STM32Step

A simple motion control library, built from luni64's TeensyStep 2.0 library.
The main purpose is to keep and improve the original lib functionality, while porting it to STM32 HAL environment. A re-organization of the library is done to have a more intuitive structure (for me at least). Also the use of expensive abstractions (virtual functions) was eliminated and more accurate naming was introduced.

A possibility

While the library name implies STM32, maybe a platform independent version (UnifiedStep?) could emerge if there is demand. The main requirement seems to be a unified timer array API and a unified step generation API. This library provides a starting point for both (taking a lot from TeensyStep), maybe with some work it is achievable.

Overview

The functionality consists of timing, step generation and speed design (a.k.a. acceleration plan). Timing is outsourced to STM32TimerArray. Step generation has a fully software implementation, GPIOStepper represents a stepper motor and creates the waveforms with 'bit banging'. (A TIMStepper could also be added representing a stepper motor with hardware aided step generation.)

There are two modes of operation, SpeedControl and PositionControl. With SpeedControl acceleration is planned to transition between speeds. PositionControl as the name implies is focused on reaching target positions. Interactivity is not well supported yet, when a command is given it can't be canceled. For example a position command can't be interrupted halfway, to set a new target instead. Maybe some clever hacks enable that, but it should be built-in functionality.

Update

Platform conversion is done.
Basic functionality works, rigorous tests are still needed.

Versions

• @ Version 0.3.0
  First usable version.
  Basicaly a complete rewrite of TeensyStep for STM32 environment.
  Using STM32TimerArray for timing tasks.

TODO

• Adapt the timer sublibrary to STM32 platform
• Adapt GPIO handling
• Test functionality (only trial runs, no proper testing yet)
• Create a separate library from the timer sublibrary (STM32TimerArray)
• Adapt STM32Step to use the new timer library
• (Obsolete) Create hardware aided timer library with unchanged API (setup can differ)
• Measure performance (load, jitter, maximum performance) with different timer libs (STM32TimerArray, ported TickTimer)
• Create hardware aided step generator (use timer PWM or pulse generation capability)
• Complement GPIO based step generation, do not overwrite it
• Add functionality to improve motion control abilities (MotionControl class)
• Re-init target during command, without stopping or finishing acceleration
• Motion chain to support position control without the need to stop at every waypoint
• Arc movements? (might be useful for G-code based CNC applications, interpolation also works)