Q&A Token Response Bits Table

Versal Adaptive SoC Technical Reference Manual (AM011)

Document ID

AM011

Release Date

2023-10-05

Revision

1.6 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
Response 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]