check in assembly notes

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+# BOM
+
+1x ATtiny4-TS
+1x 0806 100kΩ resistor
+1x 0806 200Ω resistor
+1x 0806 100nF capacitor
+1x CR927 lithium cell
+1x RCA/cinch style jack; 10mm inner diameter
+1x random paper staple
+
+<!--
+AliExpress search term:
+- "Luxury Soldering RCA Plug Jack Connector Speaker Audio"
+Example Listings:
+- https://www.aliexpress.com/item/33034854833.html
+- https://www.aliexpress.com/item/4000878449744.html
+- https://www.aliexpress.com/item/4000908254836.html
+Possible actual manufacturer:
+- https://www.xinwotong.com/
+- https://xinwotong.en.alibaba.com/
+-->
+
+# Tools
+
+- AVR programmer (e.g. [USBasp](https://fischl.de/usbasp/))
+- ZIF SOT23-6 socket
+- Soldering equipment
+- Side cutters
+- Kapton Tape
+- Abrasive paper, ~200 grit XXX/TODO: welche körnung?
+
+# Software
+
+`avr-gcc`, `avr-size` (optional), `avrdude`, `make`
+
+# Assembly Instructions
+
+1.  Insert MCU in ZIF socket and flash it using `make flash`.  
+    Note: the MCU requires 5V VCC for flashing!  
+    Note: to flash e.g. an ATtiny9, append `CHIP=9` to the command.
+2.  With the chip still in the socket and powered through the programmer, switch
+    the supply voltage to 3v3 and attach an oscilloscope to the DEBUG pin.
+3.  Measure the frequency of the DEBUG signal and adjust the `CAL_MAGIC` value
+    until it reads 8kHz.
+4.  Solder all components to the (flat) flex PCB.
+5.  Insulate the barrel/jacket side of the battery with a thin strip of kapton
+    tape.
+6.  Bend the staple into a U-shaped clip.  
+    The clip shall be slid over the GND via between the MCU and C1.  
+    a) roll over on one end  
+    b) ca. 7mm down, bend 95°  
+    c) ca. 2.75mm down, bend another 95°  
+    d) flare open the ends and test/adjust fitment on PCB and battery  
+    e) cut off extra length on other end and roll it over  
+    f) place a kapton tape flag over the arm that sits on the component side  
+7.  Twist together 8 strands of .1mm² enameled copper wire and cut off two ca.
+    15mm pieces. Solder onto the PCB pads.
+8.  Cut down ground clip of the RCA jack; sand off both terminals until they are
+    about 1.5mm proud off the surface.
+9.  Solder PCB to RCA jack; insulate component side with kapton tape.
+10. Push assembly text-side first deep into RCA jack housing. Test for shorts.
+11. Counter-rotate the RCA jack halfs about 3 times. This makes the wires
+    untwist when screwing the halfs together.
+12. Fully close the RCA jack. Should take about 3.5 turns. Test for shorts and
+    severing of the wires.