User Manual

AND8399/D

http://onsemi.com

Timer Overflow ?

Power Up

Initialize microcontroller

Set Coil Current

Set Stepping Mode

Enable Motor

Transparent Mode

Send NXT Pulse

Start Timer

If MSP =

(0 OR 32 OR 64

Delay

Sample SLA−pin

Read Microstep

Position

SLA below

Threshold ?

Stop

Figure 25. Simple Stall Detection

OR 96)

SLA Check

With the flowchart given in Figure 25 we are able to

sample the SLA voltage in a correct way and to perform

simple stall detection. The only issue that could occur is an

offset. If for some reason an offset is created, no microstep

will be located anymore on the coil current zero crossing.

The SLA voltage can not be sampled nor can stall detection

be done.

Figure 26 gives a simple solution to this problem. If an

offset is detected, motion is stopped. In a real life application

the microcontroller could do corrective actions or report the

problem. This is out of the scope of this document.