2.2 Decoding

To decode the received data, the parity is calculated over the received data and compared to the received parity. If the calculated parity is equal to the received parity, the user data are received correctly. Otherwise, an XOR-operation of calculated and received parity gives information about the error position.
Table 2-3. Decoding
Pcalc ⊕ Prec Data to Correct Comment
0 — Data correct
1 P1 Parity bit error
2 P2 Parity bit error
3 d7 Data bit error
4 P4 Parity bit error
5 d6 Data bit error
6 d5 Data bit error
7 d4 Data bit error
8 P8 Parity bit error
9 d3 Data bit error
10 d2 Data bit error
11 d1 Data bit error
12 d0 Data bit error
13 — Uncorrectable error
14 — Uncorrectable error
15 — Uncorrectable error
Example:
  • Received data = 0x574 (d1 swapped)
  • Prec = 0x4
  • Pcalc = 0xF (For more details, refer to 2.1 Encoding for parity calculation)
  • Pcalc ⊕ Prec = 0xB (data bit d1 swapped)
  • Corrected user data = 0x55