Configuring The Emulation Probe For Maximum Performance; Setting Tck Speed; When To Decrease Tck Speed; When To Increase Tck Speed - Agilent Technologies E5900B User Manual

Configuring the Emulation Probe

Configuring the Emulation Probe for Maximum Performance

Configuring the Emulation Probe for Maximum
Performance
The performance of the emulation probe depends on the speed at which it
communicates with the target system. Better performance is obtained with
faster communication speeds.

Setting TCK speed

On JTAG debug ports the communication speed is controlled by the clock
signal TCK. This signal is generated by the emulation probe. You can set the
speed of TCK using the Emulation Control Interface in a 16700-series logic
analysis system or by using the cf speed command through a telnet or
debugger connection to the emulation probe.
To change TCK speed, send a cf speed=x command to the probe. To
restore default, send an init -c command. For more information about cf
speed, send a help cf speed command to the probe. Also note that some
debuggers allow the speed to be set from within their GUI or from a command
file.

When to decrease TCK speed

Emulation probes are configured at the factory with a default TCK speed. In
most cases, this is equal to the maximum allowable speed as specified by the
manufacturer (see the table). This speed is suitable for most applications.
However, this speed is only valid if 1) the processor is running at it's full rated
speed, 2) trace lengths from the processor to the JTAG connector are short
(two inches or less), and 3) there are no stubs on the JTAG signals. If the
emulation probe cannot communicate reliably with the target system using
the factory default speed, TCK speed must be reduced.

When to increase TCK speed

Some target systems will allow TCK speeds greater than the default. The real
maximum speed for a given target system can be determined empirically by
increasing the speed and observing if the communication to the target is
reliable. However, please note that speeds greater than the default are not
officially supported by Agilent or the chip manufacturer.
70 Emulation for the Motorola M•CORE