diff --git a/examples/pcf8591_adc_example.py b/examples/pcf8591_adc_example.py
index 72b3346..c7a809e 100644
--- a/examples/pcf8591_adc_example.py
+++ b/examples/pcf8591_adc_example.py
@@ -14,7 +14,8 @@
 # normal power and I2C connections. The voltage level should be between 0V/GND and VCC
 #
 ########################################
-i2c = board.I2C()
+i2c = board.I2C()  # uses board.SCL and board.SDA
+# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
 pcf = PCF8591(i2c)
 
 channel_a = 0
diff --git a/examples/pcf8591_analog_in.py b/examples/pcf8591_analog_in.py
index 7bb901f..0add4ba 100644
--- a/examples/pcf8591_analog_in.py
+++ b/examples/pcf8591_analog_in.py
@@ -18,7 +18,8 @@
 #
 ########################################
 
-i2c = board.I2C()
+i2c = board.I2C()  # uses board.SCL and board.SDA
+# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
 pcf = PCF.PCF8591(i2c)
 
 pcf_in_0 = AnalogIn(pcf, PCF.A0)
diff --git a/examples/pcf8591_dac_example.py b/examples/pcf8591_dac_example.py
index 9f4ea7d..495f672 100644
--- a/examples/pcf8591_dac_example.py
+++ b/examples/pcf8591_dac_example.py
@@ -15,7 +15,8 @@
 # normal power and I2C connections
 #
 ########################################
-i2c = board.I2C()
+i2c = board.I2C()  # uses board.SCL and board.SDA
+# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
 
 pcf = PCF8591(i2c)
 print("enabling DAC")
diff --git a/examples/pcf8591_simpletest.py b/examples/pcf8591_simpletest.py
index 05b4ade..6fc7ddf 100644
--- a/examples/pcf8591_simpletest.py
+++ b/examples/pcf8591_simpletest.py
@@ -18,7 +18,8 @@
 # normal power and I2C connections
 #
 #####################################################################
-i2c = board.I2C()
+i2c = board.I2C()  # uses board.SCL and board.SDA
+# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
 pcf = PCF.PCF8591(i2c)
 
 pcf_in_0 = AnalogIn(pcf, PCF.A0)