Digital DRO

Note: This page and the DRO capability have not been tested since 2014, so be advised.

Using the Digital Digital Readout

The Digital Digital Read Out uses G2 on a Due to count steps of an external device and convert them back to position for display as JSON. This is useful for very fine accuracy measurement and testing.

Building the DDRO

The digital DRO builds from the digital-dro branch of the Synthetos G2 github repo. Do this:

• clone the G2 repo
• checkout the digital-dro branch
• select the SAM3X8E as the device
• compile in Atmel Studio 6 using the the DDRO configuration (pulldown window)
• flash to a Due using the Tools/Device Programming window

You should see an OpenMoko TinyG v2 USB port when flashing is finished. Connect this to a terminal emulator such as Coolterm (our favorite).

Hardware Setup

You will need a board-under-test and an Arduino Due (the DDRO). The board under test can be a TinyG v8 or v9, or any board that outputs individual step, direction, and ~enable signals for each axis. These should be 3.3v signals or you may blow up the Due. Up to 6 axes are supported.

Due pinouts are numbered as they appear on the board. Assumes motor mapping 1,2,3,4 to X,Y,Z,A

Due Pin	Signal	Description
14	GROUND
2	X step
5	X dir
22	X enable
3	Y step
6	Y dir
25	Y enable
4	Z step
7	Z dir
28	Z enable
31	A step
32	A dir
33	A enable

Software Setup

You should see an OpenMoko TinyG v2 USB port which will show up as usbmodem001 or something similar in the Coolterm Options / Serial Port dialog (did we mention Coolterm was our favorite?). You do not need to set a baud rate or flow control as these are handed by the USB on the Due. You may want to select terminal mode, CR line feed from the Terminal page

The following elements in the config must match the board under test.

Motor Configuration

1 is used as an example but all motors should be set.

Token	Element	Description / Instruction
1ma	map-to-axis	Map the motors to the same axes as the board under test
1sa	step-angle	Same as the corresponding motor on the test board
1tr	travel-per-revolution	Same as the corresponding motor on the test board
1mi	microsteps	Same as the corresponding motor on the test board
1po	polarity	Set so the steps and position go positive when the test board goes positive. Should be the same settings as on the test board, but might not be. Best to test.

Axis Configuration

X is used as an example but all axes should be set. Only the axis mode needs to be set.

Token	Element	Description / Instruction
Xam	axis-mode	Same as the corresponding axis on the test board

Sys Configuration

Token	Element	Description / Instruction
sv	status-verbosity	2=VERBOSE (recommended, not mandatory)

Use

You can use this many ways, but here's a common example

• Set the system to JSON mode by typing {
• Run the board under test and watch the streaming position and step count

To clear (zero) the counters type

{clc:n} or $clc

Remember to reset to JSON mode by typing a { if the latter.