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Altera_Forum
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13 years ago

NIOS II and Cyclone III Remote Update

Have spent several days now searching and reading and think I am nearly there... but not quite. I am using the NIOS II core with SOPC builder. I use Quartus II for the FPGA image. This is a projec...
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Altera_Forum
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12 years ago

The remote update register addressing is a bit tricky; it maps to 2 ports of remote update megafunction: param and read_source.

param is mapped to address bits 0-2 , while read_source is mapped to bits 3-4.

Then address 0x04 refers to param 100 (boot address) and read_source 00 (current status)

Address 0x0C refers again to param 100 (boot address) but read_source 01 (past status, before reconfiguration)

Moreover, the boot address format is different between writes and reads: 22bits for writes and 24bits for reads.

The values you read are correct up to the last 4 bits, which instead seem somehow random. Are you sure everything is properly connected?

If your Nios runs at a frequency different from 25MHz you should have a clock crossing bridge between data master and remote update MM slave.

If everything looks ok, try reading the register twice and check if you get the same value. If not, you definitely have a problem with connection or timing.