DS1036 - Platform Manager Data Sheet - Lattice Semiconductor

Figure 49. Platform Manager JTAG Interconnection Configuration Diagram
APS
TMS
TDO
TDI
TCK
TDISEL
Board
3.3V
To Other Board
Devices
Programming Platform Manager: Alternate Method
66
Platform Manager Data Sheet
Some applications require that the Platform Manager be programmed before turning the power on to the entire circuit
board. To meet such application needs, the Platform Manager provides an alternate programming method
which enables the programming of the Platform Manager device through the JTAG chain with a separate power
supply applied just to the programming section of the Platform Manager device with the main power supply of the
board turned off.
Three special purpose pins, APS, PATDI and PTDISEL, enable programming of the un-programmed Platform Manager
under such circumstances. The APS pin provides power to the programming circuitry of the Platform Manager
device (when PVCCD and PVCCA are unpowered). The PVCCJ pin must be powered to enable the JTAG port.
The PATDI pin provides an alternate connection to the JTAG header while bypassing all the un-powered devices in
the JTAG chain. PTDISEL pin enables switching between the PATDI and the standard JTAG signal PTDI. When the
internally pulled-up PTDISEL = 1, standard PTDI pin is enabled and when the PTDISEL = 0, PATDI is enabled.
In order to use this feature the JTAG signals of the Platform Manager are connected to the header as shown in
Figure 50. Note: The Platform Manager should be the last device in the JTAG chain.
After programming, the APS pin MUST be left floating when the PVCCD and PVCCA pins are powered.
Alternate PTDI Selection Via JTAG Command
FTCK
Other
VCC
FTDO
FTDI
FTMS
VCCIO2
Platform Manager
When the PTDISEL pin held high and four consecutive IDCODE instructions are issued, Platform Manager
responds by making its active JTAG data input the PATDI pin. When PATDI is selected, data on its PTDI pin is
ignored until the JTAG state machine returns to the Test-Logic-Reset state.
This method of selecting PATDI takes advantage of the fact that a JTAG device with an IDCODE register will automatically
load its unique IDCODE instruction into the Instruction Register after a Test-Logic-Reset. This JTAG
capability 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 PTMS and PTCK
control pins, which means PTDI and PTDO are not required for performing the operation. Figure 50 illustrates the
logic for selecting whether the PTDI or PATDI pin is the active data input to Platform Manager.
PTCK
APS
PTDI
PVCCA/D
PTDO
PVCCJ
PTMS
PATDI
PTDISEL
From Other Board
Devices