Figure 1. Check Device ID (Step 5)
After the device is synchronized, a device ID check must pass before the configuration data frames can be loaded (see the previous figure). This prevents a configuration with a bitstream that is formatted for a different device.
If an ID error occurs during configuration, the device attempts to do a fallback reconfiguration.
The device ID check is built into the bitstream, making this step transparent to most designers. The device ID check is performed through commands in the bitstream to the configuration logic, not through the JTAG IDCODE register in this case.
The FPGA JTAG IDCODE register has this format:
vvvv:dddddddddddddddd:ccccccccccc1 where:
-
v= version -
d= 16-bit device code -
c= company code
See Table 2 for IDCODE values.