Additional examples for specific h/w by our interns (#171)

adc/microphone_adc - Read analog values from a microphone and plot the measured sound amplitude.
i2c/bmp280_i2c - Read and convert temperature and pressure data from a BMP280 sensor, attached to an I2C bus.
i2c/lis3dh_i2c - Read acceleration and temperature value from a LIS3DH sensor via I2C
i2c/mcp9808_i2c - Read temperature, set limits and raise alerts when limits are surpassed.
i2c/mma8451_i2c - Read acceleration from a MMA8451 accelerometer and set range and precision for the data.
i2c/mpl3115a2_i2c - Interface with an MPL3115A2 altimeter, exploring interrupts and advanced board features, via I2C.
i2c/oled_i2c - Convert and display a bitmap on a 128x32 SSD1306-driven OLED display
i2c/pa1010d_i2c - Read GPS location data, parse and display data via I2C.
i2c/pcf8523_i2c - Read time and date values from a real time clock. Set current time and alarms on it.
uart/lcd_uart - Display text and symbols on a 16x02 RGB LCD display via UART

adc/microphone_adc/plotter.py

@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+
+# Grabs raw data from the Pico's UART and plots it as received
+
+# Install dependencies:
+# python3 -m pip install pyserial matplotlib
+
+# Usage: python3 plotter <port>
+# eg. python3 plotter /dev/ttyACM0
+
+# see matplotlib animation API for more: https://matplotlib.org/stable/api/animation_api.html
+
+import serial
+import sys
+import matplotlib.pyplot as plt
+import matplotlib.animation as animation
+from matplotlib.lines import Line2D
+
+# disable toolbar
+plt.rcParams['toolbar'] = 'None'
+
+class Plotter:
+    def __init__(self, ax):
+        self.ax = ax
+        self.maxt = 250
+        self.tdata = [0]
+        self.ydata = [3.3/2]
+        self.line = Line2D(self.tdata, self.ydata)
+
+        self.ax.add_line(self.line)
+        self.ax.set_ylim(0, 3.3)
+        self.ax.set_xlim(0, self.maxt)
+
+    def update(self, y):
+        lastt = self.tdata[-1]
+        if lastt - self.tdata[0] >= self.maxt:  # drop old frames
+            self.tdata = self.tdata[1:]
+            self.ydata = self.ydata[1:]
+            self.ax.set_xlim(self.tdata[0], self.tdata[0] + self.maxt)
+
+        t = lastt + 1
+        self.tdata.append(t)
+        self.ydata.append(y)
+        self.line.set_data(self.tdata, self.ydata)
+        return self.line,
+
+
+def serial_getter():
+    # grab fresh ADC values
+    # note sometimes UART drops chars so we try a max of 5 times
+    # to get proper data
+    while True:
+        for i in range(5):
+            line = ser.readline()
+            try:
+                line = float(line)
+            except ValueError:
+                continue
+            break
+        yield line
+
+if len(sys.argv) < 2:
+    raise Exception("Ruh roh..no port specified!")
+
+ser = serial.Serial(sys.argv[1], 115200, timeout=1)
+
+fig, ax = plt.subplots()
+plotter = Plotter(ax)
+
+ani = animation.FuncAnimation(fig, plotter.update, serial_getter, interval=1,
+                              blit=True, cache_frame_data=False)
+
+ax.set_xlabel("Samples")
+ax.set_ylabel("Voltage (V)")
+fig.canvas.manager.set_window_title('Microphone ADC example')
+fig.tight_layout()
+plt.show()