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Alden Hart's User page

This page hopefully answers some of the questions about TinyG and grblshield. If not, please post to the forum and we'll try to answer the question.

What is TinyG?

TinyG is a motor control project Riley Porter and I started about 2 years ago:

  • It's a fork from grbl. We've done a lot of work on it since. We are working closely with the grbl project to stay aligned, but there are differences
  • TinyG is a single -board solution with an integrated microcontroller (Atmel xmega) and 4 stepper drivers (TI DRV8811) capable of driving 2.5 amps per winding. The stepper drivers are VERY robust and we've never blown one out or heard of anyone else doing this, so we thought it was safe to put them on an integrated board.
  • TinyG is a 6 axis controller. It runs the linear XYZ axes, and also rotary ABC axes. These can be mapped as needed by configuration to the 4 motor drivers. You can also map an axis to 2 drivers for dual gantry operation (I think Edward has something like this up his sleeve)
  • TinyG uses a constant jerk motion planner (3rd order control) as opposed to a constant acceleration planner (2nd order control) used by grbl, EMC2, Mach3 and others. This creates S curve velocity acceleration and deceleration curves as opposed to trapezoids. This means that the machine can be run faster.

What is grblshield?

Grblshield is essentially the motor control section of TinyG, scaled down to 3 axes and put in an Arduino shield format. It uses the same driver chips and has the same specs.

  • It's designed to be compatible with grbl (hence the name!) and uses the exact same pinouts (from version 0.7 onward) so it's plug and play out of the box.

Why are the drivers not replaceable ?

Because they don't have to be. Unlike some stepper driver boards TinyG and grblshield use the TI DRV8811 stepper driver chips which are virtually indestructible. They have a good overcurrent and thermal shutdown that prevents them from blowing out. We've abused these things for 2 years and have not seen one blow yet. Nor have we heard of any of our users having a blowout.