I wired up the Sanguinololu board last night and things went very well. I jumpered the power enable pins on my new ATX power supply and then clipped the connector off of the 4 wire power connector and twisted the two power and two grounds wires together. These were inserted in the screw terminals on the Sanquinololu board and then I plugged in the USB cable. I got a steady green light so it looked like everything was ready to test.
I loaded up the Sprinter firmware that I had modified for my Mendel with no problems. Then I confirmed that Pronterface can connect to the board. I probably still have to do a lot of tweaking of the firmware but that can wait until I have a test print to use as a baseline.
My extruder is still disassembled from fixing the broken thermistor wire but I was able to wire it up on the bench to test it. I had been holding off on reassembling it and mounting it back on the machine until I could confirm that it was working correctly since it is a major pain in the ass to remove. I removed the 4 pin connector that came with my Botmill extruder and replaced it with two 2 pin connectors. The heater and thermistor connectors on the Sanguinololu are on opposite ends of the board so their arrangement just wouldn't work. After connecting with Pronterface the temp reported as 25C, which is about correct for my basement workshop so I went ahead and sent a command to heat up to 185C (PLA melting temp). The heater worked and the thermistor immediately began reporting the correct temps as it rose I confirmed that it heated up to the correct temperature and that it then started the regular on-off switching cycle in order to keep the temp stable. Being fairly certain that I could melt plastic safely I then moved on to the steppers.
The Sanguinololu board expects 4 pin connectors and my old boards had screw terminals so I can't hook up the steppers until I get the correct connectors. I had bought some locally only to find that I had the wrong ones. I have a set coming in the mail but they have not arrived yet. Luckily I have one stepper that arrived with the correct connector already attached so I used that one for testing. I attached it to the extruder controller and sent a command to extrude 5 mm. The stepper kicked in and ran for what seemed to be the correct time period. Hot Damn!
I then moved the motor to each of the X, Y, and Z controllers in sequence and tested them with the jog commands. All seemed to be working correctly. The only thing that I did not test was the opto-endstops. I have to solder a joint between two pads on the board in order to set the voltage for them. In my case this is 5v but I forgot to do it before I hooked everything up so it will have to wait until I take everything apart again prior to the final assembly..
So it looks like I am finally ready to print. As soon as my connectors arrive I can do the final hookups of the steppers and move on the the really interesting part of this whole thing, the printing!