Project: step-up converter

I have decided to add various projects using Tinyboard directly
to this repository. The first project is a step-up converter
with current feedback for a string of LEDs.

The firmware is a dumbed-down version of firmware for my other
project: http://www.fi.muni.cz/~kas/bike-lights/, modified
for ATtiny45.

diff --git a/projects/step-up/README b/projects/step-up/README
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+Step-up converter with current feedback measurement.
+
+CPU: ATtiny45
+Driven by PWM output OC1B (PB4 pin) with MOSFET.
+Current feedback measured at ADC3 (PB3 pin).
+Output on the PB4 header (pin 1 is negative, pin 2 is positive side).
+
+
+Bill of materials:
+
+C1,C2  1.5uF tantalum
+C3,C51 10uF ceramic
+D50    SS24 Schottky diode (SMB package, 40V, 2A)
+L50    470uH, 390mA, 200 mil pin distance (probably too big for 20mA LEDs :-)
+PB4    two-pin header soldered to pins 1 and 2 of PB4
+Q50    IRLML6344TRPBF N-channel MOSFET, 30V, 5A, SOT-23 package
+R40    220nF capacitor (not resistor!)
+R45    1K5
+R50    15K
+R51,R53        0R00 (zero-ohm link)
+R55    1R0 (can safely measure currents from ~8 mA up, for smaller currents use higher value)
+U1     ATtiny45-20SU
+U2     MCP1703T-5V
+
+
+Firmware:
+
+The firmware is a dumbed-down version of firmware for my other
+project: http://www.fi.muni.cz/~kas/bike-lights/, modified
+for ATtiny45.
+