Rename begin to warm_up and automatically invoke from initializer based on feedback. Warnings given to disable this behavior when explicit initialization is desired.

Author: tdicola

adafruit_thermal_printer/thermal_printer.py

@@ -137,8 +137,8 @@ def __set__(self, obj, val):
         # pylint: enable=protected-access
         # pylint: enable=too-few-public-methods
 
-    def __init__(self, uart, byte_delay_s=0.00057346, dot_feed_s=0.0021,
-                 dot_print_s=0.03):
+    def __init__(self, uart, *, byte_delay_s=0.00057346, dot_feed_s=0.0021,
+                 dot_print_s=0.03, auto_warm_up=True):
         """Thermal printer class.  Requires a serial UART connection with at
         least the TX pin connected.  Take care connecting RX as the printer
         will output a 5V signal which can damage boards!  If RX is unconnected
@@ -147,7 +147,10 @@ def __init__(self, uart, byte_delay_s=0.00057346, dot_feed_s=0.0021,
         and dot_print_s values are delays which are used to prevent overloading
         the printer with data.  Use the default delays unless you fully
         understand the workings of the printer and how delays, baud rate,
-        number of dots, heat time, etc. relate to each other.
+        number of dots, heat time, etc. relate to each other.  Can set
+        auto_warm_up to a boolean value (default True) to automatically call
+        the warm_up function which will initialize the printer (but can take a
+        significant amount of time, on the order 0.5-5 seconds, be warned!).
         """
         self.max_chunk_height = 255
         self._resume = 0
@@ -167,6 +170,8 @@ def __init__(self, uart, byte_delay_s=0.00057346, dot_feed_s=0.0021,
         self._dot_feed_s = dot_feed_s
         self._dot_print_s = dot_print_s
         self.reset()
+        if auto_warm_up:
+            self.warm_up()
 
     def _set_timeout(self, period_s):
         # Set a timeout before future commands can be sent.
@@ -220,10 +225,10 @@ def send_command(self, command):
         """Send a command string to the printer."""
         self._uart.write(command)
 
-    # Do initialization in begin instead of the initializer because this
+    # Do initialization in warm_up instead of the initializer because this
     # initialization takes a long time (5 seconds) and shouldn't happen during
     # object creation (users need explicit control of when to start it).
-    def begin(self, heat_time=120):
+    def warm_up(self, heat_time=120):
         """Initialize the printer.  Can specify an optional heat_time keyword
         to override the default heating timing of 1.2 ms.  See the datasheet
         for details on the heating time value (duration in 10uS increments).

examples/simpletest.py

@@ -3,16 +3,14 @@
 import board
 import busio
 
-# Pick which version thermal printer to import.  Only ONE of these lines should
-# be uncommented depending on the version of your printer.  Hold the button on
-# the printer as it's powered on and it will print a test page that displays
-# the firmware version, like 2.64, 2.68, etc.
-# Use this line for printers with version 2.68 or higher:
-import adafruit_thermal_printer.thermal_printer as thermal_printer
-# Use this line for printers with version 2.64 up to (but not including) 2.68:
-#import adafruit_thermal_printer.thermal_printer_264 as thermal_printer
-# Use this line for printers with version up to (but not including) 2.64:
-#import adafruit_thermal_printer.thermal_printer_legacy as thermal_printer
+import adafruit_thermal_printer
+
+
+# Pick which version thermal printer class to use depending on the version of
+# your printer.  Hold the button on the printer as it's powered on and it will
+# print a test page that displays the firmware version, like 2.64, 2.68, etc.
+# Use this version in the get_printer_class function below.
+ThermalPrinter = adafruit_thermal_printer.get_printer_class(2.69)
 
 # Define RX and TX pins for the board's serial port connected to the printer.
 # Only the TX pin needs to be configued, and note to take care NOT to connect
@@ -28,12 +26,12 @@
 uart = busio.UART(TX, RX, baudrate=19200)
 
 # Create the printer instance.
-printer = thermal_printer.ThermalPrinter(uart)
+printer = ThermalPrinter(uart, auto_warm_up=False)
 
 # Initialize the printer.  Note this will take a few seconds for the printer
 # to warm up and be ready to accept commands (hence calling it explicitly vs.
-# automatically in the initializer above).
-printer.begin()
+# automatically in the initializer with the default auto_warm_up=True).
+printer.warm_up()
 
 # Check if the printer has paper.  This only works if the RX line is connected
 # on your board (but BE CAREFUL as mentioned above this RX line is 5V!)
@@ -57,11 +55,11 @@
 printer.bold = False
 
 # Print a normal/thin underline line of text:
-printer.underline = thermal_printer.UNDERLINE_THIN
+printer.underline = adafruit_thermal_printer.UNDERLINE_THIN
 printer.print('Thin underline!')
 
 # Print a thick underline line of text:
-printer.underline = thermal_printer.UNDERLINE_THICK
+printer.underline = adafruit_thermal_printer.UNDERLINE_THICK
 printer.print('Thick underline!')
 
 # Disable underlines.
@@ -93,26 +91,26 @@
 printer.strike = False
 
 # Print medium size text.
-printer.size = thermal_printer.SIZE_MEDIUM
+printer.size = adafruit_thermal_printer.SIZE_MEDIUM
 printer.print('Medium size text!')
 
 # Print large size text.
-printer.size = thermal_printer.SIZE_LARGE
+printer.size = adafruit_thermal_printer.SIZE_LARGE
 printer.print('Large size text!')
 
 # Back to normal / small size text.
-printer.size = thermal_printer.SIZE_SMALL
+printer.size = adafruit_thermal_printer.SIZE_SMALL
 
 # Print center justified text.
-printer.justify = thermal_printer.JUSTIFY_CENTER
+printer.justify = adafruit_thermal_printer.JUSTIFY_CENTER
 printer.print('Center justified!')
 
 # Print right justified text.
-printer.justify = thermal_printer.JUSTIFY_RIGHT
+printer.justify = adafruit_thermal_printer.JUSTIFY_RIGHT
 printer.print('Right justified!')
 
 # Back to left justified / normal text.
-printer.justify = thermal_printer.JUSTIFY_LEFT
+printer.justify = adafruit_thermal_printer.JUSTIFY_LEFT
 
 # Print a UPC barcode.
 printer.print('UPCA barcode:')