diff --git a/circuitpython/code/boot.py b/circuitpython/code/boot.py
index 596b5cc..11b860a 100644
--- a/circuitpython/code/boot.py
+++ b/circuitpython/code/boot.py
@@ -4,13 +4,14 @@ import board
 import digitalio
 import storage
 
-switch = digitalio.DigitalInOut(board.D5)
-switch.direction = digitalio.Direction.INPUT
-switch.pull = digitalio.Pull.UP
+jumper = digitalio.DigitalInOut(board.D5)
+jumper.direction = digitalio.Direction.INPUT
+jumper.pull = digitalio.Pull.UP
 led = digitalio.DigitalInOut(board.D13)
 led.direction = digitalio.Direction.OUTPUT
 
 # If the D0 is connected to ground with a wire
 # CircuitPython can write to the drive
-storage.remount("/", switch.value)
-led.value = switch.value
+storage.remount("/", jumper.value)
+led.value = jumper.value
+print("Read-only:{}".format(jumper.value))
diff --git a/circuitpython/code/main.py b/circuitpython/code/main.py
index 391f20f..98f2b19 100644
--- a/circuitpython/code/main.py
+++ b/circuitpython/code/main.py
@@ -18,7 +18,7 @@
 Author : Pierrick "Arofarn" Couturier
 
 Use with:
- * Adafruit Feather M0 Express (CircuitPython firmware)
+ * Adafruit Feather M4 Express (CircuitPython firmware)
  * Adafruit Ultimate GPS FeatherWing
  * Bosch BME280 sensor (air temperature, humidity, atmospheric pressure) on I2C
 
@@ -45,7 +45,7 @@ neopixel_max_value =const(70) #max value instead of brightness to spare some mem
 
 #######################
 
-import microcontroller
+import microcontroller, board
 import gc, os
 # import micropython
 import time, rtc
@@ -200,14 +200,21 @@ class Data:
 
 def check_data_dir():
     """Check if data directories exists"""
-    if 'data' not in os.listdir():
-        os.mkdir('data')
-        os.mkdir('data/hourly')
-        os.mkdir('data/daily')
-    elif 'hourly' not in os.listdir('data'):
-        os.mkdir('data/hourly')
-    elif 'daily' not in os.listdir('data'):
-        os.mkdir('data/daily')
+    try:
+        if 'data' not in os.listdir():
+            os.mkdir('data')
+            os.mkdir('data/hourly')
+            os.mkdir('data/daily')
+        elif 'hourly' not in os.listdir('data'):
+            os.mkdir('data/hourly')
+        elif 'daily' not in os.listdir('data'):
+            os.mkdir('data/daily')
+    except OSError as e:
+        print("Err {}: readonly".format(e))
+        backup_data = False      #to avoid trying again till next reset
+        # Turn onboard led on to indicate read-only error
+        led13.value = True
+
 
 def set_clock_from_GPS(treshold=5.0):
     """Compare internal RTC and date-time from GPS (if enable and fixed) and set
@@ -255,28 +262,28 @@ clock = rtc.RTC()
 #clock.datetime = time.struct_time((2018, 7, 29, 15, 31, 30, 0, 0, 0))
 
 # BME280 sensors (I2C)
-i2c = I2C(microcontroller.pin.PA23, microcontroller.pin.PA22)
+i2c = I2C(board.SCL, board.SDA)
 # i2c addresses for BME280 breakout :
 #   0x77 = adafruit breakout board
 #   0x76 = tiny chinese board
 bme280 = Adafruit_BME280_I2C(i2c, address=0x76)
 
 # Battery voltage
-vbat = AnalogIn(microcontroller.pin.PA07)
+vbat = AnalogIn(board.VOLTAGE_MONITOR)
 
 #Set the pin to control the power to GPS module
-gps_en_pin = DigitalInOut(microcontroller.pin.PB02)
+gps_en_pin = DigitalInOut(board.A5)
 gps_en_pin.direction = Direction.OUTPUT
 
 #Set the pin N°13 to use the onboard LED as read-only/read-write indicator
-led13 = DigitalInOut(microcontroller.pin.PA17)
+led13 = DigitalInOut(board.D13)
 led13.direction = Direction.OUTPUT
 led13.value = False
 
 # Set GPS module on FeatherWing board
 gps_en_pin.value = not gps_enable  #Set enable pin high to disable GPS module
 if gps_enable:
-    gps_uart = UART(microcontroller.pin.PA10, microcontroller.pin.PA11,
+    gps_uart = UART(board.TX, board.RX,
                     baudrate=9600, timeout=3000)
     gps = GPS(gps_uart)
     # Turn on the basic GGA and RMC info
@@ -285,16 +292,16 @@ if gps_enable:
 
 # Second UART to communicate with raspberry pi (throught GPIO)
 if send_json_data:
-    rpi_uart = UART(microcontroller.pin.PB10, microcontroller.pin.PB11,
+    rpi_uart = UART(board.D10, board.D11,
                     baudrate=115200, timeout=2000)
 
 # Set onboard Neopixel : used as atmo data output
 #  brightness is fixed to 1 to spare some memory. Use neopixel_max_value instead
 if data_to_neopixel:
-    pixel = neopixel.NeoPixel(microcontroller.pin.PA06, 1, brightness=1)
+    pixel = neopixel.NeoPixel(board.NEOPIXEL, 1, brightness=1)
 else:
     #if neopixel is disable : turn off the LED
-    pixel = neopixel.NeoPixel(microcontroller.pin.PA06, 1, brightness=1)
+    pixel = neopixel.NeoPixel(board.NEOPIXEL, 1, brightness=1)
     pixel[0] = (0,0,0)
     pixel = None