Thanks for all the feedback. This is exactly what I was hoping for from the beta testing.
As shipped, the microstep settings are X = 1/16, Y = 1/16, Z = 1/2, and E = 1/8
Board cleanup, silkscreen, indicator LED's and reset cap are all on the to-do list for 1.0.
Mounting holes were lost during the push to shrink to under 10x10 cm for the cheap board house pricing. With a bit more arranging it should be possible to put them back.
I'm not sure I trust the 4W minifit connector for high current supply as in HBP and Hot end power. I have burned out a minifit connector on my makerbot with a much smaller heated bed. I know on Gen7 it is recommended to bypass that connector when using a heated bed.
I'll have to look at putting in a USB-serial chip on board.
Current limit is set by the current sense resistors which need to be pretty beefy so it's very hard to find a pot that is 1. low resistance (0-1 Ohm) , 2. handles the power, and 3. is affordable. With pololu's, current limit is set through a reference voltage so a small pot is fine.
Torque jumpers are for setting current lower than the max limit from the current limiting resistors. You can get 100%, 75%, 50%, and 20% of the max current through the torque jumper settings.
I haven't had any issues with the heated bed. It worked fine as is, but the traces got a bit warmer than I like so I reinforced them. That will be fixed in 1.0 by using the space better to add copper on both sides.
Enable line: It seems to me that active high logic (as it currently works) would be safer than active low. It is a bit of a pain to invert from the original active low on some firmware but I've had problems with ATX supplies getting turned on at inappropriate times (ie. board power is from USB and computer is turned off so ATX comes on.) With active high logic at least you know the ATmega must be powered on before the stepper power relay can be switched.
As shipped, the microstep settings are X = 1/16, Y = 1/16, Z = 1/2, and E = 1/8
Board cleanup, silkscreen, indicator LED's and reset cap are all on the to-do list for 1.0.
Mounting holes were lost during the push to shrink to under 10x10 cm for the cheap board house pricing. With a bit more arranging it should be possible to put them back.
I'm not sure I trust the 4W minifit connector for high current supply as in HBP and Hot end power. I have burned out a minifit connector on my makerbot with a much smaller heated bed. I know on Gen7 it is recommended to bypass that connector when using a heated bed.
I'll have to look at putting in a USB-serial chip on board.
Current limit is set by the current sense resistors which need to be pretty beefy so it's very hard to find a pot that is 1. low resistance (0-1 Ohm) , 2. handles the power, and 3. is affordable. With pololu's, current limit is set through a reference voltage so a small pot is fine.
Torque jumpers are for setting current lower than the max limit from the current limiting resistors. You can get 100%, 75%, 50%, and 20% of the max current through the torque jumper settings.
I haven't had any issues with the heated bed. It worked fine as is, but the traces got a bit warmer than I like so I reinforced them. That will be fixed in 1.0 by using the space better to add copper on both sides.
Enable line: It seems to me that active high logic (as it currently works) would be safer than active low. It is a bit of a pain to invert from the original active low on some firmware but I've had problems with ATX supplies getting turned on at inappropriate times (ie. board power is from USB and computer is turned off so ATX comes on.) With active high logic at least you know the ATmega must be powered on before the stepper power relay can be switched.