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blog_3 [2017/01/25 18:26] arthur |
blog_3 [2017/01/25 18:35] (current) arthur |
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| - | The [[[Smoothie]]] project will use the [[http://www.allegromicro.com/en/Products/Part_Numbers/4983/4983.pdf|Allegro A4983]] chip to drive the stepper motors. | + | The [[Smoothie]] project will use the [[http://www.allegromicro.com/en/Products/Part_Numbers/4983/4983.pdf|Allegro A4983]] chip to drive the stepper motors. |
| It's a very nice chip, it has 1/16 microstepping, can drive up to 2A, and has the simple step/direction interface. | It's a very nice chip, it has 1/16 microstepping, can drive up to 2A, and has the simple step/direction interface. | ||
| - | Most common way to use it is via the [[http://www.pololu.com/catalog/product/1201|Pololu Driver Carrier]], but in the case of [[[Smoothie]]], we want all of the 4 drivers directly on the PCB, so that they can share the heatsink/fan, and also share some components. | + | Most common way to use it is via the [[http://www.pololu.com/catalog/product/1201|Pololu Driver Carrier]], but in the case of [[Smoothie]], we want all of the 4 drivers directly on the PCB, so that they can share the heatsink/fan, and also share some components. |
| Before designing the Smoothie PCB, it's important to be sure how exactly the A4983 works. | Before designing the Smoothie PCB, it's important to be sure how exactly the A4983 works. | ||
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| A few notes : | A few notes : | ||
| * The dir pin is connected to +5V so it only goes one way, that's just because this is a test, just connect it to an arduino digital output, and you can change directions. | * The dir pin is connected to +5V so it only goes one way, that's just because this is a test, just connect it to an arduino digital output, and you can change directions. | ||
| - | * 3 resistors are missing, if compared to the example in the datasheet. That's because as [[[Smoothie]]] will be USB-powered, we assume the power supply can be trusted. It reduces cost, and gives more free space around the chips ( there need to be no other component around the 4 A4983 so that they can be directly in contact with the heatsink. | + | * 3 resistors are missing, if compared to the example in the datasheet. That's because as [[Smoothie]] will be USB-powered, we assume the power supply can be trusted. It reduces cost, and gives more free space around the chips ( there need to be no other component around the 4 A4983 so that they can be directly in contact with the heatsink. |
| That's all for today. | That's all for today. | ||
| Next step : controlling the current setting of the A4983 with the MCP4331 digital potentiometer. | Next step : controlling the current setting of the A4983 with the MCP4331 digital potentiometer. | ||
