RDWR_B is an input to the
FPGA that controls whether the data pins are inputs or outputs:
- If
RDWR_B=0, the data pins are inputs (writing to the FPGA). - If
RDWR_B=1, the data pins are outputs (reading from the FPGA).
For configuration, RDWR_B
must be set for write control (RDWR_B = 0). For readback, RDWR_B
must be set for read control (RDWR_B = 1) while CSI_B is
asserted.
3D ICs do not support the ABORT sequence.
In monolithic devices, changing the value of RDWR_B from
Low to High while CSI_B is Low triggers an ABORT, and the
configuration I/O changes from input to output asynchronously. The ABORT
status appears on the data pins synchronously. Changing the value of
RDWR_B from High to Low while
CSI_B is Low also triggers an ABORT, and the
configuration I/O changes from output to input asynchronously with no ABORT
status readback. If readback is not needed, RDWR_B can be
tied to ground or used for debugging with SelectMAP ABORT.
The RDWR_B signal is
ignored while CSI_B is de-asserted. Read/write control of
the 3-stating of the data pins is asynchronous. The FPGA actively drives
SelectMAP data without regard to CCLK if
RDWR_B is set for read control
(RDWR_B = 1,
Readback) while CSI_B is asserted.