mc33389 Freescale Semiconductor, Inc, mc33389 Datasheet - Page 25

• Manufacturer Part Number: mc33389
• Description: System Basis Chip With Low Speed Fault Tolerant Can
• Manufacturer: Freescale Semiconductor, Inc

The switches can be directly connected to V
SBC must be properly configured by setting the bit WI2V3 in
the V3 register. In this case, wake-ups are only detected
when V3 is ON. It can take advantage of the V3 Cyclic Sense
feature. If both Cyclic Sense and Forced Wake-Up are
enabled by the SPI in the Sleep mode, only Cyclic Sense will
be active.
Options for Wake Input
up input pins (via SPI in the Wake-Up Input Control Register
(WUICR).
• No Wake-Up— Wake-ups are not detected whatever
• High-State—If the input pin voltage is above the detection
• Low-State—If the input pin voltage is below the detection
• Change of state—Each change of the wake-up input pin is
• Multiple Sampling Events—When wake-up inputs are
two samples High are necessary to validate the wake-up
condition.
Wake-Up Inputs with Permanent Sense
permanent way in Normal and Stand-by modes. If the
contacts are connected to V3, wake-ups are only detected if
V3 is ON.
Analog Integrated Circuit Device Data
Freescale Semiconductor
Different conditions for wake-up can be chosen for wake-
occurs on wake-up inputs.
threshold during more than a 20 µs filter time, a wake-up
is detected. A flag is set in the WUISR.
threshold during more than a 20 µs filter time, a wake-up
is detected. A flag is set in the WUISR.
considered as a wake-up if it lasts more than a 20µs filter
time. The first reference state (no wake-up) is the wake-up
input state when the SBC is programmed to this option. A
flag is set in the WUISR.
used with V3 in Cyclic Sense in the Sleep mode.
For positive edge sensitivity, two samples Low followed by
Wake-up detection can also be accomplished in a
Cyclic Sense connected to wake-up inputs. Example: with wake-up input L1
sensitivity to Low state and timing = 80 ms
Wake-Up
Switch Status
Read L1
V(L1)
INT
V3
1
1
1
OPEN
(t0)
0
0
1
1
BAT
CLOSED
80 ms
Figure 11. Cyclic Sense Timing
or to V3. The
(t1)
0
0
0
160 ms
INT (Wake-Up Active = 0)
Actual State (read)
Memory State
by two samples Low are necessary to validate the wake-up
condition.
followed by two samples in the opposite state are necessary
to validate the wake-up condition.
Wake-Up Inputs with Cyclic Sense
saving because V3 can be programmed to be active, passive,
or cyclic (Cyclic Sense). This provides great flexibility
reducing total power consumption while allowing full wake-up
capabilities. Cyclic Sense is available only in the Sleep mode.
different timings: 32 ms, 64 ms, 128 ms, 256 ms, 512 ms,
1024 ms, 2048 ms, and 8192 ms programmable via SPI in
the CYTCR register. Once activated, V3 remains ON during
400 µs. The wake-up inputs states are sampled at 300 µs.
‘EXCLUSIVE OR’ the forced Wake-Up is chosen (not both).
Sleep mode if the contacts are directly connected to V
they are connected to V3, only Cyclic Sense is available in
Sleep mode).
For negative edge sensitivity, two samples High followed
For both edge sensitivity, two samples at a given state
Connecting the external switches to V3 allows power
The period of the Cyclic Sense can be chosen out of eight
Note: In Sleep mode, the Cyclic Sense feature
Wake-ups are also detected in a permanent way in the
V3
Active
Passive
400 µs
300 µs
Cyclic Sense Programmable Period
Sample Point (80%)
Figure 10. V3 Timing
Wake-Up Inputs Sample Point
300 µs
Setup
400µs
Read
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
BAT
33389
(if
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