diff --git a/.github/auto_build.sh b/.github/auto_build.sh
new file mode 100644
index 0000000..c2b527e
--- /dev/null
+++ b/.github/auto_build.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -e
+set -x
+
+build_sku () {
+  SKU=$1
+  make clean all DMO_SKU=${SKU}
+  cp build/freedmo.bin freedmo-default-sku-${SKU}.bin
+}
+
+build_sku S0722430
+build_sku S0722550
+build_sku S0722400
+build_sku 1744907
+build_sku 30857
+build_sku 30336
+
+DATE=$(date +'%Y%m%d')
+GIT=$(git describe --tags --abbrev=0)
+zip -9 "freedmo-firmware-all-${DATE}-${GIT}.zip" freedmo-default-sku-*.bin
+
+exit 0
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..745c49e
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,42 @@
+name: 'build'
+
+on:
+  push:
+    branches:
+      - '*'
+      - 'feature/**'
+
+  workflow_dispatch:
+
+jobs:
+
+  job-firmware:
+    name: 'build firmware'
+    runs-on: ubuntu-20.04
+    steps:
+      - name: 'checkout'
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: 'install packages'
+        run: |
+          export DEBIAN_FRONTEND=noninteractive
+          sudo apt-get update
+          sudo apt-get install -y gcc-arm-none-eabi libnewlib-arm-none-eabi
+
+      - name: 'compile firmware'
+        run: bash ./.github/auto_build.sh
+
+      - name: 'release assets'
+        if: startsWith( github.ref, 'refs/tags/releases/')
+        uses: svenstaro/upload-release-action@v2
+        with:
+          repo_token: ${{ secrets.GITHUB_TOKEN }}
+          file: freedmo-firmware-all-*.zip
+          tag: ${{ github.ref }}
+          overwrite: true
+          file_glob: true
+
+
+
diff --git a/COMPILED_FIRMWARE/README.md b/COMPILED_FIRMWARE/README.md
deleted file mode 100644
index a34ebfe..0000000
--- a/COMPILED_FIRMWARE/README.md
+++ /dev/null
@@ -1,12 +0,0 @@
-This is the complete firmware file. 
-
-You can write it to STM32F103 bluepill board with 
-
-- SWD upload using JLink2 and ST JLink Utility
-
-or
-
-- Serial upload using UART adapter and ST FlashLoader Demonstrator
-  This is the same procedure as uploading a USB bootloader:
-    https://www.electronicshub.org/how-to-upload-stm32f103c8t6-usb-bootloader
-    just select the "freedmo.bin" in "Download from file" (2)
diff --git a/COMPILED_FIRMWARE/freedmo.bin b/COMPILED_FIRMWARE/freedmo.bin
deleted file mode 100644
index abbbd18..0000000
Binary files a/COMPILED_FIRMWARE/freedmo.bin and /dev/null differ
diff --git a/Makefile b/Makefile
index 6401152..839e623 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,8 @@
-GCC_PATH = ./gcc-arm-none-eabi-10.3-2021.07/bin
+#GCC_PATH = ./gcc-arm-none-eabi-10.3-2021.07/bin
 BUILD_DIR = build
 TARGET = freedmo
 #DEBUG = 1
-OPT = -Os
+OPT = -std=c99 -Wall -Os -DDMO_SKU_$(DMO_SKU)
 
 ######################################
 # source
diff --git a/README.md b/README.md
index 9b7e2ac..22c997b 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 Endless freedom for D.MO 550 series label writer printer.
 
+[![Release](https://img.shields.io/github/release/free-dmo/free-dmo-stm32.svg?maxAge=60)](https://github.com/free-dmo/free-dmo-stm32/releases/latest) <== Click here to download
+
 ## Wiring
 
 Components needed:
@@ -51,8 +53,9 @@ Option 2: Install required ARM toolchain GNU Arm Embedded Toolchain from ARM:
 
 Option 3: Use the precompiled firmware 
 
- * a precompiled firmware binary is available in the `COMPILED_FIRMWARE` folder
-
+ * a precompiled firmware binaries are available here: [Download](https://github.com/free-dmo/free-dmo-stm32/releases/latest)
+ 
+   You can choose one of the firmwares which has a default SKU for emulation (used when no real RFID tag is present)
 
 ## Download the firmware to the STM32F103 bluepill board
 
@@ -107,9 +110,9 @@ You can choose from the list of included label data by selecting the SKU: <br/>
 file: `Src/main.c`
 
 ~~~ C
-#define DMO_SKU  S0722430 // 54 x 101 mm, 220 pcs.
-//#define DMO_SKU  S0722550 // 19 x  51 mm, 500 pcs.
-//#define DMO_SKU  S0722400 // 36 x  89 mm, 50 pcs.
+#define DMO_SKU_S0722430 // 54 x 101 mm, 220 pcs.
+//#define DMO_SKU_S0722550 // 19 x  51 mm, 500 pcs.
+//#define DMO_SKU_S0722400 // 36 x  89 mm, 50 pcs.
 ~~~
 
 Happy printing... 😈
diff --git a/Src/main.c b/Src/main.c
index 806247a..57e2168 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -50,12 +50,12 @@ static void MX_I2C2_Init(void);
 //
 
 //choose between one of the dumped SKU (roll types) for emulation
-#define DMO_SKU  S0722430   //  54 mm x 101 mm / 2.125 in x 4 in / 220 pcs.
-//#define DMO_SKU  S0722550 //  19 mm x  51 mm / 0.75 in x 2 in  / 500 pcs.
-//#define DMO_SKU  S0722400 //  36 mm x  89 mm / 1.4 in x 3.5 in / 50 pcs.
-//#define DMO_SKU  1744907  // 102 mm x 152 mm / 4 in x 6 in     / 220 pcs.
-//#define DMO_SKU  30857    //  57 mm x 104 mm / 2.25 in x 4 in  / 250 pcs.
-//#define DMO_SKU  30336    //  25 mm x  51 mm / 1 in x 2.125 in / 500 pcs.
+//#define DMO_SKU_S0722430  //  54 mm x 101 mm / 2.125 in x 4 in / 220 pcs.
+//#define DMO_SKU_S0722550  //  19 mm x  51 mm / 0.75 in x 2 in  / 500 pcs.
+//#define DMO_SKU_S0722400  //  36 mm x  89 mm / 1.4 in x 3.5 in / 50 pcs.
+//#define DMO_SKU_1744907   // 102 mm x 152 mm / 4 in x 6 in     / 220 pcs.
+//#define DMO_SKU_30857     //  57 mm x 104 mm / 2.25 in x 4 in  / 250 pcs.
+//#define DMO_SKU_30336     //  25 mm x  51 mm / 1 in x 2.125 in / 500 pcs.
 
 //choose one of the dumped original tags for UID + signature emulation. It does not have to match the dumped data
 #define SLIX2_TAG_EMU 1
@@ -91,7 +91,7 @@ static const uint8_t DMO_TAG_SLIX2_SYSINFO[SLIX2_SYSINFO_LEN]     = {0x0F,0xED,0
 static const uint8_t DMO_TAG_SLIX2_SIGNATURE[SLIX2_SIGNATURE_LEN] = {0xAC,0xD4,0x3D,0x48,0xA8,0xDF,0xD5,0xC4,0x07,0xB7,0xEC,0x76,0xE9,0x79,0xBF,0xDA,0x70,0x44,0xDB,0x28,0xCB,0x80,0x6F,0xDD,0x0C,0x06,0x14,0x0E,0x50,0xF8,0x87,0x61};
 #endif
 
-#if DMO_SKU == S0722430
+#if defined (DMO_SKU_S0722430)
 static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //S0722430 54 x 101 mm, 220 pcs.
   0x03,0x0A,0x82,0xED,0x86,0x39,0x61,0xD2,0x03,0x14,0x1E,0x32,0xB6,0xCA,0x00,0x3C,0x27,0xB3,0x98,0xBA,0x53,0x30,0x37,0x32,0x32,0x34,0x33,0x30,0x00,0x00,0x00,0x00,0x00,0xFF,0x04,0x01,0x01,0x00,0x00,0x00,
   0x22,0x04,0x1E,0x00,0x28,0x00,0x00,0x00,0x00,0x00,0x0F,0x00,0xF0,0x03,0x1C,0x02,0x00,0x00,0x00,0x00,0x46,0x02,0xDC,0x00,0x78,0x2D,0x16,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
@@ -102,7 +102,8 @@ static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //S
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x0D,0xFF,0x00,0x01
 };
-#elif DMO_SKU == S0722550
+#endif
+#if defined (DMO_SKU_S0722550)
 static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //S0722550 19 x 51 mm, 500 pcs.
   0x03,0x0A,0x82,0xED,0x86,0x39,0x61,0xD2,0x03,0x14,0x1E,0x32,0xB6,0xCA,0x00,0x3C,0xEE,0x0D,0xBF,0xDF,0x53,0x30,0x37,0x32,0x32,0x35,0x35,0x30,0x00,0x00,0x00,0x00,0x00,0xFF,0x06,0x01,0x01,0x00,0x00,0x00,
   0x29,0x02,0x1E,0x00,0x25,0x00,0x00,0x00,0x00,0x00,0x10,0x00,0xFC,0x01,0x17,0x01,0x00,0x00,0x00,0x00,0x37,0x01,0xF4,0x01,0xF5,0x35,0x32,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
@@ -113,7 +114,8 @@ static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //S
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xD9,0xFD,0x00,0x01
 };
-#elif DMO_SKU == S0722400
+#endif
+#if defined (DMO_SKU_S0722400)
 static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //S0722400 36 x 89 mm, 50 pcs.
   0x03,0x0A,0x82,0xED,0x86,0x39,0x61,0xD2,0x03,0x14,0x1E,0x32,0xB6,0xCA,0x00,0x3C,0x36,0x42,0x0C,0x33,0x53,0x30,0x37,0x32,0x32,0x34,0x30,0x30,0x00,0x00,0x00,0x00,0x00,0xFF,0x04,0x01,0x01,0x00,0x00,0x00,
   0xA3,0x03,0x1E,0x00,0x26,0x00,0x00,0x00,0x00,0x00,0x0F,0x00,0x76,0x03,0x65,0x01,0x00,0x00,0x00,0x00,0x85,0x01,0x34,0x00,0x75,0x09,0x05,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
@@ -124,7 +126,8 @@ static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //S
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xC6,0xFF,0x00,0x01
 };
-#elif DMO_SKU == 1744907
+#endif
+#if defined (DMO_SKU_1744907)
 static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //1744907 102 x 152 mm, 220 pcs.
   0x03,0x0A,0x82,0xED,0x86,0x39,0x61,0xD2,0x03,0x14,0x1E,0x32,0xB6,0xCA,0x00,0x3C,0x86,0x50,0xB6,0x72,0x31,0x37,0x34,0x34,0x39,0x30,0x37,0x00,0x00,0x00,0x00,0x00,0x00,0xFF,0x24,0x01,0x01,0x00,0x00,0x00,
   0x73,0x06,0x1E,0x00,0x26,0x00,0x00,0x00,0x00,0x00,0x10,0x00,0x3A,0x06,0x14,0x04,0x00,0x00,0x00,0x00,0x33,0x04,0xDC,0x00,0xF1,0x46,0x16,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
@@ -135,7 +138,8 @@ static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //1
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x0D,0xFF,0x00,0x01
 };
-#elif DMO_SKU == 30857
+#endif
+#if defined (DMO_SKU_30857)
 static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //30857 57 x 104 mm, 250 pcs.
   0x03,0x0A,0x82,0xED,0x86,0x39,0x61,0xD2,0x03,0x14,0x1E,0x32,0xB6,0xCA,0x00,0x3C,0x06,0x2C,0xC7,0xF8,0x33,0x30,0x38,0x35,0x37,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF,0x24,0x01,0x01,0x00,0x00,0x00,
   0x22,0x04,0x1E,0x00,0x23,0x00,0x00,0x00,0x00,0x00,0x10,0x00,0xF8,0x03,0x4C,0x02,0x00,0x00,0x00,0x00,0x6B,0x02,0xFA,0x00,0xAE,0x33,0x19,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
@@ -146,7 +150,8 @@ static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //3
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
   0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xED,0xFE,0x00,0x01
 };
-elif DMO_SKU == 30336
+#endif
+#if defined (DMO_SKU_30336)
 static const uint8_t DMO_TAG_SLIX2_BLOCKS[SLIX2_BLOCKS*sizeof(uint32_t)] = { //30336 25 x 51 mm, 500 pcs.
   0x03,0x0A,0x82,0xED,0x86,0x39,0x61,0xD2,0x03,0x14,0x1E,0x32,0xB6,0xCA,0x00,0x3C,0x8D,0xBA,0x04,0x96,0x33,0x30,0x33,0x33,0x36,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF,0x24,0x01,0x01,0x00,0x00,0x00,
   0x6B,0x02,0x1E,0x00,0x48,0x00,0x00,0x00,0x00,0x00,0x10,0x00,0x1C,0x02,0xFE,0x00,0x00,0x00,0x00,0x00,0x37,0x01,0xF4,0x01,0x73,0x3C,0x32,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,