Add altimeter example data.

.gitignore

@@ -34,7 +34,6 @@
 *.app
 *.i*86
 *.x86_64
-*.hex
 
 # Debug files
 *.dSYM/

apps/altimeter/README.md

@@ -1,6 +1,8 @@
 # Filesystem
 This is a simple altimeter based on LittleFS and BMP390. This is using the built-in Raspberry Pi Pico as non-volatile memory.
 
+![](./example_data/altitude.png)
+
 ### Dependencies
 - [littlefs](/lib/littlefs) Library.
 - [bmp390](/lib/bmp390) Library.

apps/altimeter/visualize.py

@@ -4,6 +4,7 @@ from matplotlib.ticker import FormatStrFormatter
 
 # Convert HEX file to BIN.
 # cat D4.hex | xxd -r -p > D4.bin
+# Checkout example_data for data examples.
 
 data = np.fromfile('./D5.bin', dtype=np.float32)
 temp_x = data[0::2]