redboard: SparkFun RedBoard - Programmed with Arduino - DEV-13975 - SparkFun Electronics
Qwiic Step: Qwiic Step - SPX-15951 - SparkFun Electronics
Qwiic Step board should be the board controlling all the motors
On the page it says:
"Most powerful of all, Qwiic Step has a configurable I2C address. This means you can control over 100 stepper motors from a single microcontroller (but you’re going to need a heck of a power supply!)."
I assume it can run multiple motors, but I don't know how to connect them
then under Qwiic Step library, Example14_MultipleMotors, **it says I need to attach the second Qwiic Step with another motor. **
so I'm confused about whether it can run multiple or not.
or maybe I misunderstood something.
1 board - 1 motor
1 Arduino can access 127 I2C devices, so yes, 1 of these to 1 motor.
There are stepper boards running 3 steppers managing some 1.5 Amp per motor. Cooling fan needed.
The Qwiic Step has an A4988 chip on it, which will run only one stepper at a time. You will need one Qwiic Step per motor, each Qwiic Step assigned a different I2C address.
Furthermore, the A4988 will provide at most 1 Ampere per winding, unless you have forced air cooling, so choose your stepper carefully and make sure you set the current limit correctly.
jremington:
The Qwiic Step has an A4988 chip on it, which will run only one stepper at a time. You will need one Qwiic Step per motor, each Qwiic Step assigned a different I2C address.
Furthermore, the A4988 will provide at most 1 Ampere per winding, unless you have forced air cooling, so choose your stepper carefully and make sure you set the current limit correctly.
clear and neat answer for a newbie like me
Really appreciate
What do you mean per winding?
say if I'm going to set up two motors (so each has 1 qwiic step and a motor)
then the power source for each of the motor cannot be larger than 1 Amp?
jremington:
The Qwiic Step has an A4988 chip on it, which will run only one stepper at a time. You will need one Qwiic Step per motor, each Qwiic Step assigned a different I2C address.
Furthermore, the A4988 will provide at most 1 Ampere per winding, unless you have forced air cooling, so choose your stepper carefully and make sure you set the current limit correctly.
I might be mistaken but I think my Protooner V3 board, housing 3 drivers, uses A4988 drivers that handles 1.5 Amp using a heatsink. They will get warm (hot) but using a little 12 volt, 2" fan, it runs forever.
What do you mean per winding?
Stepping motors and motor drivers are rated by the maximum continuous current per winding. There are usually two windings.
then the power source for each of the motor cannot be larger than 1 Amp?
Devices DRAW current, and the power supply must be rated to provide more than the total current draw of all the devices.
With stepping motors the story is a bit more complicated than that, but for two motors/drivers that each draw 1 Ampere per winding, it is simplest to buy a motor power supply that can provide at least 4 A.
The unusual complication with steppers is that the higher the power supply voltage, the less average current the motor/driver draws, so a 19V 3A laptop power brick might work out OK.
jremington:
The Qwiic Step has an A4988 chip on it, which will run only one stepper at a time. You will need one Qwiic Step per motor, each Qwiic Step assigned a different I2C address.
I know this question is a bit dumb
but how do you know it can only run one stepper?
Just curious about it
Really appreciate!
Stepper motor has 4 wires, the output on the A4988 has 4 connections, and the Datasheet also tells you this. 
In principle you could wire two small steppers in parallel to the A4988, but they will not be independent, and will split the available power (maximum about 0.5 Amperes per winding each) to step at exactly the same time.
If that seems useful, fine. But first, learn how to work with one stepper. They have many limitations compared to other types of motors.
jremington:
In principle you could wire two small steppers in parallel to the A4988, but they will not be independent, and will split the available power (maximum about 0.5 Amperes per winding each) to step at exactly the same time.
If that seems useful, go for it.
I wonder if that is safe. Suppose the inductance-resistance differ a bit between the two motors. Then the power distribution will not be equal. When they rn they will run the same fast but the torque available might not be the same.
I wonder if that is safe.
What safety issues do you imagine?
The same argument could be made with brushed DC motors, but people very frequently connect those in parallel, for example on each side of a 4WD vehicle.
I've never heard of anyone having a problem with such a connection.
jremington:
What safety issues do you imagine?
The same argument could be made with brushed DC motors, but people very frequently connect those in parallel, for example on each side of a 4WD vehicle.
I've never heard of anyone having a problem with such a connection.
Running steppers I assumed current limiting is used. PWM has no current limitation, playing tricks.
I know that serially produced steppers have very much the same internal data but if an ignorant member combines 2 more or less different motors, phenomena are not unlikely.