Rainer Raul / Mbed 2 deprecated OneWireDrv

Test 1-wire , working wtih parasite power and few sensors with mixed power supply.

Dependencies:   mbed

crc8.cpp@1:f8aa0ff8d04a, 2022-05-18 (annotated)

Committer:
rainerraul
Date:
Wed May 18 10:09:56 2022 +0000
Revision:
1:f8aa0ff8d04a
Parent:
0:1197076b78f4 
test

Who changed what in which revision?

UserRevisionLine numberNew contents of line
macraj 0:1197076b78f4 1 #include <inttypes.h>
macraj 0:1197076b78f4 2
macraj 0:1197076b78f4 3 #define CRC8INIT 0x00
macraj 0:1197076b78f4 4 #define CRC8POLY 0x18 //0X18 = X^8+X^5+X^4+X^0
macraj 0:1197076b78f4 5
macraj 0:1197076b78f4 6 uint8_t crc8 ( uint8_t *data_in, uint16_t number_of_bytes_to_read )
macraj 0:1197076b78f4 7 {
macraj 0:1197076b78f4 8 uint8_t crc;
macraj 0:1197076b78f4 9 uint16_t loop_count;
macraj 0:1197076b78f4 10 uint8_t bit_counter;
macraj 0:1197076b78f4 11 uint8_t data;
macraj 0:1197076b78f4 12 uint8_t feedback_bit;
macraj 0:1197076b78f4 13
macraj 0:1197076b78f4 14 crc = CRC8INIT;
macraj 0:1197076b78f4 15
macraj 0:1197076b78f4 16 for (loop_count = 0; loop_count != number_of_bytes_to_read; loop_count++)
macraj 0:1197076b78f4 17 {
macraj 0:1197076b78f4 18 data = data_in[loop_count];
macraj 0:1197076b78f4 19
macraj 0:1197076b78f4 20 bit_counter = 8;
macraj 0:1197076b78f4 21 do {
macraj 0:1197076b78f4 22 feedback_bit = (crc ^ data) & 0x01;
macraj 0:1197076b78f4 23
macraj 0:1197076b78f4 24 if ( feedback_bit == 0x01 ) {
macraj 0:1197076b78f4 25 crc = crc ^ CRC8POLY;
macraj 0:1197076b78f4 26 }
macraj 0:1197076b78f4 27 crc = (crc >> 1) & 0x7F;
macraj 0:1197076b78f4 28 if ( feedback_bit == 0x01 ) {
macraj 0:1197076b78f4 29 crc = crc | 0x80;
macraj 0:1197076b78f4 30 }
macraj 0:1197076b78f4 31
macraj 0:1197076b78f4 32 data = data >> 1;
macraj 0:1197076b78f4 33 bit_counter--;
macraj 0:1197076b78f4 34
macraj 0:1197076b78f4 35 } while (bit_counter > 0);
macraj 0:1197076b78f4 36 }
macraj 0:1197076b78f4 37
macraj 0:1197076b78f4 38 return crc;
macraj 0:1197076b78f4 39 }