ARM DS-5 Using the Debug Hardware Configuration Utilities

Creating debug hardware target configurations5.15 Setting the clock speedIt is important to select the best clock speed for your system. Higher clock speeds enable fasterdownloads, but setting the clock speed too high can result in intermittent faults and reliabilityproblems. If you are experiencing such problems, try manually reducing the clock speed. If youare not sure which clock speed to use, try setting the default speed, 10MHz.NoteFor RVI, for reliable operation at high clock speeds you must use the Low Voltage DifferentialSignaling (LVDS) cable.5.15.1 Predefined clock speedTo select a predefined clock speed:1. Select the Devices node in the tree diagram.2. Select the clocking that you want to use from the Clock Speed drop-down list. Thefollowing figure shows an example:Figure 5-12 The scan chain speed controlsNoteAlthough the debug hardware can support JTAG clock speeds down to 13Hz, yourdebugging environment might become unstable at speeds lower than 1kHz.5.15.2 Custom clock speedIf the clock speed you want to use is not available as a preset value, enter the required clockspeed in the Clock Speed field with the Hz, kHz, or MHz suffix as required. For example, 40.0kHz.5.15.3 See alsoTasks• Adding devices to the scan chain on page 5-12• Removing devices from the scan chain on page 5-16• Changing the order of devices on the scan chain on page 5-17.Reference• Device Properties dialog box on page 5-21.ARM DSTREAM System and Interface Design Reference:• Chapter 2 ARM DSTREAM System Design Guidelines.ARM RVI and RVT System and Interface Design Reference:• Chapter 2 RVI and RVT System Design Guidelines.ARM DUI 0498F Copyright © 2010-2012 ARM. All rights reserved. 5-24ID021112Non-Confidential