Wow, thanks NoobMan! Lots of good advice.
No, I did not realize that this layout would invert the gates. I took it from the Gen7 development thread. The inversion was mentioned a little later in the thread, but I must have missed it the first time through. The smaller gate is in there because the IRLB 8743's don't work well at 3.3V. How does the attached image look? I took this layout from bobc_hardware/RAMPS_FD, and it was explicitly listed as non-inverting.
Yes, I put the diode in backwards. Whoops. I just used the same one RAMPS uses, since I haven't had any issues.
I'll make all the tracks larger. I just sorta guessed on size.
I'll change the pullup resistors. I just used what RAMPS uses, I didn't do my research. As for the caps, what would they go between? VCC and ground, or something else? I've already got them between 12V and ground at each one.
More motor header space is a good idea, I didn't think that one all the way through.
I had originally laid it out with the mcu on the bottom, with female headers facing up like the Arduino. I had tried to have the pololus straddle the pins, but it didn't quite work, but my brain was stuck thinking of the Xpresso on the bottom. As I make these changes I may try laying it out with the mcu on top (pins facing down), so I'll have to move the headers and buttons out from underneath. Similarly, I found this: http://reprap.org/wiki/Sanguish]polyfuse on bottom[/url] (third picture on right-hand side). Do you see any problem with having the polyfuses under the board, tilted flat? It will make laying them out a little easier.
The schematics don't make power very obvious, but it looks like it can be done two ways: if you have 3.3V already, you can feed it straight into the VCC port (pin 28), or you can power through VIN at pin 2. One place said VIN takes 4.5V to 5.5V, and one said 4.5V to 14V, so I'm going to play it safe and power at 5V, from either USB or from main power through a transistor.
I'll add the I2C header. I'm assuming I should put the pullups on this board, right? Or will those be on the slave board?
Good point about the wiki page. I haven't ever done one, so that will be a good learning experience.
I had posted on the Smoothie forum as well, and they also mentioned the mosfet ground issue, which I hadn't known about. And yeah, that bottom left corner of the board is a bit of a mess, I think I'll re-work that so the grounds and +12V are a little nicer and cleaner and less likely to melt the board. Again, thank you a ton for all the recommendations. I think you just saved me many weeks of trial and error already.
EDIT2: Stupid broken links. Fixed.
No, I did not realize that this layout would invert the gates. I took it from the Gen7 development thread. The inversion was mentioned a little later in the thread, but I must have missed it the first time through. The smaller gate is in there because the IRLB 8743's don't work well at 3.3V. How does the attached image look? I took this layout from bobc_hardware/RAMPS_FD, and it was explicitly listed as non-inverting.
Yes, I put the diode in backwards. Whoops. I just used the same one RAMPS uses, since I haven't had any issues.
I'll make all the tracks larger. I just sorta guessed on size.
I'll change the pullup resistors. I just used what RAMPS uses, I didn't do my research. As for the caps, what would they go between? VCC and ground, or something else? I've already got them between 12V and ground at each one.
More motor header space is a good idea, I didn't think that one all the way through.
I had originally laid it out with the mcu on the bottom, with female headers facing up like the Arduino. I had tried to have the pololus straddle the pins, but it didn't quite work, but my brain was stuck thinking of the Xpresso on the bottom. As I make these changes I may try laying it out with the mcu on top (pins facing down), so I'll have to move the headers and buttons out from underneath. Similarly, I found this: http://reprap.org/wiki/Sanguish]polyfuse on bottom[/url] (third picture on right-hand side). Do you see any problem with having the polyfuses under the board, tilted flat? It will make laying them out a little easier.
The schematics don't make power very obvious, but it looks like it can be done two ways: if you have 3.3V already, you can feed it straight into the VCC port (pin 28), or you can power through VIN at pin 2. One place said VIN takes 4.5V to 5.5V, and one said 4.5V to 14V, so I'm going to play it safe and power at 5V, from either USB or from main power through a transistor.
I'll add the I2C header. I'm assuming I should put the pullups on this board, right? Or will those be on the slave board?
Good point about the wiki page. I haven't ever done one, so that will be a good learning experience.
I had posted on the Smoothie forum as well, and they also mentioned the mosfet ground issue, which I hadn't known about. And yeah, that bottom left corner of the board is a bit of a mess, I think I'll re-work that so the grounds and +12V are a little nicer and cleaner and less likely to melt the board. Again, thank you a ton for all the recommendations. I think you just saved me many weeks of trial and error already.
EDIT2: Stupid broken links. Fixed.