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Gordie
Do you think it's possible?
The step/dir/enable lines on RAMPS-FD are all 3.3V. You driver requires 5V. You will need to provide level translation to get your signals levels up to 5V.
The A498x and DRV8825 drivers both support 3.3V operation for the control side, so they work as-is.
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Gordie
What are your suggestions on raching 1/64th with the RAMPS-FD?
Level shifting the signals to 5V if you want to use that driver, or find a driver that does 1/64th (or better) and supports 3.3V logic.
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Gordie
Is it true that 1/64th cannot be reached on classic Arduino (16Mhz) due to the low MCU's power calculation?
No. the 1/64th has nothing to do with the power in the CPU. It's all about the expectations of speed that people have for a machine. If you want 1/64th steps but want it as fast as 1/16th, then the CPU needs to work at least 4 times as hard, as it needs to generate 4 times as many pulses to achieve the same distance over a set time.
At 16 Mhz, we're pushing the little Atmel MCU's near their performance limit, especially with all the other stuff going on in the background, to achieve the speeds people "seem" to expect. With an ARM, we should be able to do more. The Arm also can do some of the other more intensive code (that isn't directly related to steps) faster as well, leaving more time to do steps.
Also, the driver itself needs to be able to accept that many pulses in that same time frame. Many of the TB drivers seem to require the pulse to be "on" for a lot longer than the A498x's and DRV8825's, which means that you can't send anywhere near as many pulses.
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Gordie
Or is something related to the Firmware?
One thing that will be related to firmware is that if you're using TB type drivers, they send to require a longer on-time. Some firmware out there supports this, some does not. Your mileage will vary.
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Gordie
Another point, I need to control some servos and other stuff for a project that I've in mind:
- Is it possible to connect another Arduino trhu the SPI port of the RAMPS-FD?
- If so, can I use the second Arduino board, connected trhu the SPI, to control servos and other things during the printing process?
Thanks to everybody :)
You will need to write the code on both sides, but yes, it should be possible.
This method is how bobc plans to add support for more than 6 steppers (adding another board connected via SPI). Note that you need to provide some sort of "clock" to synchronise the signals if you care about everything working at the same time. This mainly would apply to steppers, but even with servos, it may be necessary (depending on what exactly you're doing).
That said, RAMPS-FD provides 4 Servo outputs (though they're only 3.3V), so if you don't need any more and the servos will operate from 3.3V, you won't need to take stuff off board.