SLLSFE8 Data sheet

SLLSFE8B November 2024 – November 2025 TCAN2845-Q1 , TCAN2847-Q1

PRODUCTION DATA

8.4.8.9.4.3.2 Sequence of the 2-bit Watchdog Answer Counter

The sequence of the 2-bit, watchdog answer-counter is as follows for each counter value:

WD_ANSW_CNT[1:0] = 11b:
1. The watchdog calculates the reference Answer-3.
2. A write access occurs. The MCU writes the Answer-3 byte in WD_QA_ANSWER[7:0].
3. The watchdog compares the reference Answer-3 with the Answer-3 byte in WD_QA_ANSWER[7:0].
4. The watchdog decrements the WD_ANSW_CNT[1:0] bits to 10b and sets the WD_QA_ERR status bit to 1 if the Answer-3 byte is incorrect.
WD_ANSW_CNT[1:0] = 10b:
1. The watchdog calculates the reference Answer-2.
2. A write access occurs. The MCU writes the Answer-2 byte in WD_QA_ANSWER[7:0].
3. The watchdog compares the reference Answer-2 with the Answer-2 byte in WD_QA_ANSWER[7:0].
4. The watchdog decrements the WD_ANSW_CNT[1:0] bits to 01b and sets the WD_QA_ERR status bit to 1 if the Answer-2 byte is incorrect.
WD_ANSW_CNT[1:0] = 01b:
1. The watchdog calculates the reference Answer-1.
2. A write access occurs. The MCU writes the Answer-1 byte in WD_QA_ANSWER[7:0].
3. The watchdog compares the reference Answer-1 with the Answer-1 byte in WD_QA_ANSWER[7:0].
4. The watchdog decrements the WD_ANSW_CNT[1:0] bits to 00b and sets the WD_QA_ERR status bit to 1 if the Answer-1 byte is incorrect.
WD_ANSW_CNT[1:0] = 00b:
1. The watchdog calculates the reference Answer-0.
2. A write access occurs. The MCU writes the Answer-0 byte in WD_QA_ANSWER[7:0].
3. The watchdog compares the reference Answer-0 with the Answer-0 byte in WD_QA_ANSWER[7:0].
4. The watchdog sets the WD_QA_ERR status bit to 1 if the Answer-0 byte is incorrect.
5. The watchdog starts a new watchdog sequence and sets the WD_ANSW_CNT[1:0] to 11b.

The MCU needs to clear the bit by writing a '1' to the WD_QA_ERR bit

Table 8-18 Set of WD Questions and Corresponding WD Answers Using Default Setting

QUESTION IN WD_QA_QUESTION REGISTER	WD ANSWER BYTES (EACH BYTE TO BE WRITTEN INTO WD_QA_ANSWER REGISTER)
QUESTION IN WD_QA_QUESTION REGISTER	WD_ANSWER_RESP_3	WD_ANSWER_RESP_2	WD_ANSWER_RESP_1	WD_ANSWER_RESP_0
WD_QUESTION	WD_ANSW_CNT[1:0] 11b	WD_ANSW_CNT[1:0] 10b	WD_ANSW_CNT[1:0] 01b	WD_ANSW_CNT[1:0] 00b
0x0	FF	0F	F0	00
0x1	B0	40	BF	4F
0x2	E9	19	E6	16
0x3	A6	56	A9	59
0x4	75	85	7A	8A
0x5	3A	CA	35	C5
0x6	63	93	6C	9C
0x7	2C	DC	23	D3
0x8	D2	22	DD	2D
0x9	9D	6D	92	62
0xA	C4	34	CB	3B
0xB	8B	7B	84	74
0xC	58	A8	57	A7
0xD	17	E7	18	E8
0xE	4E	BE	41	B1
0xF	01	F1	0E	FE

TCAN2845-Q1 TCAN2847-Q1 WD Expected Answer
Generation

Figure 8-65 WD Expected Answer Generation

Table 8-19 Correct and Incorrect WD Q&A Sequence Run Scenarios

NUMBER OF WD ANSWERS		ACTION	WD_QA_ERR (in WD_QA_QUESTION Register)⁽¹⁾	COMMENTS
RESPONSE WINDOW 1	RESPONSE WINDOW 2	ACTION	WD_QA_ERR (in WD_QA_QUESTION Register)⁽¹⁾	COMMENTS
0 answer	0 answer	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD question	1b	No answer
0 answer	4 INCORRECT answers	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Total Answers Received = 4
0 answer	4 CORRECT answers	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Total Answers Received = 4
0 answer	1 CORRECT answer	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 CORRECT ANSWERS in RESPONSE WINDOW 1 and 1 CORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] < 4)
1 CORRECT answer	1 CORRECT answer
2 CORRECT answers	1 CORRECT answer
0 answer	1 INCORRECT answer	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 CORRECT ANSWERS in RESPONSE WINDOW 1 and 1 INCORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] < 4)
1 CORRECT answer	1 INCORRECT answer
2 CORRECT answers	1 INCORRECT answer
0 answer	4 CORRECT answers	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 CORRECT ANSWERS in WIN1 and more than 1 CORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] = 4)
1 CORRECT answer	3 CORRECT answers
2 CORRECT answer	2 CORRECT answers
0 answer	4 INCORRECT answers	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 CORRECT ANSWERS in RESPONSE WINDOW 1 and more than 1 INCORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] = 4)
1 CORRECT answer	3 INCORRECT answers
2 CORRECT answers	2 INCORRECT answers
0 answer	3 CORRECT answers	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 INCORRECT ANSWERS in RESPONSE WINDOW 1 and more than 1 CORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] < 4)
1 INCORRECT answer	2 CORRECT answers	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD question	1b
2 INCORRECT answers	1 CORRECT answer		1b
0 answer	3 INCORRECT answers	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 INCORRECT ANSWERS in RESPONSE WINDOW 1 and more than 1 INCORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] < 4)
1 INCORRECT answer	2 INCORRECT answers
2 INCORRECT answers	1 INCORRECT answer
0 answer	4 CORRECT answers	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 INCORRECT ANSWERS in RESPONSE WINDOW 1 and more than 1 CORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] = 4)
1 INCORRECT answer	3 CORRECT answers		1b
2 INCORRECT answers	2 CORRECT answers		1b
0 answer	4 INCORRECT answers	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Less than 3 INCORRECT ANSWERS in RESPONSE WINDOW 1 and more than 1 INCORRECT ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] = 4)
1 INCORRECT answer	3 INCORRECT answers
2 INCORRECT answers	2 INCORRECT answers
3 CORRECT answers	0 answer	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD Question	1b	Less than 4 CORRECT ANSWERS in RESPONSE WINDOW 1 and more than 0 ANSWER in RESPONSE WINDOW 2 (Total WD_ANSW_CNT[1:0] < 4)
2 CORRECT answers	0 answer		1b
1 CORRECT answer	0 answer		1b
3 CORRECT answers	1 CORRECT answer	-New WD cycle starts after the 4th WD answer -Decrement WD failure counter -New WD cycle starts with a new WD question	0b	CORRECT SEQUENCE
3 CORRECT answers	1 INCORRECT answer	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Total Answers Received = 4
3 INCORRECT answers	0 answer	-New WD cycle starts after the end of RESPONSE WINDOW 2 -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Total Answers Received < 4
3 INCORRECT answers	1 CORRECT answer	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Total Answers Received = 4
3 INCORRECT answers	1 INCORRECT answer	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	Total Answers Received = 4
4 CORRECT answers	Not applicable	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b
3 CORRECT answers + 1 INCORRECT answer	Not applicable	-New WD cycle starts after the 4th WD answer -Increment WD failure counter -New WD cycle starts with the same WD question	1b	4 CORRECT or INCORRECT ANSWERS in RESPONSE WINDOW 1
2 CORRECT answers + 2 INCORRECT answers	Not applicable
1 CORRECT answer + 3 INCORRECT answers	Not applicable

(1) WD_QA_ERR is the logical OR of all QA watchdog errors