CRC8 check update

AHT20_sensor_control/AHT20_sensor_wrapper.py

@@ -195,9 +195,9 @@ def CheckCRC(self):
         """
         # Get all 6 bytes data and 1 bytes CRC code
         frame_for_CRC8_check = 0x00
-        for i in range(0, 7):
-            frame_for_CRC8_check << 8 | self.all_data[i]
-        isCRCOK = AHT20_crc8_check(frame_for_CRC8_check)
+        # for i in range(0, 7):
+        #     frame_for_CRC8_check << 8 | self.all_data[i]
+        isCRCOK = AHT20_crc8_check(self.all_data)
         if (isCRCOK):
             return AHT20Status.AHT20_CRCOK
         else:

AHT20_sensor_control/crc8_helper.py

@@ -1,6 +1,49 @@
+# A total of 6 * 8 bits data need to check
+N_DATA = 6
+# 1 * 8 bits CRC
+N_CRC = 1
+# Initial value. Equal to bit negation the first data (status of AHT20)
+INIT = 0xFF
+# Useful value to help calculate
+LAST_8_bit = 0xFF
 
-def AHT20_crc8_check(int_data):
+
+# Devide number retrieve from CRC-8 MAXIM G(x) = x8 + x5 + x4 + 1
+CRC_DEVIDE_NUMBER = 0x131
+
+# Data and CRC taken from AHT20, use this for testing?
+TEST_DATA = [[28, 184, 245, 165, 156, 208, 163], [28, 185, 16, 149, 156, 83, 112], [
+    28, 184, 249, 85, 156, 114, 213], [28, 185, 9, 53, 156, 54, 45], [28, 185, 70, 117, 156, 189, 33]
+, [28, 185, 64, 165, 156, 61, 209]]
+
+
+def AHT20_crc8_check(all_data_int, init_value=0xFF):
+    """
+    The input data shoule be:
+    Status Humidity0 Humidity1 Humidity2|Temperature0 Temperature1 Temperature2 CRCCode
+    In python's int64.
+    """
+    # Preprocess all the data and CRCCode from AHT20
+    DATA_FROM_AHT20 = 0x00
+    # Preprocessing the first data (status)
+    DATA_FROM_AHT20 = DATA_FROM_AHT20 | all_data_int[0]
+    print(bin(DATA_FROM_AHT20))
+    DATA_FROM_AHT20 = DATA_FROM_AHT20 ^ init_value
+    print(bin(DATA_FROM_AHT20))
+    for i_data in range(1, N_DATA + N_CRC):
+        DATA_FROM_AHT20 = DATA_FROM_AHT20 << 8 | all_data_int[i_data]
+    print(bin(DATA_FROM_AHT20))
+    mod_value = DATA_FROM_AHT20 % CRC_DEVIDE_NUMBER
+    print(mod_value)
+    if (mod_value == 0):
+        return True
+    else:
+        return False
+
+
+def AHT20_crc8_calculate(all_data_int):
     pass
 
-def AHT20_crc_calculate(int_data):
-    pass
+if __name__ == "__main__":
+    for data in TEST_DATA:
+        AHT20_crc8_check(data, INIT)