Intel IXP45X, IXP46X manual 3.13JTAG Interface, 3.12.5Design Notes

General Hardware Design Considerations—Intel®IXP45X and Intel® IXP46X Product Line of Network Processors

Table 21.	PCI Host/Option Interface Pin Description (Sheet 3 of 3)
		Host		Option
Name		Input	Device-Pin Connection	Input	Description
		Outpu		Outpu
		t		t
			Connect PCI_INTA_N output from the		Interrupt A
PCI_INTA_N		O/D	Option to one of the GPIO input signals		This interrupt is generated from the Option to
			of the Host. The GPIO signal at the	O/D	one of the GPIO inputs to the Host.
			Host must be configure as an input		On the Host this signal is not used, it should
			interrupt level sensitive.		be pulled high with a 10-KΩresistor.
			Clock must be connected to both
PCI_CLKIN		I	devices. Trace lengths must be	I	Clock input
			matched. Use point to point clock
			distribution.

3.12.5Design Notes

•The IXP45X/IXP46X network processors do not support the 5 V PCI signal interface by itself. Only the 3.3 V signal interface is supported without signal level conversion, however, it is possible to interface to 5 V logic when using a voltage level converter. See Figure 17 for details.

•The PCI Local Bus Specification, Rev. 2.2 requires that the bus is always “parked”, as some device is always driving the AD lines. There is need to use pull-ups on these signals. The specification states that the following control lines should be pulled up:

— FRAME#	— TRDY#	— IRDY#	— DEVSEL#
— STOP#	— SERR#	— PERR#	— LOCK#
— INTA#	— INTB#	— INTC#	— INTD#

•The processors’ GPIO pins can be used by PCI devices on PCI slots to request an interrupt from the processors’ PCI controller.

•PCI_INTA_N is used to request interrupts to external PCI Masters. This signal is an open collector and requires a pull-up resistor.

3.13JTAG Interface

JTAG is the popular name for IEEE standards 1149.1-1990 and 1149.1a-1993, IEEE Standard Test Access Port and Boundary-Scan Architecture, which provides support for:

•Board-level boundary-scan connectivity testing

•Connection to software debugging tools through the JTAG interface

•In-system programming of programmable memory and logic devices on the PCB

The interface is controlled through five dedicated test access port (TAP) pins: TDI, TMS, TCK, nTRST, and TDO, as described in the IEEE 1149.1 standard. The boundary-scan test-logic elements include the TAP pins, TAP controller, instruction register, boundary- scan register, bypass register, device identification register, and data-specific registers. These are described in the Intel® IXP45X and Intel® IXP46X Product Line of Network Processors Developer’s Manual.

The IXP45X/IXP46X network processors may be controlled during debug through a JTAG interface to the processor, the debug tools such as the Macraigor* Raven*, EPI* Majic*, Wind River Systems* visionPROBE* / visionICE* or various other JTAG tools plug into the JTAG interface through a connector.

	Intel® IXP45X and Intel® IXP46X Product Line of Network Processors
February 2007	HDD
Document Number: 305261; Revision: 004	53