 is on PA5 and is active-high (lit whenGPIOA->ODRbit 5 is high); the blue user button B1 is on PC13 and is active-low (a pull-up idles it high; pressing pullsGPIOC->IDRbit 13 low). - USART2 (
0x40004400) — the serial port routed to the ST-Link virtual COM port (TX = PA2).SRkeepsTXE/TCasserted so polling transmit code runs, and every byte written toDRis captured onto the on-screen serial console. - TIM2 — a general-purpose 32-bit timer used here as 16-bit: prescaler (
PSC), auto-reload (ARR), counter (CNT),EGR.UGforce-update and the update flag (SR.UIF), advanced by executed instructions; the Timer Blink program times the LED off TIM2. SysTick and the NVIC come from the core. - Content. Four original CC0 bare-metal C programs compiled with clang for thumbv7em: Blink LD2, Button toggles LD2, USART2 Serial and Timer Blink (TIM2). No proprietary firmware is used.
- Honest limits. A Nucleo has no on-board audio (no speaker/DAC), so this emulator is genuinely silent with no sound path. USB, ADC, SPI/I2C, DMA and the interrupt-driven paths of the untouched peripherals are not modelled — the bundled firmware polls.