02/20/2018 at 21:10 •
I finally took some time to solder the magnetic encoder and XLR PCBs.
Here they are :
The encoder boards has a AMS AS5132 chip, which should be capable of a 1° resolution.
It has a NEMA23 form factor and can double as a mounting support for the TMC5130 board.
I haven't had the time to test it with the TMC5130 but the encoder IC seems to work :
The yellow LED is connected to the PWM output of the encoder IC, that encodes the angular position into the duty cycle. On each turn of the motor a ramp followed by a step is clearly visible, which means that the encoder works !
I will still have to experiment with the precision, but I think that the magnet placement is not ideal : too far away from the chip (the datasheet suggests a 1~2mm distance, here it is at least at 4mm) and stuck directly on the shaft which weakens further the magnetic field.
02/06/2018 at 13:30 •
Some of the connections didn't reflow well... (look at the bottom of the image). Maybe because the board was on standoffs to preserve the bottom side components ? I've never had this happen before.
Following steps :
- hot-air rework
- de-panelization (a bit harsh on the PCBs, I will have to rework the panel connections for the future revisions)
- through hole soldering
- heat sink fixed with thermal adhesive
As expected, v1.1 boards have better thermal performances (they are 4-layer instead of 2-layer). Heat spreads into the whole PCB including the mounting holes and I was able to pull a bit more current without the TMC5130 overtemp protection kicking in.
However these new boards still can't use the max 1.68A / phase current in this configuration. I will have to test with some fans that I have laying around if the full current can be achieved.
Anyway with the recent announcement of the TMC5160 by Trinamic a higher current Farfadet with external power stage will probably join the party :)
Next steps : soldering and trying the magnetic encoder and XLR extension boards... And a lot of software and documentation work !
02/01/2018 at 16:39 •
Fresh PCBs and stencil from the factory !
We have here :
- a new version of Farfadet main board (stepper motor driver), hopefully with better thermal performances than the previous
- an extension board with XLR connectors
- an extension board with a magnetic encoder for feedback
- a transceiver board designed to fit on a Teensy, with XLR or picoBlade connectivity to the Farfadets
Testing the magnetic encoder PCB fit on NEMA17 & NEMA23 :
First time ordering with ALLPCB : the quality looks excellent and that was definitely the fastest PCB order I've ever seen (less than 1 week, shipping included, for an order with 2-layer / 4-layer boards and a stencil).