Xilinx Virtex-4 - Resuming Configuration or Readback after an Abort; Selectmap Reconfiguration

Virtex-4 FPGA Configuration User Guide www.xilinx.com 51
UG071 (v1.12) June 2, 2017
SelectMAP Configuration Interface
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The ABORT sequence lasts four CCLK cycles. During those cycles, the status word changes
to reflect data alignment and ABORT status. A typical sequence might be:
11011111 => DALIGN = 1, IN_ABORT_B = 1
11001111 => DALIGN = 1, IN_ABORT_B = 0
10001111 => DALIGN = 0, IN_ABORT_B = 0
10011111 => DALIGN = 0, IN_ABORT_B = 1
After the last cycle, the synchronization word can be reloaded to establish data alignment.
Resuming Configuration or Readback After an Abort
There are two ways to resume configuration or readback after an ABORT:
• The device can be resynchronized after the ABORT completes.
• The device can be reset by pulsing PROGRAM_B Low at any time.
To resynchronize the device, CS_B must be deasserted, then reasserted. The configuration
synchronization word can then be sent. Configuration or readback can be resumed by
sending the last configuration or readback packet that was in progress when the ABORT
occurred. Alternatively, configuration or readback can be restarted from the beginning.
SelectMAP Reconfiguration
The term reconfiguration refers to reprogramming an FPGA after its DONE pin has gone
High. Reconfiguration can be initiated by pulsing the PROGRAM_B pin (this method is
identical to configuration), or by resynchronizing the device and sending configuration
data. The latter method is only available in SelectMAP and JTAG configuration modes.
To reconfigure a device in SelectMAP mode without pulsing PROGRAM_B, the BitGen
persist option must be set—otherwise, the SelectMAP data pins become user I/O after
configuration. Reconfiguration must be enabled in BitGen. The SelectMAP port width is
either 8 or 32 bits as selected by the mode pin settings.
Reconfiguration begins when the synchronization word is clocked into the SelectMAP
port. The remainder of the operation is identical to configuration as described above.
Table 2-5: ABORT Status Word
Bit Number Status Bit Name Meaning
D7 CFGERR_B
Configuration error (active Low)
0 = A configuration error has occurred.
1 = No configuration error.
D6 DALIGN
Sync word received (active High)
0 = No sync word received.
1 = Sync word received by interface logic.
D5 RIP
Readback in progress (active High)
0 = No readback in progress.
1 = A readback is in progress.
D4 IN_ABORT_B
ABORT in progress (active Low)
0 = Abort is in progress.
1 = No abort in progress.
D3-D0 1111