TSS463C ATMEL Corporation, TSS463C Datasheet - Page 22

• Manufacturer Part Number: TSS463C
• Description: Van Data Link Controller With Serial Interface
• Manufacturer: ATMEL Corporation

Diagnosis System
Diagnosis States
Figure 21. Diagnosis States
22
TSS463C
Degraded
Data
- Failure during the frame.
- Default of transitions on the valid input between 2 consecutive SDC rising edges.
- Protocol fault
- In specified selection mode, every RI pulse when an EOF is detected or through an active SDC.
- In automatic selection mode and SDC active, no failure sampled by 2 consecutive SDC rising edges.
- General reset.
The purpose of the diagnosis system is to detect any short or open circuits on either the
DATA or DATA lines and to permit, if it is possible, to carry the communications on the
non-defective line.
The diagnosis system is based on the assumption that three separate line receivers are
connected to the VAN bus see Figure 1.
•
•
The diagnosis system analyzes and compares the data sent over both VAN lines. So,
the diagnosis system executes a digital filtering and transition analyses. In order to per-
form its investigation, three internal signals are generated, RI (Return to Idle), SDC
(Synchronous Diagnosis Clock) and TIP (Transmission In Progress).
One of four operating modes can be chosen to manage the results of the diagnosis
system.
If the diagnosis system finds a failure on any of the VAN bus signals, it changes from
nominal to degraded mode, and connects the line receiver not coupled to the failing sig-
nal to the reception logic.
When the diagnosis system finds that the failing signal is working again, it returns to
nominal mode and re-connects the differential line receiver to the reception logic.
A major error occurs when both the VAN bus signals are failed.
One of the line receivers is connected in differential mode, sensing both DATA and
DATA signals, and is connected to the RxD0 input.
The other two line receivers are operating in single wire mode and are sensing only
one of the two VAN bus signals:
–
–
The line receiver sensing DATA is connected to RxD1
The line receiver sensing DATA is connected to RxD2
Nominal
Major
Error
Degraded
Data
7601B–AUTO–02/06