32186 datasheet(900/1032 Pages) RENESAS

900 / 1032 page

JTAG

21-6

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

21.4 Basic Operation of JTAG

21.4.1 Outline of JTAG Operation

The instruction and data registers basically are accessed in conjunction with the following three opera-

tions, which are performed based on the TAP Controller’s state transition. The TAP Controller changes

state according to JTMS input, and generates control signals required for operation in each state.

• Capture operation

The result of boundary-scan test or the fixed data defined for each register is sampled. As a register

operation, data input is latched into the shift register stage.

• Shift operation

The register is accessed from outside through the boundary-scan path. The sample value is output to

the outside at the same time data is set from the outside. As a register operation, the bits are shifted

right between each shift register stage.

• Update operation

The data set from the outside during shifting is driven. As a register operation, the value set in the shift

The JTAG interface undergoes transition of the internal state depending on JTMS input and on such

state transition, it performs the following two operations. In either case, the operation basically is

performed in order of Capture

→ Shift → Update.

• IR path sequence

Instruction code is set in the instruction register to select the data register to be operated on in the

subsequent DR path sequence.

• DR path sequence

Data inspection or setting is performed for the selected data register.

21.4 Basic Operation of JTAG

32186 Datasheet(PDF) 900 Page - Renesas Technology Corp