Added 2 additional connections for remote temperature sensors
Added weak pull up for fault pins
Q - I read up on the fault pin and the logic level is “low” if there is a fault. I found it could be weakly “pulled up” (not sure if this resets after an error?). Does pulling it up prevent it from floating to a fault state and impeding the operation of the driver chip? FYI - I’m not doing this at present on my prototypes and they seem to work.
Yes, when a motor stalls the amps go up. It would be quite surprising if the motor wasn’t internally protected to shut off in that case though. So, after a surge of high amps it should go to zero quite quickly. Ideally you want the saw on an independent circuit with appropriate breaker as a backup to this. I’m not sure what you want to final setup to be but you could have a small breaker box with the electronics in a box tied to it. You could use the knockout plugs and some conduit fittings to make it one unit.
I meant to only connect them together if you wanted to connect them to one of the Pi’s GPIO pins in order to monitor them. Ideally you would connect each to it’s own GPIO but since you seem to be running out I suggested you tie them together so you could at least detect a fault even if you can’t detect which driver caused the fault. Not need for a pull up, if you connect it to the Pi then the Pi can provide the pull up, if not then just leave them unconnected.
Your power LED is not connected. Give the zener a Dn reference id. I usually give LEDs a Dn reference as well but that’s just a personal preference.
By Dn I meant replace n with a number, ie. D1, D2 …
You have more than one zener.
Your FET circuits on your relays will not work. You’re better off using 5V. Why do you want two remote relays, you already have two free ones on the board?
The remote relays are b/c I wanted to keep the high voltage systems separate from the low voltage (the internal housings are also located in different areas of the saw). When I built my first prototype I found some interference from the AC current as well. Also makes the housings cleaner and less cluttered and fits the saw internals better.
I may be missing something but the FETS are driven by 5V from the UNL2803A and the 24V is sent to the relay coil. I wanted to avoid having a hot wire through the coil and waiting for the ground to open. I figured I could use the other side of the relay coil connected to ground as the ground. Do the FETs have to be placed as a switch opening and closing flow to ground after the laod?
The ULN2803 sinks current to ground through NPN transistors, not 5V. The FET needs a positive voltage on the gate relative to the “source”, how can your source switch 24V in that case? If you used a pull up resistor to pull the gate up to 5V and let the ULN2803 turn it off it would mean the FET would turn on every time you powered up until the Pi booted and turned them off. Not ideal. You need to use the same circuit you used for the fans and drive the gate with a Pi GPIO pin.
You still haven’t changed the ref id of the second zener or the regulator.
LED9 will not work as it is. Remember the ULN2803 provides a connection to ground.
To keep your LEDs a consistent brightness (assuming you use all the same LEDs) the current limiting resistor for LEDs powered by 5V should be 1K and the resistors for the LEDs powered by 24V should be 4K7. All LEDs will then get about 5ma.
All of your connectors have a ref id starting with J except for the Pause Button which starts with P. Not that it matters, you might have done that for a reason, if not you might want to be consistent.
A few markers on the DRC, but none that seemed more than a warning.
ERC report (5/30/2017 2:18:09 PM, Encoding UTF8 )
***** Sheet /
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (96.52 mm,43.18 mm): Pin 2 (Input) of component STP_DRV_1 is not driven (Net 5).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (96.52 mm,40.64 mm): Pin 3 (Input) of component STP_DRV_1 is not driven (Net 6).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (96.52 mm,38.10 mm): Pin 4 (Input) of component STP_DRV_1 is not driven (Net 7).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (96.52 mm,66.04 mm): Pin 4 (Input) of component STP_DRV_2 is not driven (Net 16).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (96.52 mm,68.58 mm): Pin 3 (Input) of component STP_DRV_2 is not driven (Net 17).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (96.52 mm,71.12 mm): Pin 2 (Input) of component STP_DRV_2 is not driven (Net 18).
ErrType(4): Conflict problem between pins. Severity: warning
@ (151.13 mm,64.77 mm): Pin 2 (Bidirectional) of component U2 is connected to
@ (113.03 mm,175.26 mm): pin VO (Power output) of component APXW005A0X3-SRZ1 (net 26).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (104.14 mm,93.98 mm): Pin 1 (Input) of component SW1 is not driven (Net 39).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (96.52 mm,96.52 mm): Pin 3 (Input) of component STP_DRV_3 is not driven (Net 44).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (104.14 mm,99.06 mm): Pin 3 (Input) of component SW1 is not driven (Net 45).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (257.81 mm,102.87 mm): Pin 1 (Power input) of component #PWR016 is not driven (Net 59).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (30.48 mm,66.04 mm): Pin 1 (Power input) of component #PWR039 is not driven (Net 60).
ErrType(3): Pin connected to some others pins but no pin to drive it
@ (153.67 mm,44.45 mm): Pin 3 (Power input) of component U1 is not driven (Net 71).
As I note in this post, it’s OK to continue posting about this here in the projects category, but I did want to invite you to a more general electronics forum, which might be a better fit for future posts:
