RAMPS/Marlin compatible Stepper Driver, 4 Amp 50 Volt (200 Watt) :
https://www.ecomorder.com/techref/ecomprice.asp?p=416074
One of the issues I hear about from RepRap people all the time is that the little Polulu stepper drivers (1 amp 35 volts) don’t have enough power to move larger motors fast enough. If you are making a bigger version of a 3D printer, or want to slam that bed back and forth faster, you need more power.
But, when people hook up other drivers to the RAMPs boards or anything running Marlin, the result is a mess: Massive missing steps. Why? Because the step pulse Marlin puts out is microscopic; only 1.88uS according to my scope. The Allegra A4983 drivers used on the Polulu’s only need 1uS step time as per page 6 of the datasheet:
https://www.pololu.com/file/download/a4983_DMOS_microstepping_driver_with_translator.pdf?file_id=0J199
Most drivers want at least a few micro seconds to catch the step signal. Some advise much more. For example, the ultra popular (but flawed) TB6560 drivers require 10uS /minimum/ and recommend 30 to 90uS as per page 7 and page 10 of their datasheet.
https://www.toshiba.com/taec/components2/Datasheet_Sync/382/27885.pdf
The excellent little Linistepper driver (which is open source and about equal in ability to the Polulus) will not work with RAMPs/Marlin either. So sad, as it would be perfect, since it’s totally open source, and really fast and smooth:
https://www.linistepper.com
The Marlin code is written in such a way that it would be very difficult to extend the pulse in software. Teacup firmware appears to make a longer pulse, but it isn’t as popular (as I understand it). One possible solution is to add a pulse stretching circuit with a cap to charge up and hold the pulse signal for a while. That is still something we might explore. But…
It turns out our new THB6064AH driver had a cap on the step pin already! And it just pulls the 1uS pulse out past the 2.3uS needed by the chip. So… the existing driver, as supplied, will work with the RAMPS/Marlin RepRap controller!
https://www.ecomorder.com/techref/ecomprice.asp?p=416074.
We now have a nice little adapter PCB to convert the Pololu board pinout to the PMinMO standard for open source stepper motor drivers, used by the THB6064AH driver kit (and others). You can watch a video about it:
We sell the little adapter cable/kit here:
https://massmind.ecomorder.com/techref/ecomprice.asp?p=416076
Remember to order one per axis.
Here is the pinout of the Polulu connector on the RAMPS board and the cable I made to the THB6064AH PMinMO connector. If you are looking down at the top of a Ultimaker v1.2 ramps board, with the power connectors on the left, and the dual row data connector on the right, JP4 of each Polulu is the lower connector in each set, numbered from RIGHT to LEFT. JP2 is the top right two pins: GND is top right, VDD is the next pin to the left. This may be different on your board, CHECK MY WORK before you go hooking things up and frying something?
RAMPS Pin. Signal – PMinMO Pin
JP4:
1. DIR – 3
2. STEP – 5
3. /SLP – n/a
4. /RST – n/a
5. MS3 – n/a
6. MS2 – n/a
7. MS1 – n/a
8. /EN – 1
JP2
1. GND – 7,2,4,6,8,10
2. VDD – 9
I made the cable from a pair of 1×6 AMPMODU headers I superglued together. It would probably be better to use a 2×6, like the TE Connectivity #925367-6 and the matching crimp terminal. I use Harwin M20-1180046. Crimp with a cheap Hanlong HT-213 crimping tool. $12 at Jameco. It’s possible to just use a pair of pliers and solder the wire on, but I like the crimp from the tool much better.
On the PMinMO side, it’s the same, but with a 2×5 housing. So I would order extra 2×6′s and just cut off one pair to make a 2×5. But a better person would buy a 2×6 AMPMODU. Nomally the PMinMO side is a 2×5 IDC but ribbon cable doesn’t work well when re-arranging the pin order.
We now have a little PCB adapter that plugs in, in place of the Polulu and accepts our standard ribbon cable for 1 driver:
https://massmind.ecomorder.com/techref/ecomprice.asp?p=416076
Remember to order one per axis.
Post time: Jun-15-2017