alden

The 2 oz copper on the board and the exposed pads are the heatsink. This (and a fan) is all we need to cool everything TinyG can run. I’ve been using the 2.8 amp Kelings (Automation Technology) that I think you mention.

We used to ship TinyG with the little heatsinks (technically “heat spreaders”) that you probably recall. We removed the heatsinks because we discovered that using a fan to cool the bottom of the board was much more effective. The heat comes from the bottom of the chip, and the chip bottom is soldered via a “power pad” to the top copper and from there to the bottom copper through a bunch of thermal vias.

The other thing we found that was on a few occasions people had managed to blow out their boards because the heatsinks slipped off the chip and contacted the leads. We replaced the boards, but now we don’t like to see heatsinks on the top of the board, and don’t recommend them.

We played with some big heatsinks as you can see here:

If you really wanted to heatsink the board I’d recommend some double sided thermally conductive / electrically insulating tape (see digikey or mouser) and a Duron or some other big CPU heatsink. But I have not needed this.

I should add that once these motors broke in a bit the rumble at the low end was not nearly as noticeable. It was also never a problem. I really like these motors and they work great with TinyG.

• This reply was modified 11 years ago by alden.

We don;t have a diagram, but wiring the switches should be pretty straightforward. If all you want are homing switches (no limits) then you need 3 switches:

– X minimum travel – on the left-hand side of the machine by convention
– Y minimum travel – at the front of the machine by convention
– Z maximum travel – at the top of Z travel by convention

Then just wire the 2 wires to ground and Xmin, ground and Ymin, and ground and Zmax, respectively. It’s better to use the normally closed settings (NC). Set the $ST setting accordingly.

I’d start there and get it working, then try the limits if you want them.

Be advised, switches and switch wiring can pick up noise and fire erratically – particularly if you have a noisy spindle. Best to use twisted pair shielded wire, and attach the shield to ground at the tinyg side.

I’m writing something up on the wiki to help with your inquiry. There are enough people working on programmatic interfaces that this needs some attention. Please give me a day or 2 to get this in place and I’ll post a follow up.

• This reply was modified 11 years ago by alden.

Slight correction. XON/XOFF ($ex=1) will work as the protocol is run entirely from the tinyg firmware and does not involve the FTDI. The The FTDI passes XON and XOFF characters through as it does any other serial character. Obviously the host needs to know handle XON/XOFF for this to be effective.

RTS/CTS ($ex=2) does involve the FTDI. The RTS and CTS signals are connected to the xmega pins, and the FTDI acts as a “translator” performing the USB flow control corresponding to the RTS/CTS transitions.

So in bypassing the FTDI by using the RX/TX directly XON/XOFF is available, whereas RTS/CTS is not.

In your $$ dump flow control is set to Xon/Xoff. Is your host observing this? I don’t think RTS/CTS ($ex=2) is an option as the RX/TX/GND/3.3 wifi connection bypasses the FTDI USB chip, which emulates the RTS/CTS signals over USB.

Can you provide information about the motor and where you got it? Did you only get one?

You are correct about the latch backoff. It’s just a maximum travel for the latch phase. It’s also used if any switches are tripped during startup to back off those switches before starting the search. It’s really in there as a failsafe so that if the switch transition was not detected the machine would stop on its own.

I suspect the reason the head gets to the latch backoff distance at high speed is that the jerk needs some time to slow down. The deceleration should be actually starting when the switch transition occurs. Please let me know if you see evidence to the contrary – that would be a bug. The latch phase is designed to run slowly so you get an accurate and repeatable stop.

The zero backoff is optional, but you should try a rapid return to zero and see if your limits trip. If they do you need to add some backoff as a buffer.