AN3208

Software

Doc ID 17411 Rev 1

13/19

5

Software

5.1

Preliminary information

The software described in this section has been implemented using a 32-Kbyte

STM8AF6266 device with 32 pins. It performs the complete needle rotation of one stepper

motor (in a forward and back forward direction).

Two PWM channels and two I/O lines are necessary for driving the stepper motor.

Thus, four stepper motors can be driven by STM8AF6266 devices as it is able to provide up

to eight PWM signals.

Note:

Up to four PWM signals are provided by TIM1, two PWM signals are provided by TIMER2

(leaving one channel free ), and another two PWM signal are provided by TIMER3.

5.2

Software description

The software code is based on the STM8A/S standard firmware library available from

http://www.st.com.

The firmware consists of:

●

A main program

●

An interrupt routine.

TIM1 interrupt routine, (TIM1_UPD_OVF_TRG_BRK_IRQHandler()), is used for providing

PWMs signals with correct duty cycles.

5.2.1

Main program

The main program initializes the peripherals (GPIOs, timers, clock CNTRL), the variables,

and the interrupt routines. After initialization, it stays in an endless loop (see Figure 12).