add basic class with uart xfer

Author: caternuson

adafruit_rockblock.py

@@ -42,7 +42,29 @@
 
 """
 
-# imports
-
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_RockBlock.git"
+
+class RockBlock:
+    '''Driver for RockBLOCK Iridium satellite modem.'''
+
+    def __init__(self, uart, baudrate=19200):
+        self._uart = uart
+        self._uart.baudrate = baudrate
+
+    def _uart_xfer(self, cmd):
+        '''Send AT command and return response.'''
+        # response  = ATCMD\r\nRESP\r\n\r\nOK\r\n
+        #       or  = ATCMD\r\nERROR\r\n
+
+        cmd = str.encode('AT'+cmd)
+
+        self._uart.reset_input_buffer()
+        self._uart.write(cmd+'\r')
+
+        resp = None
+        if self._uart.readline().strip() == cmd:
+            resp = self._uart.readline().strip().decode()
+
+        self._uart.reset_input_buffer()
+        return resp