XETK-V2.0 - User’s Guide
38
ETAS
Hardware Description
The required circuitry for the trigger lines DAI1 and DAI2 on the ECU is shown in
Fig. 4-16 "Equivalent Circuitry of the XETK-V2.0A/C DAI Interface via VertiCal
(BGA)",Fig. 4-17 "Equivalent Circuitry of the XETK-V2.0A/C DAI Interface via
VertiCal (QFP)", and Fig. 4-18 "Equivalent Circuitry of the XETK-V2.0B DAI Inter-
face". The two hardware triggers are active low signals.
Interrupt lines DAI1 and DAI2 are also used for startup communication, see
chapter 4.11.4 on page 36.
4.12
Pinless Startup and Triggering
The XETK-V2.0 also offers a pinless mechanism for the startup handshake and
triggering. This mechanism is only available with certain microcontrollers. Pinless
refers to the concept that no additional microcontroller GPIO pins are required
for triggering. Instead, built in microcontroller registers and a dedicated Nexus
signal, /EVTO, are utilized.
The XETK-V2.0 can use the pinless startup and triggering mechanism with the
MPC5676R, MPC5644A, SPC564A80, and MPC5777C.
4.12.1
Startup Handshake
During reset the microcontroller registers are initialized to reset values:
DTS_SEMAPHORE is 0xFFFFFFFF, DTS_STARTUP is 0x00000000, and the DTS_EN
bit of DTS_ENABLE is 0.
When the reset is deactivated the XETK enables the link between the
DTS_SEMAPHORE register and the signal /EVTO by setting the DTS_EN bit to 1.
The /EVTO signal goes low and the XETK reads the DTS_SEMAPHORE, this regis-
ter automatically clears to 0x00000000 after being read.
A special pattern is then written to the DTS_STARTUP register by the XETK. This
pattern includes the standby RAM power fail status of the ECU/XETK. (No power
fail: 0x0000000A is written, Power fail: 0x00000009 is written). In case the XETK
or the RAM being monitored by the XETK looses power then the Power fail pat-
tern will be written. This pattern indicates to the ECU that the working page data
is invalid and should not be used. If the working page was previously initialized,
the XETK and the RAM being monitored by the XETK remain powered, the No
power fail pattern will be written. This pattern indicates to the ECU that the
working page data is still valid and may be used.
The DTS_STARTUP register is written to by the XETK within 500 microseconds
after the microcontroller is out of reset.
Application running
The ECU software detects the connected XETK by reading the DTS_STARTUP
register. Thereafter the ECU software performs basic initilizations and when fin-
ished writes 0x55555555 to the DTS_SEMAPHORE register. The XETK is notified
of the write by the /EVTO signal, reads the DTS_SEMAPHORE register and com-
Note
Note