TASKING iSYSTEM ST SPC58 Hardware User Manual page 13

J6 and J7: RTC Clock source
Jumpers J6 and J7 select the RTC Clock source (32,768 kHz XTAL) for the emulation device. Per
default, both jumpers are set to position 1-2, which yields the clock source being used from the
target.
If an oscillator in the target is not an option and the target crystal doesn't oscillate in conjunc-
tion with the EA, the EA can also provide the clock source (XTAL) by setting jumpers J6 and J7
in position 2-3. In this case, a crystal circuit must be built on the EA.
Note that the Emulation Adapter may not operate when crystal circuit is used in the
target. Typical design guideline is that the crystal should be as close as possible to the
microcontroller.
It can happen that the target crystal does not oscillate in conjunction with the Emula-
tion Adapter since clock lines (XTAL, EXTAL) between the target crystal and the emula-
tion device on the Emulation Adapter become too long, inevitably too much affecting
the impedance of the crystal circuit. If a "standalone" oscillator is used instead of the
crystal circuit, no problems are expected.