MakerBot Replicator 1 Adapting A4988 Replacement Driver - Revision history

Ivc: /* Calcualting current */

2017-02-14T17:46:42Z

Calcualting current

← Older revision		Revision as of 17:46, 14 February 2017
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	# Done, insert into the Mightyboard with the DIR and GND pins facing the stepper motor connector		# Done, insert into the Mightyboard with the DIR and GND pins facing the stepper motor connector

	=== ~~Calcualting~~ current ===		=== Calculating current ===

	To check, the Imax will be:		To check, the Imax will be:

Ivc: /* Adjusting trimpot current limit */

2017-02-14T17:45:58Z

Adjusting trimpot current limit

← Older revision		Revision as of 17:45, 14 February 2017
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	# Use the multimeter to measure the resistance between ground and the top of the trimpot, adjust the screw until it matches the calculated value		# Use the multimeter to measure the resistance between ground and the top of the trimpot, adjust the screw until it matches the calculated value
	# Done, insert into the Mightyboard with the DIR and GND pins facing the stepper motor connector		# Done, insert into the Mightyboard with the DIR and GND pins facing the stepper motor connector

			=== Calcualting current ===

	To check, the Imax will be:		To check, the Imax will be:

Ivc: /* Adjusting trimpot current limit */

2017-02-14T17:45:33Z

Adjusting trimpot current limit

← Older revision		Revision as of 17:45, 14 February 2017
Line 55:		Line 55:
	# Use the multimeter to measure the resistance between ground and the top of the trimpot, adjust the screw until it matches the calculated value		# Use the multimeter to measure the resistance between ground and the top of the trimpot, adjust the screw until it matches the calculated value
	# Done, insert into the Mightyboard with the DIR and GND pins facing the stepper motor connector		# Done, insert into the Mightyboard with the DIR and GND pins facing the stepper motor connector

			To check, the Imax will be:

			Imax = Vref/(8 x Rsense)

			And using Vref 1.33V and 0.2Ohm:

			Imax = 1.33/(8 x 0.27) = 0.831A (831mA)

			The A4982 and A4988 can handle approx. 1A without any heatsink or active cooling, and up to 2A with cooling.

Ivc: /* Digipot values */

2017-02-14T16:57:56Z

Digipot values

← Older revision		Revision as of 16:57, 14 February 2017
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	Where 0..5k is adjusted in steps via software (MakerWafe prefs) between 0 to 127 (7-bit)		Where 0..5k is adjusted in steps via software (MakerWafe prefs) between 0 to 127 (7-bit)

			For example, N is set to 118:

			Vref = 5V(5k(118/127)/(10k+(5k*(118/127)))) = 1.59V

	== Adapting A4988 boards ==		== Adapting A4988 boards ==

Ivc: /* Digipot values */

2017-02-14T16:56:06Z

Digipot values

← Older revision		Revision as of 16:56, 14 February 2017
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	The Vref is adjusted by changing the lower-side of a voltage divider.		The Vref is adjusted by changing the lower-side of a voltage divider.

	Vref = 5V*(0..5k/(10k+0..5k)) ~~- where~~ 0..5k is adjusted in steps via software (MakerWafe prefs) between 0 to 127 (7-bit)		Vref = 5V*(0..5k/(10k+0..5k))

			Where 0..5k is adjusted in steps via software (MakerWafe prefs) between 0 to 127 (7-bit)

	== Adapting A4988 boards ==		== Adapting A4988 boards ==

Ivc at 16:55, 14 February 2017

2017-02-14T16:55:44Z

← Older revision		Revision as of 16:55, 14 February 2017
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	* A4982 boards has a better thermal design with exposed copper surface		* A4982 boards has a better thermal design with exposed copper surface
	* All A4988 board set the current limit by turning a trimpot, while A4982 on MakerBot is done digitally		* All A4988 board set the current limit by turning a trimpot, while A4982 on MakerBot is done digitally

			== Digipot values ==

			The Vref is adjusted by changing the lower-side of a voltage divider.

			Vref = 5V*(0..5k/(10k+0..5k)) - where 0..5k is adjusted in steps via software (MakerWafe prefs) between 0 to 127 (7-bit)

	== Adapting A4988 boards ==		== Adapting A4988 boards ==

Ivc: /* Adapting A4988 boards */

2017-02-14T16:45:34Z

Adapting A4988 boards

← Older revision		Revision as of 16:45, 14 February 2017
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	=== Adjusting trimpot current limit ===		=== Adjusting trimpot current limit ===

	# Check what the Rsense resistor value is on the board (or schematic), usually either 0.27/0.2/0.05 Ohms - the MakerBot sets the current limit to 830mA (0.830A)		# Check what the Rsense resistor value is on the board (or schematic), usually either 0.27/0.2/0.05 Ohms - the MakerBot sets the current limit to 830mA (0.830A) and driven by 24V for good amount of torque.
	# Find the Vref you need using this equation Vref=(8Rsense)0.830, for instance 0.2 Ohm gives (80.2)0.833=1.33V		# Find the Vref you need using this equation Vref=(8Rsense)0.830, for instance 0.2 Ohm gives (80.2)0.833=1.33V
	# Use a multimeter to measure the total resistance of the trimpot between the pads opposite of the third pad, Rpot		# Use a multimeter to measure the total resistance of the trimpot between the pads opposite of the third pad, Rpot

Ivc at 16:41, 14 February 2017

2017-02-14T16:41:42Z

← Older revision		Revision as of 16:41, 14 February 2017
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	[[Image:MakerBot Replicator digipot schematic.png\|400px\|right\|thumb\|~~Digipot~~ provides Vref]]		[[Image:MakerBot Replicator digipot schematic.png\|400px\|right\|thumb\|MCP4018T-502E/LT 7-bit 5K Digital Potentiometer provides Vref for each stepper]]
	[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]		[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]
	[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]		[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]

Ivc at 16:37, 14 February 2017

2017-02-14T16:37:21Z

← Older revision		Revision as of 16:37, 14 February 2017
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			[[Image:MakerBot Replicator digipot schematic.png\|400px\|right\|thumb\|Digipot provides Vref]]
	[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]		[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]
	[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]		[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]

Ivc at 16:32, 14 February 2017

2017-02-14T16:32:33Z

← Older revision		Revision as of 16:32, 14 February 2017
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	[[Image:MakerBot Replicator HoekDrive17 A4982 schematic.png\|400px\|right\|thumb\|HoekDrive17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]		[[Image:MakerBot Replicator HoekDrive17 A4982 schematic.png\|400px\|right\|thumb\|HoekDrive17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]
	The BotStep17 driver board on the MakerBot Replicator 1 (and 2/2X) uses the A4982 stepper drive IC. It is hard to get replacement driver boards for this model. An popular alternative which is used by many other 3D printers is the A4988. It can be adapted to work with the MakerBot 3D printers.		The BotStep17 driver board on the MakerBot Replicator 1 (and 2/2X) uses the A4982 stepper drive IC. It is hard to get replacement driver boards for this model. An popular alternative which is used by many other 3D printers is the A4988. It can be adapted to work with the MakerBot 3D printers.

			* [https://www.pololu.com/file/download/a4988_DMOS_microstepping_driver_with_translator.pdf?file_id=0J450 A4988 datasheet]
			* [http://www.allegromicro.com/~/media/Files/Datasheets/A4982-Datasheet.ashx A4982 datasheet]

	== Differences ==		== Differences ==

← Older revision		Revision as of 16:41, 14 February 2017
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	[[Image:MakerBot Replicator digipot schematic.png\|400px\|right\|thumb\|~~Digipot~~ provides Vref]]		[[Image:MakerBot Replicator digipot schematic.png\|400px\|right\|thumb\|MCP4018T-502E/LT 7-bit 5K Digital Potentiometer provides Vref for each stepper]]
	[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]		[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]
	[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]		[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]

← Older revision		Revision as of 16:37, 14 February 2017
Line 1:		Line 1:
			[[Image:MakerBot Replicator digipot schematic.png\|400px\|right\|thumb\|Digipot provides Vref]]
	[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]		[[Image:MakerBot Replicator BotStep17 schematic.png\|400px\|right\|thumb\|BotStep17 A4982, Rsense 0.27 Ohm, Vref set via digipot]]
	[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]		[[Image:MakerBot Replicator Polulu A4988 schematic.png\|400px\|right\|thumb\|Polulu A4988, Rsense 0.05 Ohm, Rpot 10k]]