pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 256

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

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Embedded Controller Modules
TAP Controller Operation
The TAP controller changes state only in response to the following events:
The TAP controller generates signals to control the operation of the TAP registers and associated PC87591x reset, ISE in-
terrupt control and data link circuitry.
The TDO output buffer and the circuitry that selects the register output fed to TDO are controlled as shown in Table 37.
Changes at TDO, as defined in Table 37, occur on the falling edge of TCK after entry into the state.
TAP Controller Initialization
Circuitry built into the PC87591x forces the TAP controller into TAP-Reset state at power-up in an asynchronous manner.
The TAP controller must not be initialized by operation of any system input, such as a system reset.
When TMS is equal to 1 for five consecutive TCK cycles, this forces the controller into TAP-Reset state from any state.
4.19.6 TAP Instruction Register
The Instruction Register (IR) allows an instruction to be shifted into the Debugger interface. The instruction selects the mode
of operation, the data register to be addressed or both.
In any serial scan operation, the JTAG serial bus controller transmits and receive vectors of the same length. This serial
scan chain property is used to transmit status bits from the device to the bus controller in any instruction scan operation. The
Instruction register in the PC87591x allows status information generated within the data links to be examined and supports
flash programing, as shown in Table 38 on page 257.
Design and Construction
The IR uses a shift register-based design with a parallel input for register cells other than the two nearest to the serial output.
An instruction, shifted into the register, is latched at the completion of the shifting process.
The IR includes 12 shift register-based cells capable of holding instruction data.
An instruction that is shifted into the register is latched so that the related changes occur only in the Update IR and TAP-
Reset states.
A rising edge of TCK
Power-up
Controller State
Select-DR-Scan
Select-IR-Scan
Run-Test-Idle
Capture-DR
Update-DR
Capture-IR
Tap-Reset
Update-IR
Pause-DR
Pause-IR
Exit2-DR
Shift-DR
Exit1-IR
Exit2-IR
Exit-DR
Shift-IR
Table 37. TAP Operation in Each Controller State
Register Selected to Drive TDO
(Continued)
Undefined
Undefined
Undefined
Undefined
Undefined
Instruction
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Test Data
256
TDO Driver Level
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Active
Active
Revision 1.07