User guide
Spartan-6 FPGA Configuration User Guide www.xilinx.com 37
UG380 (v2.7) October 29, 2014
SelectMAP Configuration Interface
Notes relevant to Figure 2-8:
1. CSI_B signal can be tied Low if there is only one device on the SelectMAP bus. If CSI_B
is not tied Low, it can be asserted at any time.
2. RDWR_B can be tied Low if readback is not needed. RDWR_B should not be toggled
after CSI_B has been asserted because this triggers an ABORT. See SelectMAP ABORT,
page 153.
3. The Mode pins are sampled when INIT_B goes High.
4. RDWR_B should be asserted before CSI_B to avoid causing an abort.
5. CSI_B is asserted, enabling the SelectMAP interface.
6. The first byte is loaded on the first rising CCLK edge after CSI_B is asserted.
7. The configuration bitstream is loaded one byte per rising CCLK edge.
8. After the startup command is loaded, the device enters the startup sequence.
9. The startup sequence lasts a minimum of eight CCLK cycles (see Startup (Step 8) in
Chapter 5).
10. The DONE pin goes High during the startup sequence. Additional CCLKs can be
required to complete the startup sequence. (See Startup (Step 8) in Chapter 5.)
11. After configuration has finished, the CSI_B signal can be deasserted.
12. After the CSI_B signal is deasserted, RDWR_B can be deasserted.
13. The data bus can be x8 or x16.
Non-Continuous SelectMAP Data Loading
Non-continuous data loading is used in applications where the configuration controller
cannot provide an uninterrupted stream of configuration data—for example, if the
controller pauses configuration while it fetches additional data.
Configuration can be paused in two ways: by deasserting the CSI_B signal (Free-Running
CCLK method, Figure 2-9) or by halting CCLK (Controlled CCLK method, Figure 2-10).
The only time that the CSI_B signal must NOT be deasserted is during the loading of the
sync word or within two CCLK cycles after the loading of the sync word.
X-Ref Target - Figure 2-8
Figure 2-8: Continuous x8 or x16 SelectMAP Data Loading
PROGRAM_B
INIT_B
CCLK
CSI_B
RDWR_B
D[0:n]
UG380_c2_08_042909
Byte 0 Byte 1 Byte n
DONE
(1)
(2)
(3)
(4)
(5)
(6) (7) (8) (9)
(10)
(11)
(12)