I2C Controlled Stepper Motor

[niekerk]

Hi rei_vilo,

Could you tell us about the pro's and cons of your solution, compared to just the
regular fischertechnik interfaces?

Paul

[vleeuwen]

Hi Paul,
This stepper control is amazing powerful. I already publish the information some years ago.
See for more info my stepper pages

The Amis stepper control has:
-) Current control with two levels Irun and Ihold,
-) The step frequency (speed) is adjustable,
-) Temp,. and error control,
-) micro stepping,
-) position control,
-) start and stop speed (de)acceleration control, this to avoid over shoting,
-) The current control makes it possible to get the maximum out torque out of the original fischertechnik stepper motor,
-) Only 9 passive component are needed to implement the cirquit.

This stepper control is my test case for the functional test of the fischertechnik I2C connectivity.
However, It was not possible to use it with the beta version of the fischertechnik I2C implementation.
The I2C commands need maximum of 7 bytes.


PRODUCT FEATURES AMIS−30622
Motor Driver
• Micro−Stepping Technology
• Peak Current Up to 800 mA
• Fixed Frequency PWM Current−Control
• Automatic Selection of Fast and Slow Decay Mode
• No external Fly−back Diodes Required
• 14 V/24 V Compliant
• Sensorless stall detection(AMIS−30624)
Controller with RAM and OTP Memory
• Position Controller
• Configurable Speeds and Acceleration
• Input to Connect Optional Motion Switch
I2C Interface
• Bi−Directional 2−Wire Bus for Inter IC Control
• Field Programmable Node Addresses
• Full Diagnostics and Status Information
Protection
• Overcurrent Protection
• Undervoltage Management
• Open−circuit Detection
• High Temperature Warning and Management
• Low Temperature Flag

[niekerk]

@Carel: yes, lots of possibilities.

@rei_vilo: which of these features did you actually put to use, in the video?
It doesn't look particularly fast.

[vleeuwen]

Couple of remarks:

At normal operation the Irun needs to be higher than the Ihold
The Ihold is needed to keep position but it also heat the coil of the stepper motor.
So keep the Ihold as low as possible.

At the other hand the Irun does move the load. For that you will need extra torque.
To avoid skid (missing of a step, inaccuracy), the Irun needs to be enough to be sure that the step or microstep will be a success.
My experiance is that one FT-power supply (1A 9V) for each stepper motor (two coils) is a little bit to weak to get the maximum out of an original FT- steppermotor. You will need at least 1.2 A 9V.