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bigtreetech / BIGTREETECH-S42B-V1.0

The closed-loop drive is to feedback the rotation angle of the stepping motor to the control panel, compare the distance that needs to be rotated with the distance of the actual rotation, calculate the error value, and then compensate, so as to prevent the problem of multi-step and lost step. The closed-loop drive can completely overcome the lost step of the open-loop stepping motor, and can also significantly improve the performance of the motor at high speed
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[FR] TMC stepper driver #6

Open Protean-Man opened 4 years ago

Protean-Man commented 4 years ago

What you have done is impressive with the integrated closed loop circut - but the A4950 is older and antiquated. What about the TMC4671 - ? Or other even two options with the TMC5160 & TMC2209?

frank-pian commented 4 years ago

These closed-loop drives are based on 'Nano Zero Stepper'. This code does not use the TMC chip.

dzid26 commented 4 years ago

What you have done is impressive with the integrated closed loop circut - but the A4950 is older and antiquated. What about the TMC4671 - ? Or other even two options with the TMC5160 & TMC2209?

This would be close loop control on chip instead of software.

They actually sell (expensive) close loop steppers. https://www.trinamic.com/products/pandrive-smart-motors/#c2483

garkin commented 3 years ago

This whole assembly is less than $20 atm. What makes A4950 antiquated in this price range?

What exactly your change adds to the plate? How much does it cost? What ammount of work required to update firmware? Mouser shows $30 per item TMC4671-LA datasheet

Protean-Man commented 3 years ago

In the usage of stepper drivers the A4950 compared to others, it is older and antiquated. This closed loop system is great and yes it is at a great price range for what you get.

My question still stands given that they could make create this for $20, why wouldn't they want to sell a version with more advanced drivers? The closed loop systems from TMC are very expensive - I'd bet Bigtreetech could do it for much cheaper and get similar quality.

fake-name commented 3 years ago

The TMC4671 is completely irrelevant here, because the servo controller is implemented in the STM32 MCU. Sure, you could replace the entire circuit with another, but at that point, it's just a different product.

In the usage of stepper drivers the A4950 compared to others, it is older and antiquated.

The A4950 is not a stepper driver, and it is not antiquated. It's a perfectly servicable modern single-chip current limited H-Bridge IC.

If you think the TMC4671 is a replacement or upgrade for the A4950 (and the way it's being used), you have no idea what you're talking about.

The entire point of doing the servo loop in a inexpensive MCU with a simple H-Bridge output stage is that it's inexpensive, and you can compensate for any hardware nonlinearities with clever software. The TMC4671 is the opposite of that.

dash3811 commented 3 years ago

If you want to use upgraded drivers for closed loop then you should just buy a SKR 1.4 or 1.4 Turbo and instead of connecting the wire to the adapter driver just connect it to the spot in front of the drivers labeled x-cls, y-cls, etc. That's the purpose of those pins.