ISPPAC-POWR1014A LATTICE [Lattice Semiconductor], ISPPAC-POWR1014A Datasheet - Page 32

• Manufacturer Part Number: ISPPAC-POWR1014A
• Description: In-System Programmable Power Supply Supervisor, Reset Generator and Sequencing Controller
• Manufacturer: LATTICE [Lattice Semiconductor]

Lattice Semiconductor
Three special purpose pins, VCCPROG, ATDI and TDISEL, enable programming of the un-programmed ispPAC-
POWR1014/A under such circumstances. The VCCPROG pin powers just the programming circuitry of the ispPAC-
POWR1014/A device. The ATDI pin provides an alternate connection to the JTAG header while bypassing all the
un-powered devices in the JTAG chain. TDISEL pin enables switching between the ATDI and the standard JTAG
signal TDI. When the internally pulled-up TDISEL = 1, standard TDI pin is enabled and when the TDISEL = 0, ATDI
is enabled.
In order to use this feature the JTAG signals of the ispPAC-POWR1014/A are connected to the header as shown in
Figure 26. Note: The ispPAC-POWR1014/A should be the last device in the JTAG chain.
Figure 26. ispPAC-POWR1014/A Alternate TDI Configuration Diagram
Alternate TDI Selection Via JTAG Command
When the TDISEL pin held high and four consecutive IDCODE instructions are issued, ispPAC-POWR1014/A
responds by making its active JTAG data input the ATDI pin. When ATDI is selected, data on its TDI pin is ignored
until the JTAG state machine returns to the Test-Logic-Reset state.
This method of selecting ATDI takes advantage of the fact that a JTAG device with an IDCODE register will auto-
matically load its unique IDCODE instruction into the Instruction Register after a Test-Logic-Reset. This JTAG capa-
bility permits blind interrogation of devices so that their location in a serial chain can be identified without having to
know anything about them in advance. A blind interrogation can be made using only the TMS and TCLK control
pins, which means TDI and TDO are not required for performing the operation. Figure 27 illustrates the logic for
selecting whether the TDI or ATDI pin is the active data input to ispPAC-POWR1014/A.
TDISEL
TMS
TDO
TCK
TDI
JTAG Signal
Connector
TDI
3. Sequenced Power
Supply Turn-on
Other JTAG
Device(s)
TDO
32
Supply Turn-On
2. Initial Power
ATDI
TDI
ispPAC-POWR1014/A Data Sheet
ispPAC-POWR
1014A
Programming
POWR1014A
1. Power for
TDO