ISPPAC30-01SI LATTICE [Lattice Semiconductor], ISPPAC30-01SI Datasheet - Page 26

• Manufacturer Part Number: ISPPAC30-01SI
• Description: In-System Programmable Analog Circuit
• Manufacturer: LATTICE [Lattice Semiconductor]

Lattice Semiconductor
TAP Controller Specifics
The TAP is controlled by the Test Clock (TCK) and Test Mode Select (TMS) inputs. These inputs determine whether
an Instruction Register or Data Register operation is performed. Driven by the TCK input, the TAP consists of a
small 16-state controller design. In a given state, the controller responds according to the level on the TMS input as
shown in Figure 10. Test Data In (TDI) and TMS are latched on the rising edge of TCK, with Test Data Out (TDO)
becoming valid on the falling edge of TCK. There are six steady states within the controller: Test-Logic-Reset, Run-
Test/Idle, Shift-Data-Register, Pause-Data-Register, Shift-Instruction-Register and Pause-Instruction-Register. But
there is only one steady state for the condition when TMS is set high: the Test-Logic-Reset state. This allows a
reset of the test logic within five TCKs or less by keeping the TMS input high. Test-Logic-Reset is the power-on
default state.
Figure 10. TAP States
When the correct logic sequence is applied to the TMS and TCK inputs, the TAP will exit the Test-Logic-Reset state
and move to the desired state. The next state after Test-Logic-Reset is Run-Test/Idle. Until a data or instruction shift
is performed, no action will occur in Run-Test/Idle (steady state = idle). After Run-Test/Idle, either a data or instruc-
tion shift is performed. The states of the Data and Instruction Register blocks are identical to each other differing
only in their entry points. When either block is entered, the first action is a capture operation. For the Data Regis-
ters, the Capture-DR state is very simple: it captures (parallel loads) data onto the selected serial data path (previ-
ously chosen with the appropriate instruction). For the Instruction Register, the Capture-IR state will always load
the IDCODE instruction. It will always enable the ID Register for readout if no other instruction is loaded prior to a
Shift-DR operation. This, in conjunction with mandated bit codes, allows a “blind” interrogation of any device in a
compliant IEEE 1149.1 serial chain.
From the Capture state, the TAP transitions to either the Shift or Exit1 state. Normally the Shift state follows the
Capture state so that test data or status information can be shifted out or new data shifted in. Following the Shift
state, the TAP either returns to the Run-Test/Idle state via the Exit1 and Update states or enters the Pause state via
Exit1. The Pause state is used to temporarily suspend the shifting of data through either the Data or Instruction
Register while an external operation is performed. From the Pause state, shifting can resume by reentering the
Shift state via the Exit2 state or be terminated by entering the Run-Test/Idle state via the Exit2 and Update states.
If the proper instruction is shifted in during a Shift-IR operation, the next entry into Run-Test/Idle initiates the test
mode (steady state = test). This is when the device is actually programmed, erased or verified. All other instructions
are executed in the Update state.
0
1
Test-Logic-Rst
Run-Test/Idle
Note: The value shown adjacent to each state transition in this figure
represents the signal present at TMS at the time of a rising edge at TCK.
0
1
1
0
Select-DR-Scan
1
Capture-DR
Update-DR
Pause-DR
Exit1-DR
Exit2-DR
Shift-DR
26
0
0
1
0
1
1
0
1
1
0
0
ispPAC30 Preliminary Data Sheet
1
0
Select-IR-Scan
1
Capture-IR
Update-IR
Pause-IR
Exit1-IR
Exit2-IR
Shift-IR
0
0
1
0
1
1
0
1
1
0
0