Riley

If you want to motors to turn do this.

If you are on windows find a serial port program. I found termite:
http://www.compuphase.com/software_termite.htm

Its pretty nice little program. Anyways when you plug in your arduino you need to find the port that it shows up as. Once that you settings need to be 8N1 9600 baud.

Then you basically have a serial port connection to grbl. At this point you just type in gcode commands. Like:

Grbl 0.6b
‘$’ to dump current settings
g0x05y05z05 <—-This is what I typed in. Then motors move 🙂
ok <—- Grbl’s response.

You can also do $

$
$0 = 755.906 (steps/mm x)
$1 = 755.906 (steps/mm y)
$2 = 755.906 (steps/mm z)
$3 = 30 (microseconds step pulse)
$4 = 500.0 (mm/min default feed rate)
$5 = 500.0 (mm/min default seek rate)
$6 = 0.100 (mm/arc segment)
$7 = 28 (step port invert mask. binary = 11100)
$8 = 50.0 (acceleration in mm/sec^2)
$9 = 300.0 (max instant cornering speed change in delta mm/min)
‘$x=value’ to set parameter or just ‘$’ to dump current settings
ok

To get a list of all the current settings.

Turn your current pots all the way down. (counter clockwise) then issue a command like this:

g0x1000y1000z1000

Thats a long command. Then slowly adjust the current pots. Once they start to move go a bit more then you are good to go. Just make sure you are not using too beefy of a motor without a heat sink or a fan on the chip. It will go into thermal shutdown if you don’t.

Riley

AHA! Very cool… I got home from work today and tried it out on my Macbook. Of course I still used my avrispmkII vs. your TinyISP. However it worked with avrdude today:

ril3ys-MacBook-Pro:~$ avrdude -c avrispmkII -P usb -p atmega328p -U flash:w:Downloads/grbl_0_6b_atmega328p_16mhz_9600_with_grblshield_patch.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed
To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file “Downloads/grbl_0_6b_atmega328p_16mhz_9600_with_grblshield_patch.hex”
avrdude: input file Downloads/grbl_0_6b_atmega328p_16mhz_9600_with_grblshield_patch.hex auto detected as Intel Hex
avrdude: writing flash (17418 bytes):
Writing | ################################################## | 100% 5.41s
avrdude: 17418 bytes of flash written
avrdude: verifying flash memory against Downloads/grbl_0_6b_atmega328p_16mhz_9600_with_grblshield_patch.hex:
avrdude: load data flash data from input file Downloads/grbl_0_6b_atmega328p_16mhz_9600_with_grblshield_patch.hex:
avrdude: input file Downloads/grbl_0_6b_atmega328p_16mhz_9600_with_grblshield_patch.hex auto detected as Intel Hex
avrdude: input file Downloads/grbl_0_6b_atmega328p_16mhz_9600_with_grblshield_patch.hex contains 17418 bytes
avrdude: reading on-chip flash data:
Reading | ################################################## | 100% 4.99s
avrdude: verifying …
avrdude: 17418 bytes of flash verified
avrdude: safemode: Fuses OK
avrdude done. Thank you.
ril3ys-MacBook-Pro:~$

If you are on OSX the AVR Mac Pack is a beautiful thing! Its a complete compiled toolchain for AVR. I installed that updated my path and I was good to go. I say this just an FYI for others.

Riley

Thanks for the heads up on this chip – we’ve been watching the developments at TI. The 8825 is the next generation for the 8811 – same current capacity, but has some new features. TI is not in production on this chip yet, and we like to wait until it’s stable and has good supply.

Thanks,

Riley