Basic Unipolar Stepper Driver Object with Limit Switches

Basic driver object for a unipolar stepper motor with two limit switches using a FIFO command queue and separate cogs for the motor driver and switch monitor processes.

Nothing fancy, no acceleration / deceleration code is provided. Such code can be accomplished by the client process. For example to accelerate from minimum speed to maximum one may simply enqueue single step motor commands inside a dimishing time duration loop.

Tested using various salvaged unipolar stepper motors (5 and 12 volts) and custom driver boards for various "hobby" projects (eg: solar panel tracker, etc.)

Example usage code:

• `CON`

• ` _CLKMODE = XTAL1 + PLL16X 'Setting up the clock mode`

• ` _XINFREQ = 5_000_000 'Setting up the frequency`

• ` {Limit Switches}`

• ` LSWLpin = 0 ' 220Ω in series to 10k pullup to Vdd and SPST NO switch, active low`

• ` LSWRpin = 1 ' 220Ω in series to 10k pullup to Vdd and SPST NO switch, active low`

• ` {Unipolar Stepper Motor Driver}`

• ` SMphApin = 2 ' 220Ω output to MOSFET gate A`

• ` SMphBpin = 3 ' 220Ω output to MOSFET gate B`

• ` SMphA_pin = 4 ' 220Ω output to MOSFET gate /A`

• ` SMphB_pin = 5 ' 220Ω output to MOSFET gate /B`

• `OBJ`

• ` SM : "Stepper"`

• `PUB Main | delay`

• ` SM.Start(SMphApin,SMphB_pin)`

• ` SM.StartWatchLSws(LSWLpin,LSWRpin)`

• ` delay := (CLKFREQ/1000)* 8 ' mS`

• ` SM.EnqueueCmdArg(SM#REVERSE,false)`

• ` ' run until either limit switch is triggered`

• ` repeat while not SM.LSwStates`

• ` SM.EnqueueCmd(SM#SINGLE_STEP_AND_HOLD)`

• ` waitcnt(delay + cnt)`