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README.md

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 # nucleo32-l432kc-tnc-firmware
 Source code for breadboard TNC based on STM32L432KC Nucleo32 dev board
+
+# Build Instructions for the Breadboard TNC3
+
+The Breadboard TNC3 is a TNC based on the microcontroller family and firmware
+used in the Mobilinkd TNC3.  The breadboard TNC3 contains the microcontroller,
+audio input and output circuitry, PTT signalling circuitry and EEPROM for
+storing configuration that is nearly identical to the TNC3.  It only lacks the
+Bluetooth adapter and battery charging circuitry.
+
+## Bill of Materials
+
+The Breadboard TNC3 is designed around the STMicroelectronics Nucleo32 board
+with the STM32L432KC chip.  The total bill of materials (BOM) cost is about
+$25 (USD).
+
+You will need: