The microcontroller I choose is the ATtiny85. With few tweaks it fits perfectly with me needs. The LED ring is not a must, but it can add some nice effects when I turn the dial or press the button. The encoder is the obvious choice for detecting the direction of the wheel and also to counts steps. To use the Digispark board from the areduino IDE, I needed to add it with its libraries to the Arduino board manager. TL;DR<\/strong> – Board Manager URL:<\/span>\u00a0 \u00a0 http:\/\/digistump.com\/package_digistump_index.json<\/p>\n I also need to make few tweaks to the board as I mentions earlier:<\/p>\n To change the fuse, I used USBASP V2.0 I had laying around. PB0 – MOSI Then I used ‘avrdude’ to check if everything is connected and responding, and the current I got this respond:<\/p>\n Everything is good.<\/p>\n I entered the fuse values in this calculator:\u00a0 http:\/\/www.engbedded.com\/fusecalc\/<\/a> Only the HIGH fuse changed, so I only change it with this command: (hfuse – HIGH, w – WRITE, 0x5F – Fuse Value, m Program )<\/p>\n and this is the respond:<\/p>\n Perfect.<\/p>\n Now for the LED, I just remove the resistor connected to PB1. The design I made (using Fusion 360) contains 3 main parts:<\/p>\n I printed all the parts in a black PLA, and the top transparent ring in a clear PLA. First I assembled the top part. I inserted the transparent ring to the top part body (and added few drops of glue), Then I solders 3 wires to the led ring where is says\u00a0 V+, IN and G, I also solders wires to all the encoders legs and fixed it to the center part as well.<\/p>\n I used the ATtiny internal pullups for the encoder A and B, and also for the button so no external pullups resistors are needed.<\/p>\n Now I connected the Digispark board to the bottom part with two 3mm M3 screws, and connected the middle part to the bottom part with two long M3 screw.<\/p>\n At the bottom part, I room for 8mm anti-slip stickers, but it’s not a must.<\/p>\n![\"\"](\"http:\/\/itay.mobi\/blog\/wp-content\/uploads\/2018\/03\/DSC_5531.jpg\")
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\nI bought a Digispark clone board. It is very small and has a micro usb connector which connects to pins PB3 and PB4 of the ATtiny .
\nThis board is able to emulate HID device with the Digispark libraries.<\/p>\n
\nThe WS2812 is an addressable led, so we only need 1 gpio from the ATtiny to control all the 16 leds.
\nDigispark provides a version of the Adafruit Nexopixel library to the Digispark boards.<\/p>\n
\nIt also has a button and I can add more features with a button click or double clicks.<\/p>\nModifying the Digispark<\/h2>\n
\nHere is a quick guide from their website:
\nhttps:\/\/digistump.com\/wiki\/digispark\/tutorials\/connecting<\/a><\/p>\n\n
\nThis is how I connected the IO to the USBASP:<\/p>\n
\nPB1 – MISO
\nPB2 – SCK
\nPB5 – RESET
\nVCC to 5V, and of course the grounds.<\/p>\n
\nfuse settings with the command: (the path might be different in other systems)<\/p>\nC:\\Program Files (x86)\\Arduino\\hardware\\tools\\avr\\bin>avrdude.exe -C \"C:\\Program Files (x86)\\Arduino\\hardware\\tools\\avr\/etc\/avrdude.conf\" -c usbasp -p attiny85 -n\n<\/pre>\n
avrdude.exe: warning: cannot set sck period. please check for usbasp firmware update.\navrdude.exe: AVR device initialized and ready to accept instructions\n\nReading | ################################################## | 100% 0.03s\n\navrdude.exe: Device signature = 0x1e930b (probably t85)\n\navrdude.exe: safemode: Fuses OK (E:FE, H:DD, L:E1)\n\navrdude.exe done. Thank you.<\/pre>\n
\nand checked the ‘RSTDISBL’ (external reset disabled) to get the new fuse values.<\/p>\nC:\\Program Files (x86)\\Arduino\\hardware\\tools\\avr\\bin>avrdude.exe -C \"C:\\Program Files (x86)\\Arduino\\hardware\\tools\\avr\/etc\/avrdude.conf\" -c usbasp -p attiny85 -U hfuse:w:0x5F:m<\/pre>\n
avrdude.exe: warning: cannot set sck period. please check for usbasp firmware update.\navrdude.exe: AVR device initialized and ready to accept instructions\n\nReading | ################################################## | 100% 0.03s\n\navrdude.exe: Device signature = 0x1e930b (probably t85)\navrdude.exe: reading input file \"0x5F\"\navrdude.exe: writing hfuse (1 bytes):\n\nWriting | ################################################## | 100% 0.02s\n\navrdude.exe: 1 bytes of hfuse written\navrdude.exe: verifying hfuse memory against 0x5F:\navrdude.exe: load data hfuse data from input file 0x5F:\navrdude.exe: input file 0x5F contains 1 bytes\navrdude.exe: reading on-chip hfuse data:\n\nReading | ################################################## | 100% 0.01s\n\navrdude.exe: verifying ...\navrdude.exe: 1 bytes of hfuse verified\n\navrdude.exe: safemode: Fuses OK (E:FE, H:5F, L:E1)\n\navrdude.exe done. Thank you.<\/pre>\n
\nIt’s the small resistor between the ATtiny85 and the voltage regulator.
\n<\/a><\/p>\nDesigning and Printing<\/h2>\n
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\na transparent ring for viewing the leds.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/a><\/p>\n
\nAfter few hours in my 3D printer (I used the CR-10 Mini), this is what came up:<\/p>\n<\/a><\/p>\nAssembling<\/h2>\n
\nand then did the same thing with the center part.<\/p>\n<\/a><\/p>\n
\nand\u00a0I passed them through the holes in the middle parts.<\/p>\n<\/a>Now I solders the wires to the Digispark board as the following scheme:<\/a><\/p>\n<\/a> <\/a><\/p>\nCode<\/h2>\n