GT-64260A Design Guide
Doc. No. MV-S300165-00, Rev. A
CONFIDENTIAL
Copyright © 2002 Marvell
Page 78
Document Classification: Proprietary Information
May 21, 2002, Preliminary
Section 9. JTAG Interface Functional Overview
The GT-64260A JTAG interface is compliant with the Boundary-Scan standard known as IEEE 1149.1.
The following JTAG commands are supported by the GT-64260A JTAG TAP controller:
•
EXTEST (0000)
•
SAMPLE (0001)
•
BYPASS (1111)
•
HIGHZ (0011)
•
IDCODE (0010)
•
TEST (0100)
The GT-64260A IDCODE value is 0x12300157, see the BSDL file at Marvell secured web site,
http://www.galileot.com/secure/products/discovery/#BSDL MODELS
.
If the current instruction is IDCODE in the GT-64260A TAP controller implementation, each exit from the SHIFT-
DR state will cause the IDCODE to be fetched to DR (all 32 bits). While the controller is in the SHIFT-DR state, it
shifts data from TDI to the register and, after the IDCODE was shifted out from the TDO, it starts shifting out that
data.
It is recommended to use the BYPASS instruction to shift the data from TDI to TDO. This requires fewer shifting
cycles.
Note
See the IEEE 1149.1 specification for details on JTAG operation.