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mbueno2k

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  • GeraldZ1,I like this. I'm considering using a low-power 555 to pulse a stepper motor *driver*, (like the drv8825, tcm2100, or tcm2130) so I can drive my stepper driver from the 555, thereby offloading the pulse-generation from my microcontroller (using esp8266). My intention is to free the microprocessor from any incurred blocking imposed upon it while moving the motor. I will use a pin-interrupt to detect how many steps have been taken (aka pulses generated by the 555 as the stepper motor moves). I then plan to implement a variety of stepper speeds (to accelerate and decelerate) using a digital potentiometer in place of R2 in the basic 555 circuit. What I don't know yet is how long it will take me to change the digital pot's resistance (via i2c, I suppose). I plan to only vary the r…

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    GeraldZ1,I like this. I'm considering using a low-power 555 to pulse a stepper motor *driver*, (like the drv8825, tcm2100, or tcm2130) so I can drive my stepper driver from the 555, thereby offloading the pulse-generation from my microcontroller (using esp8266). My intention is to free the microprocessor from any incurred blocking imposed upon it while moving the motor. I will use a pin-interrupt to detect how many steps have been taken (aka pulses generated by the 555 as the stepper motor moves). I then plan to implement a variety of stepper speeds (to accelerate and decelerate) using a digital potentiometer in place of R2 in the basic 555 circuit. What I don't know yet is how long it will take me to change the digital pot's resistance (via i2c, I suppose). I plan to only vary the resistance of the pot occasionally during accel/deceleration so as to minimize the stepper driver wait time, hopefully minimizing stepper choppiness during accel/deceleration.Since I'm using an esp8266-based microprocessor (actually a wemos d1 mini pro), it will be busy in the background doing all its WiFi stuff, and although I haven't tested it just yet, I expect that when I enable WiFi, it will cause the stepper motor to pause during movement when all the WiFi stuff happens. Let's face it, the esp8266 does *a lot* in the background, behind the scenes. The timing necessary to drive a stepper motor while it's moving is critical. This probably isn't the best microprocessor for the job.Another possible solution would be to use a second microprocessor just to drive the stepper, and communicate between processors via serial. This way the esp8266 could do the WiFi, and the arduino or attiny or whatever could do the stepping. This would in some ways be cleaner, and would eliminate lots of unknowns with respect to stepper driver timing,but where's the fun in that? Tinkering is fun, and if it works with the 555/digital pot, it will be pretty cool...Thanks for sharing your project!!! It has inspired me to consider pursuing using a 555 in my project!

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