TSS461 ATMEL Corporation, TSS461 Datasheet - Page 20

• Manufacturer Part Number: TSS461
• Description: VAN Data Link Controller
• Manufacturer: ATMEL Corporation

Internal
Operations
Digital Filtering
Transition Analyses
20
TSS461E
Table 3. Status Bits Sa and Sb
Notes:
If several spurious pulses occur during one bit, the diagnosis for defective conductor may be
corrupted. To avoid such errors, digital filters are implemented.
Filtering operation is based on sampling of the comparator output signals. A transition is taken
into account only if it is observed over five samples (1/16th of timeslot).
These analyses are continuously done on the effective edges on comparators after digital
filtering.
•
•
•
Asynchronous diagnosis:
The asynchronous diagnosis is done by comparing the number of edges on DATA and
DATA.
If four edges are detected on one input and no edges on the other during the same period,
the second input is considered faulty and the diagnosis mode will change to one of the
degraded modes.
Synchronous diagnosis:
The synchronous diagnosis counts the number of edges on the data input connected to the
reception logic during one SDC period.
If there are less than four edges during one SDC period, the diagnosis mode will change to
the major error mode.
Transmission diagnosis:
The transmission compares RxD1 and RxD2 inputs (through the input comparators and the
1. Sc bit sets to 1 as soon as one of the three inputs (RXD2, RXD1, RXD0) differs from the others
2. The only way to reset this status bit is through the RI signal or a general reset.
in the input comparison analysis performed by the diagnosis system, S2 is set.
Sa
0
0
1
1
Sb
0
1
0
1
Mode
Fault
Status
Mode
Fault
Status
Mode
Fault
Status
Mode
Fault
Status
Communication
nominal
no fault on VAN bus
differential communication DATA and DATA
degraded on DATA
fault on DATA
communication on DATA
degraded on DATA
fault on DATA
communication on DATA
major error
fault on DATA and DATA
no communication on DATA and DATA (attempt to
communicate alternatively on DATA then
SDC period.
4194C–AUTO–01/06
DATA
every