Configuration data for serial daisy chains
requires special formatting because separate BIT files cannot just be concatenated together to
program the daisy chain. The special formatting is performed by write_cfgmem
(or Vivado device programmer) when generating a file from
multiple bitstreams. To generate the daisy chain file, specify multiple bitstreams following a
single -loadbit argument in write_cfgmem; for example:
-loadbit
"up|down <address1>
<bitfile1.bit>
<address2>
<bitfile2.bit>". Refer to the tool documentation for
details.
The write_cfgmem command
reformats the configuration bitstreams by nesting downstream configuration data into
configuration packets for upstream devices. Attempting to program the chain by sending
multiple bitstreams to the first device causes the first device to configure and then ignore
the subsequent data.