diff --git a/docs/advanced-labs/21-botton-callback.md b/docs/advanced-labs/21-botton-callback.md
new file mode 100644
index 000000000..e6d30affd
--- /dev/null
+++ b/docs/advanced-labs/21-botton-callback.md
@@ -0,0 +1,24 @@
+# Button Callback
+
+```py
+import re
+
+def extract_gpio_pin(input_string):
+    # Use a regular expression to find the GPIO number
+    match = re.search(r"GPIO(\d+)", input_string)
+    if match:
+        # Convert the extracted number to an integer to remove leading zeros
+        return int(match.group(1))
+    else:
+        # Return None if no match is found (or raise an exception if that's preferable)
+        return None
+
+# Test the function with examples
+print(extract_gpio_pin("Pin(GPIO15, mode=IN, pull=PULL_UP)"))  # Output: 15
+print(extract_gpio_pin("Pin(GPIO7, mode=IN, pull=PULL_UP)"))   # Output: 7
+print(extract_gpio_pin("Pin(GPIO03, mode=IN, pull=PULL_UP)"))  # Output: 3
+
+```
+
+
+https://chat.openai.com/share/6e6d8123-ed4d-4dc6-a915-030fe2245dfe
\ No newline at end of file
diff --git a/src/20-sound-test.py b/src/20-sound-test.py
new file mode 100644
index 000000000..cae2fc7db
--- /dev/null
+++ b/src/20-sound-test.py
@@ -0,0 +1,51 @@
+import machine
+import utime
+from machine import Pin, ADC, SPI
+import ssd1306
+
+# OLED display width and height
+WIDTH = 128
+HEIGHT = 64
+
+# SPI pins for OLED
+clock = Pin(2) # SCL
+data = Pin(3) # SDA
+RES = Pin(4)
+DC = Pin(5)
+CS = Pin(6)
+
+# Initialize SPI and OLED Display
+spi = SPI(0, sck=clock, mosi=data)
+display = ssd1306.SSD1306_SPI(WIDTH, HEIGHT, spi, DC, RES, CS)
+
+# Initialize ADC for GPIO26 (ADC0)
+adc = ADC(Pin(26))
+
+min=64000
+def plot_signal():
+    global min
+    display.fill(0) # Clear the display
+    old_x = 0
+    old_y = HEIGHT // 2
+
+    # For simplicity, we're plotting every other pixel
+    for x in range(0, WIDTH):
+        # Read from ADC (values will be from 0 to 4095)
+        val = adc.read_u16()
+        if val < min:
+            min = val
+        # print(val-min)
+        # Scale the ADC value to fit the OLED height
+        y = int(((val-min) / 500) * HEIGHT)
+        # Invert y to plot correctly on the OLED
+        y = HEIGHT - y
+        # Draw a line from the last point to the new point
+        display.line(old_x, old_y, x, y, 1)
+        old_x, old_y = x, y
+
+    display.show() # Update the display with the new data
+
+while True:
+    plot_signal()
+    utime.sleep(0.1) # Small delay to reduce flickering
+
diff --git a/src/advanced/spectrum-analyzer/02-pot-gain.py b/src/advanced/spectrum-analyzer/02-pot-gain.py
new file mode 100644
index 000000000..69e6f1b23
--- /dev/null
+++ b/src/advanced/spectrum-analyzer/02-pot-gain.py
@@ -0,0 +1,53 @@
+import machine
+import utime
+from machine import Pin, ADC, SPI
+import ssd1306
+
+# OLED display width and height
+WIDTH = 128
+HEIGHT = 64
+
+# SPI pins for OLED
+clock = Pin(2)  # SCL
+data = Pin(3)  # SDA
+RES = Pin(4)
+DC = Pin(5)
+CS = Pin(6)
+
+# Initialize SPI and OLED Display
+spi = SPI(0, sck=clock, mosi=data)
+display = ssd1306.SSD1306_SPI(WIDTH, HEIGHT, spi, DC, RES, CS)
+
+# Initialize ADC for sound input (GPIO26) and gain control (GPIO27)
+sound = ADC(Pin(26))
+gain = ADC(Pin(27))
+
+def plot_signal_with_gain():
+    display.fill(0)  # Clear the display
+    old_x = 0
+    old_y = HEIGHT // 2
+
+    # Read gain control (potentiometer) value
+    gain_value = gain.read_u16() + 1  # Adding 1 to avoid division by zero
+
+    for x in range(0, WIDTH, 2):
+        # Read from ADC (sound input)
+        val = sound.read_u16()
+
+        # Adjust the sound value based on the gain
+        # Note: This scaling might need adjustment depending on your specific potentiometer and desired sensitivity
+        adjusted_val = min(((val * gain_value) >> 16), 65535)  # Ensure the adjusted value does not exceed ADC's max value
+
+        # Scale the adjusted value to fit the OLED height
+        y = int((adjusted_val / 65535) * HEIGHT)
+        # Invert y to plot correctly on the OLED
+        y = HEIGHT - y
+        # Draw a line from the last point to the new point
+        display.line(old_x, old_y, x, y, 1)
+        old_x, old_y = x, y
+
+    display.show()  # Update the display with the new data
+
+while True:
+    plot_signal_with_gain()
+    utime.sleep(0.1)  # Small delay to reduce flickering
diff --git a/src/advanced/spectrum-analyzer/23-average-plot.py b/src/advanced/spectrum-analyzer/23-average-plot.py
new file mode 100644
index 000000000..1b1e976fa
--- /dev/null
+++ b/src/advanced/spectrum-analyzer/23-average-plot.py
@@ -0,0 +1,62 @@
+import machine
+import utime
+from machine import Pin, ADC, SPI
+# https://docs.micropython.org/en/latest/esp8266/tutorial/ssd1306.html
+import ssd1306
+
+# OLED display width and height
+WIDTH = 128
+HEIGHT = 64
+
+# SPI pins for OLED
+clock = Pin(2) # SCL
+data = Pin(3) # SDA
+RES = Pin(4)
+DC = Pin(5)
+CS = Pin(6)
+
+# Initialize SPI and OLED Display
+spi = SPI(0, sck=clock, mosi=data)
+display = ssd1306.SSD1306_SPI(WIDTH, HEIGHT, spi, DC, RES, CS)
+
+# Initialize ADC for GPIO26 (ADC0)
+adc = ADC(Pin(26))
+
+
+
+def plot_signal(new_val, min):
+    # Scroll the display content to the left by one pixel
+    display.scroll(-1, 0)
+    y = HEIGHT - new_val//4
+    if y > HEIGHT:
+        y = HEIGHT
+    if y < 0:
+        y = 0
+
+    for clear_y in range(HEIGHT):
+        display.pixel(WIDTH - 2, y, 1)
+
+    # Update the display with the new data
+    # display.fill_rect(0, 54, 100, 63, 0)
+    # display.text(str(min), 0, 54, 1)
+    # display.text(str(new_val), 0, 54, 1)
+    display.show()
+
+min = 53000
+avg = 50
+display.fill(0)
+while True:
+    
+    # add up the ave number of points
+    val=0
+    for i in range(0,avg):
+        val += (adc.read_u16() - min)
+    avg_val = val//avg
+    
+    # if the average val is negative, lower the minimum by that amoun
+    if avg_val < 0:
+        min += avg_val
+    
+    plot_signal(avg_val, min)
+    # utime.sleep(0.1) # Small delay to reduce flickering
+