Re: Microstepping or gearbox... #EQ5 #esp32 #bluepill


George Cushing
 

To Mark's point most of the controllers used with 24 and 48 steppers used in the TruTrac and Vixen DD systems are limited to 16 or 32X speeds. 

Many Vixen owners ask me if they can use OnStep goto with their MT-1 drives with 120:1 gearheads (GR1). I have to tell them no, only sloto. The MT-1 is limited to 350 pulses a second or 0.35kHz. Run that through Howard's config calculator and you'll see that sloto equals 0.15°/second slew rate or 38.5X sidereal. so even with 32 bit processors running at 240MHz and drivers with their own microcontrollers we get only slightly faster max speeds.

The TruTracs use an 8 Atmel 89C2051 microcontroller, a derivative of the 1980 Intel 8051 microcontroller.. I will run at up to 24MHz, but the one I'm looking at has a 3.85MHz crystal. The flash memory is good for 2K Bytes. There is no driver as the steppers are driven by the 89C2051s general purpose in/out ports. 

The 89C2051 is a workhorse in the auto industry and is one of the chips in short supply. These chips sell for less than a quarter ($0.25) in quantity and there is very little profit in making them, which is the main reason for the shortage. Intel says it is going to spend billions on a new fab in AZ to meet the shortage. Doesn't sound like a good plan to me.

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