tighten up spi timing

Author: ladyada

adafruit_pn532.py

@@ -261,8 +261,6 @@ def _write_frame(self, data):
         # Send frame.
         if self.debug:
             print('Write frame: ', [hex(i) for i in frame])
-        else:
-            time.sleep(0.1)
         self._write_data(bytes(frame))
 
     def _read_frame(self, length):
@@ -275,8 +273,7 @@ def _read_frame(self, length):
         response = self._read_data(length+8)
         if self.debug:
             print('Read frame:', [hex(i) for i in response])
-        else:
-            time.sleep(0.1)
+
         # Swallow all the 0x00 values that preceed 0xFF.
         offset = 0
         while response[offset] == 0x00:
@@ -497,7 +494,7 @@ def _wait_ready(self, timeout=1):
             if status == b'\x01':
                 return True  # No longer busy
             else:
-                time.sleep(0.1)  # lets ask again soon!
+                time.sleep(0.05)  # lets ask again soon!
         # Timed out!
         return False
 
@@ -546,11 +543,12 @@ def _wait_ready(self, timeout=1):
         timestamp = time.monotonic()
         while (time.monotonic() - timestamp) < timeout:
             with self._spi as spi:
+                time.sleep(0.02)   # required
                 spi.write_readinto(status, status)
             if reverse_bit(status[1]) == 0x01:  # LSB data is read in MSB
                 return True      # Not busy anymore!
             else:
-                time.sleep(0.1)  # pause a bit till we ask again
+                time.sleep(0.01)  # pause a bit till we ask again
         # We timed out!
         return False