This L6470 chip from ST has SPI interface to control stepper motors. It accepts high level commands, like step x count left and ramp down! It has built in analog and digital inputs to aid in making stepper controller and can control medium size motors, perfect fro 3D printer or laser cutter. It even has a built in regulator so you do not need 3.3V, just give it ht motor voltage and it is happy!
Of course this chip is perfect for NETMF as it handles all the stepping automatically from SPI commands.
Let us know what you think and if this interests you please.
Any volunteers to write the drivers? We will get you a free board of course to play with.
[quote=“GMod”]MegaStepper
Stepper motor driver for upto 4 motors. Motors up to 3A, 8V to 45V, although the initial board will be limited to 16V, I can customise it for higher voltages on request. Built in Limit Switch interface for each motor. Convenient ribbon cable between board and motor. At motor there is a ribbon breakout board for motor and limit switch. Uses one L6570 for each motor. Mounting holes for heatsink, should it be deemed to be required, which will then be included.[/quote]
We build a pcb with 4 L6470 and a 8051-processor.
Its not easy to find the correct configuration for the different stepper motors. But when configuration is OK, the resulting movements are genius.
Maybe we will try the L6480, but (unfortunately) at the moment I have no project for it…
Perfect, yes the chip has a “Sensorless stall detection” with a programmable current comparator
In my next Application i do not have a end/start switch, to determine at startup which position the vavle has. So I will drive it in close position until it stall’s.
How are the user going to find the correct values for the bemf settings etc?
This is why I canned my module. Because the users will have a hard time to find the correct setup for their motors. I still have not found a setup for my motors that does not go into harmonics, or something, at higher speeds…
I guess you are trying to tell me that this is not easy to do?
I have a need to drive a stepper motor, I saw the driver for the module in the latest code drop and wondered when the module would be available. If you have some useful info on the topic I would be very interested to hear since I am wanting a stepper motor driver.
ST has some software that can give you the basic setup values, but even their engineers say that this should only be the starting point for the paremters. They then need to be tuned by hand while measuring the current going to the motor.
@ GMod(Errol) - Am I understanding correctly that using a module based on the L6470 I would ideally need an oscilloscope to tune the parameters? If so, wow, thank you for warning me!!! I would have had a useless module on my hands, there will need to be a big reg bold warning on the module when it ships.
Gus, you can do very basic setup without a scope, but it is easy to ruin the steppe that way by running at too high a current
For basic setup you need to know the back Eng of the stepper. This is not in the stepper’s datasheet and must be measured with a scope.
Then you can feed said bemf, coil inductance, coil resistance and step speed into the ST app to get the basic setup values.
There is a “simpler” chip from ST that uses current regulation in stead of voltage regulation. But it only has 16 micro steps compared to this chip’s 128 microsteps, and it has no stall detection.
It is pin compatible, but it’s registers are not the same. I can’t give a chip number as I’m on a phone, but I think its l6474.
OK so I need a scope, for the hardware challenged software developer, any recomendations? Santa might be looking for a scope to put under the Christmas tree.
[quote=“GMod(Errol)”]
But the gadgeteer current sensor module might be made to work too…
[/quote]I’m still having trouble getting that module too work at all.
Hi,
I have designed and have been selling an L6472 based unit that is far simpler than the L6470. You just tell the chip what current to drive the motors at for accel, decel, and normal running. No messing with BEMF, etc. See below: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230891366885
First one done wins!
