ETK-S6.0 - User’s Guide
26
ETAS
Hardware Description
Successive phases of the startup protocol
1.
Reset phase:
The ECU is in reset, the DAI ports are configured as inputs.
The ETK pulls DAI1 and DAI2 weakly high (via 33 kOhm pullup resistors).
2.
ECU Initialization phase:
The ECU performs internal initializations, the
DAI ports are still inputs. The ETK pulls DAI1 low via 3k3 kOhm, DAI2 is
pulled either weakly high (via the 33 kOhm pullup resistor) or low (via
3k3 kOhm).
3.
Initialization of ECU resources by ETK:
The ECU configures the DAI
ports as outputs and drives a logical high to signal the transition from
phase 2 to phase 3. Then the ETK removes any pulldown resistors and
starts initialization of the ECU resources.
4.
Calibration and data acquisition:
The ECU pulls the appropriate DAI
port low to signal a trigger condition to the ETK, i.e. a measurement raster
is ready for acquisition.
ECU and ETK Reset Detection Levels
There are different reset detection levels of ECU and ETK with resulting uncer-
tainty t
1
.
Fig. 4-12
Startup Procedure in Detail
The condition for proper operation is:
t
1
+ t
HOLD
<< t
2
<< t
3
Reset
DAI1
DAI2
t
1
t
ECU reset detection level
ETK reset detect ion level
t
2
t
3
t
t
