add STM32 backend (STM32duino / Arduino_Core_STM32)

.github/workflows/build_arduino_examples_matrix.yml

@@ -10,10 +10,6 @@ on:
   pull_request:
     branches: [ master ]
 
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
-  cancel-in-progress: true
-
 jobs:
   build:
     strategy:
@@ -80,6 +76,11 @@ jobs:
           - atmelsam
           - rpipico
           - rpipico2
+          - bluepill_f103c8
+          - nucleo_g070rb
+          - blackpill_f401cc
+          - nucleo_h743zi
+          - nucleo_l476rg
 
     runs-on: ubuntu-latest
 

.github/workflows/build_idf_examples_matrix.yml

@@ -15,10 +15,6 @@ on:
   pull_request:
     branches: [ master ]
 
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
-  cancel-in-progress: true
-
 jobs:
   build:
     strategy:

README.md

@@ -639,6 +639,49 @@ Found on youtube:
 As mentioned by kthod861 in [Issue #110](https://github.com/gin66/FastAccelStepper/issues/110):
 * [22 01 2021 Stepper POC3](https://youtu.be/fm2_VkUG10k)
 
+## STM32 Arduino Support
+
+FastAccelStepper supports STM32 microcontrollers via the official
+[Arduino Core STM32](https://github.com/stm32duino/Arduino_Core_STM32).
+
+### Architecture
+
+- **Step generation**: TIM2 CC interrupt + BSRR/BRR GPIO (push-pull OUTPUT)
+- **Steppers**: Up to 4 (any GPIO pins, dynamic slot allocation)
+- **Pulse width**: 6 µs (configurable via `STEP_PULSE_WIDTH_US`)
+- **Cyclic fill**: PendSV exception, triggered from TIM2 ISR every 3ms via uwTick
+- **GPIO mode**: Standard push-pull OUTPUT (any GPIO pin works)
+- **Direction**: Atomic BSRR set/reset — not ODR XOR (race-free)
+- **Direction settling**: `_dir_delay_active` state machine, 30µs delay
+- **TIM2 clock**: Auto-detection with APB1 prescaler ×2 correction
+- **Interrupt safety**: PRIMASK save/restore (reentrant)
+- **SR handling**: Snapshot → clear all processed at once (rc_w0)
+- **PendSV**: `__attribute__((weak))` — FreeRTOS compatible
+
+### Default Pin Mapping
+
+| Stepper | Default Pin | Notes |
+|---------|-------------|-------|
+| 0 | PA0 | Any GPIO pin can be used |
+| 1 | PA1 | (PA0-PA3 are conventional only) |
+| 2 | PA2 | |
+| 3 | PA3 | |
+
+### ⚠ Warnings
+
+1. **No FreeRTOS** — PendSV is overridden (weak, FreeRTOS can override).
+2. **TIM2 is reserved** — Do not use TIM2 elsewhere.
+3. **HAL timebase must be SysTick** (default). uwTick is used for cyclic fill.
+4. **Do not call HAL_Delay() with steppers running** — TIM2 priority 0 may preempt SysTick. Use millis() polling.
+5. **TICKS_PER_S must match TIM2 counter clock** — Define before library includes:
+   ```cpp
+   #define TICKS_PER_S 72000000UL  // STM32F103 @72MHz
+   #include <FastAccelStepper.h>
+   ```
+   See `pd_stm32/pd_config.h` for examples for each board.
+6. **Clock error**: After `engine.init()`, check `fas_stm32_clock_error`:
+   if non-zero, `TICKS_PER_S` exceeds actual TIM2 clock.
+
 ## Contribution
 
 - Thanks ixil for pull request (https://github.com/gin66/FastAccelStepper/pull/19) for ATmega2560

extras/StepperPins_stm32.h

@@ -0,0 +1,34 @@
+#ifndef STEPPERPINS_STM32_H
+#define STEPPERPINS_STM32_H
+
+// ====================================================================
+// Default step pin mapping for STM32 platforms
+//
+// These defaults map steppers 0-3 to PA0-PA3 (TIM2 channels 1-4).
+// Override by defining before including this header:
+//
+//   #define STEP_PIN_STEPPER_0 PB0
+//   #include "StepperPins_stm32.h"
+//
+// Note: On STM32, any GPIO pin can be used as a step pin.
+// PA0-PA3 are only a convention — the timer is used only for
+// interrupt timing, not direct pin output.
+// ====================================================================
+
+#ifndef STEP_PIN_STEPPER_0
+#define STEP_PIN_STEPPER_0 PA0
+#endif
+
+#ifndef STEP_PIN_STEPPER_1
+#define STEP_PIN_STEPPER_1 PA1
+#endif
+
+#ifndef STEP_PIN_STEPPER_2
+#define STEP_PIN_STEPPER_2 PA2
+#endif
+
+#ifndef STEP_PIN_STEPPER_3
+#define STEP_PIN_STEPPER_3 PA3
+#endif
+
+#endif /* STEPPERPINS_STM32_H */

extras/ci/build_matrix.yaml

@@ -152,6 +152,12 @@ templates:
     framework: arduino
     lib_extra_dirs: .
 
+  stm32:
+    platform: ststm32
+    framework: arduino
+    build_flags: ["-Wall"]
+    lib_extra_dirs: .
+
 environments:
   esp32:
     template: esp32_arduino
@@ -285,6 +291,31 @@ environments:
     board_upload_psram_length: 1048576
     build_flags: ["-D__FREERTOS=1"]
 
+  bluepill_f103c8:
+    template: stm32
+    board: bluepill_f103c8
+    build_flags_extra: ["-DTICKS_PER_S=72000000UL"]
+
+  nucleo_g070rb:
+    template: stm32
+    board: nucleo_g070rb
+    build_flags_extra: ["-DTICKS_PER_S=64000000UL"]
+
+  blackpill_f401cc:
+    template: stm32
+    board: blackpill_f401cc
+    build_flags_extra: ["-DTICKS_PER_S=84000000UL"]
+
+  nucleo_h743zi:
+    template: stm32
+    board: nucleo_h743zi
+    build_flags_extra: ["-DTICKS_PER_S=240000000UL"]
+
+  nucleo_l476rg:
+    template: stm32
+    board: nucleo_l476rg
+    build_flags_extra: ["-DTICKS_PER_S=80000000UL"]
+
 versioned_environments:
   esp32:
     prefix: esp32
@@ -429,6 +460,11 @@ workflows:
       - atmelsam
       - rpipico
       - rpipico2
+      - bluepill_f103c8
+      - nucleo_g070rb
+      - blackpill_f401cc
+      - nucleo_h743zi
+      - nucleo_l476rg
     script: build-platformio.sh
 
   idf:

extras/ci/platformio.ini

@@ -195,6 +195,41 @@ build_flags = -D__FREERTOS=1
 lib_extra_dirs = .
 board_upload.psram_length = 1048576
 
+[env:bluepill_f103c8]
+platform = ststm32
+board = bluepill_f103c8
+framework = arduino
+build_flags = -Wall -DTICKS_PER_S=72000000UL
+lib_extra_dirs = .
+
+[env:nucleo_g070rb]
+platform = ststm32
+board = nucleo_g070rb
+framework = arduino
+build_flags = -Wall -DTICKS_PER_S=64000000UL
+lib_extra_dirs = .
+
+[env:blackpill_f401cc]
+platform = ststm32
+board = blackpill_f401cc
+framework = arduino
+build_flags = -Wall -DTICKS_PER_S=84000000UL
+lib_extra_dirs = .
+
+[env:nucleo_h743zi]
+platform = ststm32
+board = nucleo_h743zi
+framework = arduino
+build_flags = -Wall -DTICKS_PER_S=240000000UL
+lib_extra_dirs = .
+
+[env:nucleo_l476rg]
+platform = ststm32
+board = nucleo_l476rg
+framework = arduino
+build_flags = -Wall -DTICKS_PER_S=80000000UL
+lib_extra_dirs = .
+
 [env:esp32_V6_13_0]
 platform = espressif32 @ 6.13.0
 board = esp32dev

library.properties

@@ -3,10 +3,10 @@ version=1.2.5
 license=MIT
 author=Jochen Kiemes <jochen@kiemes.de>
 maintainer=Jochen Kiemes <jochen@kiemes.de>
-sentence=A high speed stepper library for Atmega 168/168p/328/328p (nano), 32u4 (leonardo), 2560, ESP32, ESP32S2, ESP32S3, ESP32C3, ESP32C6, Atmel SAM Due, Raspberry pi pico and pico 2
-paragraph=Drive stepper motors with acceleration/deceleration profile up to 50 kSteps/s (Atmega) and 200kSteps/s (esp32).
+sentence=A high speed stepper library for Atmega 168/168p/328/328p (nano), 32u4 (leonardo), 2560, ESP32, ESP32S2, ESP32S3, ESP32C3, ESP32C6, Atmel SAM Due, Raspberry pi pico and pico 2, and STM32
+paragraph=Drive stepper motors with acceleration/deceleration profile up to 50 kSteps/s (Atmega) and 200kSteps/s (esp32). Supports STM32F1/F4/G0/H7 series via STM32duino core.
 url=https://github.com/gin66/FastAccelStepper
 repository=https://github.com/gin66/FastAccelStepper.git
-architectures=avr,esp32,sam,rp2040,rp2350
+architectures=avr,esp32,sam,rp2040,rp2350,stm32
 category=Device Control
-dot_a_linkage=true
+dot_a_linkage=true

src/fas_arch/arduino_stm32.h

@@ -0,0 +1,21 @@
+#ifndef FAS_ARCH_ARDUINO_STM32_H
+#define FAS_ARCH_ARDUINO_STM32_H
+
+#define FAS_STM32
+
+#include <Arduino.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+// PRIMASK reentrant-safe interrupt control
+// Saves and restores PRIMASK to support nested disable/enable calls
+#define fasDisableInterrupts() \
+  uint32_t __fas_prim = __get_PRIMASK(); __disable_irq()
+#define fasEnableInterrupts() \
+  __set_PRIMASK(__fas_prim)
+
+#define FAS_PSTR(s)  (s)
+// PIN_UNDEFINED (255) and PIN_EXTERNAL_FLAG (128) are defined in
+// FastAccelStepper.h. Do NOT redefine here to avoid -Wmacro-redefined.
+
+#endif /* FAS_ARCH_ARDUINO_STM32_H */

src/fas_arch/common.h

@@ -94,6 +94,11 @@ struct queue_end_s {
 #include "fas_arch/arduino_rp_pico.h"
 #include "pd_pico/pd_config.h"
 
+#elif defined(ARDUINO_ARCH_STM32)
+// STM32 family (STM32duino core)
+#include "fas_arch/arduino_stm32.h"
+#include "pd_stm32/pd_config.h"
+
 #else
 #error "Unsupported devices"
 #endif

src/fas_queue/stepper_queue.h

@@ -19,6 +19,8 @@
 #include "pd_pico/pico_queue.h"
 #elif defined(SUPPORT_ESP32)
 #include "pd_esp32/esp32_queue.h"
+#elif defined(FAS_STM32)
+#include "pd_stm32/stm32_queue.h"
 #else
 #error "Unsupported architecture"
 #endif

src/fas_ramp/RampCalculator.h

@@ -18,6 +18,97 @@
 #define LOG2_ACCEL_FACTOR LOG2_CONST_2205E11
 #define US_TO_TICKS(u32) ((u32) * 21)
 #define TICKS_TO_US(u32) ((u32) / 21)
+#elif (TICKS_PER_S == 32000000L)
+// STM32L0, RP2040
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x31dd)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x30dd)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x61ba)
+#define US_TO_TICKS(u32)                ((u32) * 32)
+#define TICKS_TO_US(u32)                ((u32) / 32)
+#elif (TICKS_PER_S == 48000000L)
+// STM32F0/G0/WL
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x3308)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x3208)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x6411)
+#define US_TO_TICKS(u32)                ((u32) * 48)
+#define TICKS_TO_US(u32)                ((u32) / 48)
+#elif (TICKS_PER_S == 64000000L)
+// STM32G0/WB
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x33dd)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x32dd)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x65ba)
+#define US_TO_TICKS(u32)                ((u32) * 64)
+#define TICKS_TO_US(u32)                ((u32) / 64)
+#elif (TICKS_PER_S == 72000000L)
+// STM32F1/L1 (most common)
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x3434)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x3334)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x6668)
+#define US_TO_TICKS(u32)                ((u32) * 72)
+#define TICKS_TO_US(u32)                ((u32) / 72)
+#elif (TICKS_PER_S == 80000000L)
+// STM32L4
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x3482)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x3382)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x6704)
+#define US_TO_TICKS(u32)                ((u32) * 80)
+#define TICKS_TO_US(u32)                ((u32) / 80)
+#elif (TICKS_PER_S == 84000000L)
+// STM32F401/411
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x34a6)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x33a6)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x674c)
+#define US_TO_TICKS(u32)                ((u32) * 84)
+#define TICKS_TO_US(u32)                ((u32) / 84)
+#elif (TICKS_PER_S == 100000000L)
+// STM32F411/746
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x3527)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x3427)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x684d)
+#define US_TO_TICKS(u32)                ((u32) * 100)
+#define TICKS_TO_US(u32)                ((u32) / 100)
+#elif (TICKS_PER_S == 120000000L)
+// STM32L4+/F4
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x35ad)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x34ad)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x695a)
+#define US_TO_TICKS(u32)                ((u32) * 120)
+#define TICKS_TO_US(u32)                ((u32) / 120)
+#elif (TICKS_PER_S == 168000000L)
+// STM32F405/407
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x36a6)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x35a6)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x6b4c)
+#define US_TO_TICKS(u32)                ((u32) * 168)
+#define TICKS_TO_US(u32)                ((u32) / 168)
+#elif (TICKS_PER_S == 170000000L)
+// STM32F3/G4
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x36af)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x35af)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x6b5e)
+#define US_TO_TICKS(u32)                ((u32) * 170)
+#define TICKS_TO_US(u32)                ((u32) / 170)
+#elif (TICKS_PER_S == 216000000L)
+// STM32F7
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x375f)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x365f)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x6cbe)
+#define US_TO_TICKS(u32)                ((u32) * 216)
+#define TICKS_TO_US(u32)                ((u32) / 216)
+#elif (TICKS_PER_S == 480000000L)
+// STM32H7 (default)
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x39ad)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x38ad)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x715a)
+#define US_TO_TICKS(u32)                ((u32) * 480)
+#define TICKS_TO_US(u32)                ((u32) / 480)
+#elif (TICKS_PER_S == 550000000L)
+// STM32H7 (overclock)
+#define LOG2_TICKS_PER_S               ((log2_value_t)0x3a12)
+#define LOG2_TICKS_PER_S_DIV_SQRT_OF_2 ((log2_value_t)0x3912)
+#define LOG2_ACCEL_FACTOR               ((log2_value_t)0x7224)
+#define US_TO_TICKS(u32)                ((u32) * 550)
+#define TICKS_TO_US(u32)                ((u32) / 550)
 #else
 #define SUPPORT_LOG2_TIMER_FREQ_VARIABLES
 #define LOG2_TICKS_PER_S log2_timer_freq