Notifications
Clear all

FabScanPi HAT and A4988 Driver


agressor
Posts: 3
Topic starter
(@agressor)
Active Member
Joined: 3 years ago

Hi,

 

got the FabScanPi Hat and the wooden frame about a year ago. The basic setup was easy enough but the "advertised" use of the old a4988 drivers posed a bigger set of problems. [i have a lot of the older drivers laying around and wanted to use those for this piece of kit]

After about a week of troubleshooting without any movement of the steppermotor including the use an oscilloscope and bitsniffer my frustrated indexfinger found the solution accidentaly. While hotswaping the driver the motor suddenly sprang to life...

For the A4988 to work the Reset and Sleeppin have to be connected. The HAT itselfe does'nt provide this so you have to solder this bridge yourself.

For the DRV8825 [another one of the olds] needs a connection of Reset and Sleep to VCC [also DIY soldering]

The fancy stepsticks [TMC####] do not seem to need those connected to anything.

 

I have not fornd any mention of this in the documentation. hopefully you can use this information for your Fabscan with the older hardwarebits

Reply
4 Replies
mario
Posts: 570
Admin
(@mario)
Member
Joined: 4 years ago
Posted by: @agressor

For the A4988 to work the Reset and Sleeppin have to be connected. The HAT itselfe does'nt provide this so you have to solder this bridge yourself.

Thank you for reporting! I will add this to the documentation. But i think there is one more thing. You need to set micro stepping for those drivers. The TMC drivers are 1/16 by default. The HAT does not configure the pins MS1 - MS3 for a A4988 by default. The solder pads on the HAT are open. You need to bridge the pads for setting the driver to 1/16 step.

Bildschirmfoto 2020 01 09 um 09.22.46 (3)

 

Reply
agressor
(@agressor)
Joined: 3 years ago

Active Member
Posts: 3

@mario

ah, good tip. 
haven't gotten that far yet, was just glad that the motor was moving at all

 

Cheers

Reply
archeotron
Posts: 17
(@archeotron)
Active Member
Joined: 3 years ago

Hello,

should there all three soldered, like this????

158 Bildschirmfoto 2020 01 09 um 09 22 46 3

 

Reply
mario
Posts: 570
Admin
(@mario)
Member
Joined: 4 years ago
Reply
Share: