Q&A Token Response Bits Table

Versal ACAP Technical Reference Manual (AM011)

Document ID
AM011
Release Date
2022-04-26
Revision
1.4 English

There are eight response bits for each byte-write to the watchdog timer. The response bit is calculated using a modulus-2 based arithmetic to get a single bit result (example: 1 ⊕ 1 ⊕ 1 = 1).

  • The 4-bit feedback value is from the Token_FB [FDBK] bit field.
  • The 4-bit token value is from the Token_FB [TVAL] bit field.
  • The 2-bit count value is from the Enable_and_Status [ACNT] bit field.

Software writes the 8-bit response value in proper succession to the Token_Resp [ANS] bit field.

Table 1. SWDT Q&A Token Response Value Calculations
Response Value Feedback [1:0] Value
00 01 10 11
Bit 0

Count[1] ⊕
Token[0] ⊕
Token[3]

Count[1] ⊕
Token[0] ⊕
Token[1]

Count[1] ⊕
Token[1] ⊕
Token[2]

Count[1] ⊕
Token[2] ⊕
Token[3]

Bit 1

Count[1] ⊕
Token[0] ⊕
Token[1] ⊕
Token[2]

Count[1] ⊕
Token[0] ⊕
Token[1] ⊕ Token[1]

Count[1] ⊕
Token[2] ⊕
Token[1] ⊕ Token[1]

Count[1] ⊕
Token[1] ⊕
Token[3] ⊕ Token[3]

Bit 2

Count[1] ⊕
Token[0] ⊕
Token[1] ⊕
Token[3]

Count[1] ⊕
Token[0] ⊕
Token[1] ⊕ Token[1]

Count[1] ⊕
Token[2] ⊕
Token[1] ⊕ Token[1]

Count[1] ⊕
Token[1] ⊕
Token[2] ⊕
Token[3]

Bit 3

Count[1] ⊕
Token[0] ⊕
Token[2] ⊕
Token[3]

Count[1] ⊕
Token[0] ⊕
Token[1] ⊕
Token[3]

Count[1] ⊕
Token[1] ⊕
Token[2] ⊕
Token[3]

Count[1] ⊕
Token[3] ⊕
Token[3] ⊕ Token[3]

Bit 4

Count[0] ⊕
Token[1]

Count[0] ⊕
Token[0]

Count[0] ⊕
Token[2]

Count[0] ⊕
Token[3]

Bit 5

Count[0] ⊕
Token[3]

Count[0] ⊕
Token[0]

Count[0] ⊕
Token[1]

Count[0] ⊕
Token[2]

Bit 6

Count[0] ⊕
Token[0]

Count[0] ⊕
Token[1]

Count[0] ⊕
Token[2]

Count[0] ⊕
Token[3]

Bit 7

Count[0] ⊕
Token[2]

Count[0] ⊕
Token[0]

Count[0] ⊕
Token[1]

Count[0] ⊕
Token[2]