Add readme.

Makefile

@@ -1,6 +1,6 @@
 CROSS_COMPILE ?=
 
-TARGET_FILE ?= distance_app
+TARGET_FILE ?= voltage_app
 
 CC = $(CROSS_COMPILE)gcc
 CPP = $(CROSS_COMPILE)cpp
@@ -16,7 +16,7 @@ UNIT_TEST_SRC_DIR = test/unit
 UNIT_TEST_OBJ_DIR = $(OBJ_DIR)/$(UNIT_TEST_SRC_DIR)
 
 PREFIX ?= /usr
-BIN_INSTALL_DIR ?= $(PREFIX)/bin/$(TARGET_FILE)
+BIN_INSTALL_DIR = $(PREFIX)/bin
 
 INCLUDES := inc
 INCLUDES += $(PREFIX)/include/
@@ -57,7 +57,7 @@ all: $(TARGET)
 
 install: all
 	install -d $(BIN_INSTALL_DIR)
-	install -m 0644 $(TARGET) $(BIN_INSTALL_DIR)
+	install -m 0666 $(TARGET) $(BIN_INSTALL_DIR)
 
 uninstall:
 	rm -f $(BIN_INSTALL_DIR)/$(TARGET_FILE)

README.md

@@ -0,0 +1,67 @@
+# Voltage app
+
+Application to read out voltages from ads1115 adc-i2c ad converter.
+
+## Dependencies
+
+* `gpio_sys`: <https://git.blackfinn.de/adc_gpio_i2c/gpio_sys>
+* `i2c_bb`: <https://git.blackfinn.de/adc_gpio_i2c/i2c_bb>
+* `ads1115`: <https://git.blackfinn.de/adc_gpio_i2c/ads1115>
+
+## Installation
+
+```shell
+make install
+```
+
+Installs `voltage_app` into the directory `$(PREFIX)/bin/`. The default value for `PREFIX` is: `PREFIX=/usr`. To use another location for installation changing the value of the `PREFIX` variable is needed. E.g.:
+
+```shell
+PREFIX=/usr/local/ make install
+```
+
+## Uninstallation
+
+```shell
+make uninstall
+```
+
+Removes the files installed with the `install` make target.  
+> **NOTE:** If `PREFIX` variable was changed during installation process the same value needs to be set for uninstallation. E.g.:
+
+```shell
+PREFIX=/usr/local/ make uninstall
+```
+
+## Example
+
+```shell
+$ distance_app
+Conversation: 3.196V (0x4293).
+Conversation: 3.199V (0x42a7).
+Conversation: 3.192V (0x4282).
+Conversation: 3.186V (0x4261).
+Conversation: 3.183V (0x424e).
+Conversation: 3.185V (0x425b).
+Conversation: 3.178V (0x4236).
+Conversation: 3.178V (0x4235).
+Conversation: 3.190V (0x4275).
+Conversation: 3.181V (0x4243).
+Conversation: 3.178V (0x4235).
+^CSignal catched: 2
+ Shutting down...
+```
+
+## Additional make targets
+
+| Target          | Meaning                                           |
+| --------------- | ------------------------------------------------- |
+| all             | Build the code, link the application executable.  |
+| install         | Install the application executable.               |
+| uninstall       | Uninstall the application executable.             |
+| clean           | Clean up build artifacts.                         |
+| distclean       | Remove all folders created during any build step. |
+| build_unit_test | Build the unit tests.                             |
+| exec_unit_test  | Execute the unit tests.                           |
+| coverage        | Determine code coverage of the unit tests.        |
+| check           | Static code analysis (cppcheck).                  |