tool/mbed/mbed-sdk/workspace_tools/host_tests/wait_us_auto.py

   1 """
   2 mbed SDK
   3 Copyright (c) 2011-2013 ARM Limited
   4
   5 Licensed under the Apache License, Version 2.0 (the "License");
   6 you may not use this file except in compliance with the License.
   7 You may obtain a copy of the License at
   8
   9     http://www.apache.org/licenses/LICENSE-2.0
  10
  11 Unless required by applicable law or agreed to in writing, software
  12 distributed under the License is distributed on an "AS IS" BASIS,
  13 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 See the License for the specific language governing permissions and
  15 limitations under the License.
  16 """
  17
  18 from time import time
  19
  20 class WaitusTest():
  21     """ This test is reading single characters from stdio
  22         and measures time between their occurrences.
  23     """
  24     TICK_LOOP_COUNTER = 13
  25     TICK_LOOP_SUCCESSFUL_COUNTS = 10
  26     DEVIATION = 0.10    # +/-10%
  27
  28     def test(self, selftest):
  29         test_result = True
  30         # First character to start test (to know after reset when test starts)
  31         if selftest.mbed.set_serial_timeout(None) is None:
  32             return selftest.RESULT_IO_SERIAL
  33         c = selftest.mbed.serial_read(1)
  34         if c is None:
  35             return selftest.RESULT_IO_SERIAL
  36         if c == '$': # target will printout TargetID e.g.: $$$$1040e649d5c09a09a3f6bc568adef61375c6
  37             #Read additional 39 bytes of TargetID
  38             if selftest.mbed.serial_read(39) is None:
  39                 return selftest.RESULT_IO_SERIAL
  40             c = selftest.mbed.serial_read(1) # Re-read first 'tick'
  41             if c is None:
  42                 return selftest.RESULT_IO_SERIAL
  43         start_serial_pool = time()
  44         start = time()
  45
  46         success_counter = 0
  47
  48         for i in range(0, self.TICK_LOOP_COUNTER):
  49             c = selftest.mbed.serial_read(1)
  50             if c is None:
  51                 return selftest.RESULT_IO_SERIAL
  52             delta = time() - start
  53             deviation = abs(delta - 1)
  54             # Round values
  55             delta = round(delta, 2)
  56             deviation = round(deviation, 2)
  57             # Check if time measurements are in given range
  58             deviation_ok = True if delta > 0 and deviation <= self.DEVIATION else False
  59             success_counter = success_counter+1 if deviation_ok else 0
  60             msg = "OK" if deviation_ok else "FAIL"
  61             selftest.notify("%s in %.2f sec (%.2f) [%s]"% (c, delta, deviation, msg))
  62             start = time()
  63             if success_counter >= self.TICK_LOOP_SUCCESSFUL_COUNTS:
  64                 break
  65         measurement_time = time() - start_serial_pool
  66         selftest.notify("Consecutive OK timer reads: %d"% success_counter)
  67         selftest.notify("Completed in %.2f sec" % (measurement_time))
  68         test_result = True if success_counter >= self.TICK_LOOP_SUCCESSFUL_COUNTS else False
  69         return selftest.RESULT_SUCCESS if test_result else selftest.RESULT_FAILURE