Heh, you guys are quick!
The ESTOP feature was a last minute addition I couldn't resist trying, but I did goof it up. Logic chips are quite cheap, and I quite like the idea of a hardware stop.
With a quad NAND (74HC00) and removing the pullup resistors R204, R205, etc it works to a point, but an issue I have noticed is that if there is no 3/5V power from the Due (i.e. Due powered by USB, and USB disconnected), or if Due is in reset/unprogrammed, but power on 12V, then the MOSFETs for the heaters turn on. Obviously that is not ideal.
I think your 74LS244 suggestion would be better and hopefully fix that issue. I was thinking of commoning some motor enables so that all the heater outputs are on the ESTOP.
I think the board also needs 1 or 2 small FET outputs for fans etc.
Some other known issues:
- JP101 pinout needs changing
- R101 value
- need to derive a 9-10V gate voltage for 24V operation
- some of the connector positions/layout need improving
The ESTOP feature was a last minute addition I couldn't resist trying, but I did goof it up. Logic chips are quite cheap, and I quite like the idea of a hardware stop.
With a quad NAND (74HC00) and removing the pullup resistors R204, R205, etc it works to a point, but an issue I have noticed is that if there is no 3/5V power from the Due (i.e. Due powered by USB, and USB disconnected), or if Due is in reset/unprogrammed, but power on 12V, then the MOSFETs for the heaters turn on. Obviously that is not ideal.
I think your 74LS244 suggestion would be better and hopefully fix that issue. I was thinking of commoning some motor enables so that all the heater outputs are on the ESTOP.
I think the board also needs 1 or 2 small FET outputs for fans etc.
Some other known issues:
- JP101 pinout needs changing
- R101 value
- need to derive a 9-10V gate voltage for 24V operation
- some of the connector positions/layout need improving