ETAS
Hardware Description
XETK-S22.0 - User’s Guide
25
4.9
XETK-S22.0B: JTAG Interface
Fig. 4-8
Equivalent Circuitry of the ECU JTAG Interface (ECU)
The ECU part of the JTAG XETK interface is depicted in Fig. 4-8.
The XETK-S22.0 incorporates 22 Ohm series resistors for the TMS, TCK, TDI
and /TRST lines on the ECU interface. Hence, no additional termination resis-
tors are required on the ECU for these signals.
Additional Design Recommendations:
• Debug connector should be placed as close to the microcontroller as
possible
• If a pull down resistor is present on the line /TRST, the ECU must use a
value no smaller than 100K ohm as shown in Fig. 4-8 on page 25.
• PCB trace lengths should be as short as possible for the TMS, TRST,
TCK, TDI & TDO signals
• If any JTAG signals are also routed to a 2nd connector (Forked/Split or
T’d), It is recommended to add zero ohm jumpers in line so the signal T
can be broken
• ETAN1/4/6 cables are 50 ohm impedance for all signals, it is recom-
mended to match the PCB impedance to the cable impedance
ETAN1/4/6
ETAM2/5/9
/TRST
TMS
/ RES_IN
>
=10
0k
VDDPSTBY
(ECU
interface)
GND
VDDSTBY
(ERAM)
CAL
Wakeup
RH850
TDO
/TRST
FLMD0
TCK
TDI
TDO
GND
TMS
/ PORST
VDD
(Sense)
RDY
TCK
/RES_OUT
1
2
11
12
EMU
VDD
TDI
/DRDY
1.
XETK:
supply
and
monitor
the
voltage
of
the
ERAM
R
XE
T
K
=
0
R
EC
U
=
0
2.
ECU:
supply
the
voltage
of
the
ERAM
OR
Permanent
Power
supply
(External
supply
of
UBATT,
if
not
available
internal))
UBATT1
Power
supply
of
the
ERAM:
Option
1:
provided
by
XETK
Option
2:
provided
by
ECU
ECU
/RSTOUT
VSTBY
MD0
UBATT2
6
Notes:
‐
ETAM9
does
not
provide
pin
6
‐
ECU
connection
is
5
pin
Molex
or
solder
points
Permanent
Power
supply
(Internal
UBATT,
else
internal
ignition)
1
If
a
pull
down
is
present,
it
must
be
>=
100k
XETK
‐
S22.0B
