debugging process. All important functions which are used by
the SEGGER software are useable via the USB protocol.
J-Link ARM has many features:
USB 2.0 interface
Any ARM7/ARM9 core supported, including thumb mode
Automatic core recognition
Maximum JTAG speed 12 MHz
Download speed up to 720 Kbytes/second *
DCC speed up to 800 Kbytes/second *
No power supply required, powered through USB
Auto speed recognition
Support for adaptive clocking
All JTAG signals can be monitored, target voltage can be measured
Support for multiple devices
Fully plug and play compatible
A Standard 20-pin JTAG connector
Optional 14-pin JTAG adapter available
Wide target voltage range: 1.2V - 3.3V
Optional adapter for 5V targets available
Measured with J-Link Rev.5, ARM7 @ 50 MHz, 12MHz JTAG speed.
What you may do
You may use the information contained in this document to add support for the wide
spread SEGGER J-Link ARM emulator and OEM versions in open source software.
What you are not allowed to do
You are not allowed to use the information in this document to
build J-Link clones
build J-Link compatible emulators.
Some JTAG-related commands need an IRpre and DevicePos parameter. These values
describe the position of a device in the scan chain and the shift count to reach that
device.
The diagram below shows a scan chain configuration sample with 2 devices connected
to the JTAG port.
The IRPre value is the total number of bits in the instruction registers of the devices
before the DUT counted from nearest device to TDO. The position can usually be seen
in the schematic; the IR len can be found in the manual supplied by the manufacturers
of the other devices.
ARM7 and ARM9 have an IR len of four.
For systems with just a single device, IRPre is 0.
For an example using the IRpre value please refer to the paragraph Scan chain exam-
ple on page 15.
To buy J-link v8,please visit www.obd2works.com
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