iskewb

ISkewB Industrial Servo Brick  

This will be an integrated motor module - motor, sensors, power electronics and data acquisition, all housed in a compact, rugged, waterproof heatsink/enclosure. Plug it in and go! Target budget is $40 each.. damn that makes it sound expensive It actually is turning out to be quite a challenge to get it that low.. Will need six of these for each hextatic.

The first version will use an atmega48 to PWM a DIY h-bridge and simultaneously count encoder pulses, talk SPI via cat5 cable with a motherchip, and read/write i/o for limit switches and whatever else. (thermistor? cooling fans?) I might have trouble reading encoder signals at high speeds while juggling all the other code, and so i may end up using an attiny13 for the sole purpose of decoding and counting quadrature pulses. Not a big deal at $0.54 each; the deciding factor will be whether it complicates or simplifies the overall design, including software.

RJ45 interface pinout  

5V
GND
SS
SCK
MISO
MOSI
Fault (open collector-ish)

Parts list:  

h-bridge

power stage

127K9720

servo motor

pcb mount RJ45 jack

top entry Jameco P/N 524488 $0.39 each min qty 10
OR

• pcb mount RJ45 jack side entry low profile Jameco P/N 524461 $0.55 ea min qty 10
  OR
• ES1607 shielded PCB mount RJ45 jack from excesssolutions.com $0.25 each min qty ??

cable assembly,cat 5e,3ft

jameco p/n 523021, $1.33 ea min qty 2

Standard Opto-interrupter, fork style, qty 2

- forhome and index pulse goldmine-elec.com p/n GP44, $0.14 ea min qty 18 (or so) (i know bad choice of components, i'll find something on jameco or digikey later, something like Jameco P/N 114091)

thermistor

goldmine-elec.com p/n G14610, $0.33 ea, min qty 3

encoder read board:  

attiny13

cheap powerful microcontroller to read encoder signals and index pulse

atmega48

PWM the h-bridge, monitor motor current, temperature, i/o and whatever else.

CAP,RADIAL,33uF,50V, 5mm x 11mm

power filter for attiny13, Jameco p/n 93745PS, $0.05 ea min qty 10

CAP,CERM,DISC,.1uF,50V

power filter for attiny13, Jameco p/n 15270, $0.15 ea min qty 10

cd-rom audio connector

for connecting the encoder lines, maybe this should go in iskewb..Jameco P/N 100802CK $0.25 min qty 10, and jameco p/n 152733CK (maybe?) $0.45 (need pins too) jameco p/n 181673 another $0.44 each. also maybe molex 50-57-9004 would work, it can be obtained from digikey.