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MPC8306 reset configuration words in SPI boot

Question asked by John Clair on Dec 10, 2014
Latest reply on Dec 15, 2014 by Serguei Podiatchev



We're booting from an SPI flash device as per SPI Boot in section 5.3 of MPC8306RM rev2. For this, we've strapped the reset configuration inputs all high to set CFG_RESET_SOURCE[0:3] to 4'b1111. RCWH and RCWL are the first two configuration words stored in the SPI flash at offset 0x80. The board loads the RAM configuration words from SPI flash, loads the bootloader and boots without issue, but the RCWL is not set as per the value in SPI flash. We're trying to set 0x44040008 and we instead read back 0x44040044 at boot.


Table 4-5 has changed between rev.1 and rev.2 of MPC8306RM and what read "Reset configuration word is loaded from On Chip ROM boot via SPI" now reads, "Hard-coded reset configuration word for SPI boot".


Does this imply that we cannot write RCWH and RCWL when booting from SPI? If so, where can we find the details for the "Hard-coded" reset configuration word (noting that section does not provide details for a CFG_RESET_SOURCE of 4'b1111)?