MAY,8, 2018

Electronic Design (Group Project)

this week assignement are:

  • Design a machine (mechanism + actuation + automation), including the end effector, build the passive parts and operate it manually.

rotocasting machine


This week we decide to work on a rotomoulding machine.

The electronics part

for the electronics i decide to make our own board. for that we will connect 3 things.
  • One screen in I²C
  • One encoder + button
  • One stepper motor.
for using the screen in I²C we werent able to make it work on an attiny 44. so it was time to make our own ARDUINO LIKE.
so i based my design into the SATCHAKIT MICRO but i add a 12V regulator circuit for giving enough power to the NEMA17, i made the pinout for the A4988 and all the connection needed. add some voltage entrance, and redesign the pinout for what i need. i change everything for beeing able to made it in CMS.

EAGLE design

i started by looking what part we have in the lab. so we having 7805 in smd package. but the format of the package wasn't write on it. hopefully i received few days before: a ruler with the size of different packaging .
gain so much time, i was able to find the good library for the D2PAK aka TO 263

Milling

The milling part was the hardest.
I had to mill the QF32 ATMEGA328 with an 0.1 "V shape mill" with 20° angle. but it was to whide for beeing able to solder it. or it wasn't cutting deep enough.. the time to receive the good bit i made So much test. and was almost satisfy of the result. but i wasn't able to Reproduce the result mutliple time, for the simple reason that a pcb sheet is never perfectly flat. and with a V bit we can feel it!
the good & bad V bits Here you can see a part of many test i made:

So monday we received the good bit. and i was able to mill the board with a V shape Mill but a 10° this time. and it was perfect the first time. i was really happy of the result. and Monday night i tried to solder an ATMEGA328, in the crappy board i already made. the idea was to be able to see the result on the binocular. and learn how to solder.
After this test i learned a lot about how to solder a QFP32. so i decide make my final board. i started by soldering the 7805 Regulator Package to the board. like that i was able to see if i had the perfect 12v transform in 5 volt before making anyother mistake.
so that worked fine. so i decide to solder a Atmega328 slowly on the final board. pretty hard but doable. we ar using QFP32 0.8 package. i can't imagine soldering by hand a QFP32 0.5
I used Nail polish for protecting some part of the pcb where i some component are overlaying some path of the pcb. When that done i started to solder everything, and test the path with my multimeter! everything looked fine. so it was time to upload the programm.

Uploading some code

so for uploading the code i checked on the satshakit micro documentation in github pretty simple like an attiny44, we had to connect the isp pinout into an AVR MKII
  • 13 to 13
  • 12 to 12
  • 11 to 11
  • 10 to reset
  • 5V to VCC
  • GND to GND
when you did that you have to plug your aduino and use the sketch ISP in it. for doing that the Week 8 about is explaining all of that.
and after that we have to burn the bootlader into our board ET VOILAA! --

file of the week.

here you'll find the file of the week

For downloading
right click and save as

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