uja1061 NXP Semiconductors, uja1061 Datasheet - Page 13

• Manufacturer Part Number: uja1061
• Description: Low Speed Can/lin System Basis Chip
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UJA1061_5
Product data sheet
6.4.1 Watchdog start-up behavior
6.4.2 Watchdog window behavior
Any microcontroller driven mode change is synchronized with a watchdog access by
reading the mode information and the watchdog period information from the same
register. This enables an easy software flow control with defined watchdog behavior when
switching between different software modules.
Following any reset event the watchdog is used to monitor the ECU start-up procedure. It
observes the behavior of the RSTN pin for any clamping condition or interrupted reset
wire. In case the watchdog is not properly served within t
and the monitoring procedure is restarted. In case the watchdog is again not properly
served, the system enters Fail-safe mode (see also
Whenever the SBC enters Normal mode, the Window mode of the watchdog is activated.
This ensures that the microcontroller operates within the required speed; a too fast as well
as a too slow operation will be detected. Watchdog triggering using the Window mode is
illustrated in
The SBC provides 10 different period timings, scalable with a 4 factor watchdog prescaler.
The period can be changed within any valid trigger window. Whenever the watchdog is
triggered within the window time, the timer will be reset to start a new period.
Fig 4. Watchdog triggering using Window mode
•
•
Illegal watchdog period coding; only ten different codes are valid
Illegal operating mode coding; only six different codes are valid
trigger
via SPI
Figure
trigger point
last
4.
Rev. 05 — 22 November 2007
trigger
restarts
period
too early
(with different duration if
trigger restarts period
earliest possible
Fault-tolerant CAN/LIN fail-safe system basis chip
trigger point
period
50 %
desired)
trigger
via SPI
trigger window
Figure
too early
latest possible
trigger point
WD(init)
100 %
new period
possible
earliest
3, Start-up and Restart mode).
trigger
50 %
point
, another reset is forced
window
trigger
© NXP B.V. 2007 Nov 23. All rights reserved.
possible
trigger
latest
100 %
point
UJA1061
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