Posted on February 12, 2016 at 13:52Hello there,
I have noticed a while a go, that STM32 feature nice timers 1 and 8, which can be used for effective motor controll thanks to complementary outputs and deadtime mechanism. However, for some reason none of the STM32 devices has all 8 channel fully functional. What I mean is that only channel from 1 to 3 are ''enchanced'' and the channel 4 is left without complementary output and deadtime mechanism.
In this situation when I want to drive a stepper motor (need 4 complementary channels) I need to use channels 1-3 from TIM1 and channel 1 from TIM8... Thats no to bad but now I need to drive 2 motors... In this case it hurts that the 4th channel is poor. It would work just fine the mtors were BLDC or PMSM but they are stepping motors. Thats why I was wondering if I could just rely on the internal deadtime of high side driver, and get the negative complementary pwm output for channel 4 by using an external mosfet N channel.
Here I have drawn what I meant exacly:
https://dl.dropboxusercontent.com/u/14154631/poor_driver.jpg
Sorry for the poor schematic but youll get the idea. What I am wondering is- would there be any software problems in regard to this aproach? Since the high side driver has an internal 100ns dead time, would the poor 4th channel be any different from the 3 others?
I would apreciate all help!
