I am building a Mendel Prusa along with the middle school kids from our Robotics group.
We have been having some issues with the Sanguinololu v1.3 board design and have fried the 1284p in the process.
I have a board kit purchased (from Botronicz) and 'no name' pololu stepper boards from ebay. We are setting up the extruder thermistor, and dry running the printer OK until yesterday when the X-axis would not reverse direction. Upon checking the board, I found out that D21 I/O (x-dir) was 'stuck' at +5V. The stepper drivers were not blown, and work OK when switched around, but do not cure the issue with the X-direction.
I loaded and ran the 'blink' program to see if I could change the state of this pin (with no stepper drivers on the board). No luck. It seems that the pin is shorted. All other axis direction pins worked OK and could be modified by the 'blink' program.
Looking at the board design, none of the I/O pins have any type of current limiting protection. I know that the stepper boards 'should' be TTL compatible, but wouldn't it be prudent to add 470 Ohm resistors to all of the I/O lines to protect from over current issues?
Just asking,
Chris G.
We have been having some issues with the Sanguinololu v1.3 board design and have fried the 1284p in the process.
I have a board kit purchased (from Botronicz) and 'no name' pololu stepper boards from ebay. We are setting up the extruder thermistor, and dry running the printer OK until yesterday when the X-axis would not reverse direction. Upon checking the board, I found out that D21 I/O (x-dir) was 'stuck' at +5V. The stepper drivers were not blown, and work OK when switched around, but do not cure the issue with the X-direction.
I loaded and ran the 'blink' program to see if I could change the state of this pin (with no stepper drivers on the board). No luck. It seems that the pin is shorted. All other axis direction pins worked OK and could be modified by the 'blink' program.
Looking at the board design, none of the I/O pins have any type of current limiting protection. I know that the stepper boards 'should' be TTL compatible, but wouldn't it be prudent to add 470 Ohm resistors to all of the I/O lines to protect from over current issues?
Just asking,
Chris G.