88F6281

Hardware Specifications

7.3Bypass Register

The Bypass register (BR) is a single bit serial shift register that connects TDI to TDO, when the IR holds the Bypass command, and the TAP FSM is in Shift-DRstate. Data that is driven on the TDI input pin is shifted out one cycle later on the TDO output pin. The Bypass register is loaded with 0 when the TAP FSM is in the Capture-DRstate.

7.4JTAG Scan Chain

The JTAG Scan Chain is a serial shift register used to sample and drive all of the device pins during the JTAG tests. It is a 2-bit per pin shift register in the device, thereby allowing the shift register to sequentially access all of the data pins both for driving and strobing data. For further details, refer to the BSDL Description file for the device.

7.5ID Register

The ID register is a 32-bit deep serial shift register. The ID register is loaded with vendor and device information when the TAP FSM is in the Capture-DRstate. The Identification code format of the ID register is shown in Table 34, which describes the various ID Code fields.

Table 34: IDCODE Register Map

Bits

Value

Description

31:28

0x0

Version (4'b0010 for version A0, 4'b0011 for A1, etc.)

27:12

0x6281

Part number

 

 

 

11:1

0x1AB

Manufacturer ID

0

1

Mandatory

 

 

 

Doc. No. MV-S104859-U0 Rev. E

 

Copyright © 2008 Marvell

Page 74

Document Classification: Proprietary Information

December 2, 2008, Preliminary

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Image 74
Marvel Group 88F6281 Bypass Register, Jtag Scan Chain, ID Register, Idcode Register Map, Bits Value Description