Programmed...Finally

After about a weekend of frustrating software woes, I was finally able to get avrdude to recognize the Atmega644(v) using serjtag's AVR FTDI Bit-Banger. I was getting constant and frustrating "initialization failed rc=-1" which means the software can talk to the programmer but not the chip. I had convinced myself that the wiring was perfect and there was something wrong with the chip (even though it was a birds nest of wiring).

Test 1: Chip:
I checked the signals with an oscilloscope, the signals looked to be transmitting although I have a analog oscilloscope so I don't know how that worked out...

Test 2: Board traces:
I ruled the chip out and inspected the board traces and checked them with a multimeter, but they all turned out fine.

I finally decided to make a new cable that was a LOT cleaner looking and way better to use and tried to program it once more, yet again "initialization failed rc=-1". So I decided to try to connect to a attiny13 on a breadboard and what do you know... it works!!!

So now that I knew that the programmer worked I took the Atmega644 of the Sanguino board and tried it on the breadboard and that worked too!!! Long story short I mixed up the rows and the programming cable so row 1 would connect to row 2 but its fixed now! Heres the new programming cable:

You may also note that the 16mhz crystal is gone on the Sanguino, I ripped it of thinking it was causing all my problems...it wasn't. Another order was sent out for 5 16mhz crystals off of eBay, more time spent waiting...

But on a side note I got my 24v psu in the mail!

Modified 2.3 Stepper Drivers 24v

I though that I might expand a little bit on the stepper drivers and the things that I did to modify them. First I changed the R5 and R8 resistors to 2.2k from 1k as to not fry the LEDs when I start to pulse the ABCD stepper channels. I also changed the sense resistor from a .25 ohm resistor to a .5 ohm resistor, I don't know if this was needed or if it was necessary, we will find out in the testing. Another thing that I made sure to do was to make all of the capacitors have a 50v rating (the reason that I used a through hole capacitor instead of a SMD cap) so they won't explode on me! Also if anybody knows if the sense resistors are required to be changed or if they are supposed to stay at .25 ohms then let me know

I will be testing the board and seeing if they work and doing another blog post after that so stay tuned!

Orders received!

I received my order from newark today that included the needed capacitors and LEDs as well as some extra IDC connectors and headers. I also got the molex kits that I ordered only to realize that I only needed one but I got 3 kits, so now I have 6 extra 4 pin receptacles lying around... Along with my Newark that I received today I also got a 40 pin .05" IDC cable for making the connections between the motherboard and the stepper motor drivers. The 24v PSU is in the mail and once it arrives I am ready to test!

These boards are 95% complete all I need to do is fix the trace problem on two of the boards and test them all *fingers crossed*.

Some keen eyed people may notice that I don't have the SMT 100uf capacitors that are usually on the board, well Newark didnt't have them in stock for some reason so I just decided to use through hole capacitors with trimmed leads, and it worked perfectly! I would also like to mention that these boards are modified to run off of 24v instead of the usual 12v that Reprap boards are meant for because the motors that I am looking at run off of 24v.

Here is another picture of the comparison between a populated and unpopulated board.

On the todo list:

- Burn the bootloader on the Sanguino 

- Put the Reprap software on the sanguino

- Test the stepper motor board

- Get the stepper motors

- Run some test G-code on the sanguino and hope it moves the motors accordingly

Starting The 3D Printer

To begin this first post in ages I would like to say that I am building a Wolfstrap (a Repstrap) and have ordered a Sanguino for the motherboard as well as a programmer for it. I have also ordered/received 4 RepRap stepper boards for $2 per board but they had a silkscreen and minor trace issue. I ordered all the parts from Newark and started making the boards only to realize that I didn't have enough 100nf capacitors or enough green LEDs! So I ordered some more capacitors and LEDs and a molex connector for simple stepper motor connection witch turned out to be $18, $5 for shipping! I have also ordered some misc. things such as a power supply and a  ribbon cable for the IDC cable once I assemble and test the electronics I will start to order the mechanics of the repstrap, hopefully I will post more often!