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--- Quote End --- Maybe was this : found in Altera "Nios II Embedded Design Suite 6.0 Errata Sheet" : development boards
this section lists any issues related to altera development boards.
intermittent failures while accessing compactflash card
the nios ii development kit version 5.0 and higher includes a compactflash controller peripheral suitable for
interfacing to compactflash cards in true ide mode on nios development boards. in order for true ide mode to
operate, compactflash cards require that the atasel_n input be driven to ground during power-up.
the compactflash controller peripheral includes a configurable power register used to power-cycle compactflash
cards in nios ii software through a mosfet on the nios development boards. however, in certain development
boards, power to the compactflash card will not turn off completely during this power cycle operation. because
of this, the compactflash might not sample the atasel_n pin during the power-cycle operation after fpga
toolchain (gcc, gdb, etc.)
altera corporation 11
may 2006 nios ii embedded design suite 6.0 errata sheet
configuration when this pin is driven to ground. instead, the compactflash card might sample the atasel_n pin
when power is first applied to the development board, when i/o are not yet driven by the fpga (before fpga
configuration).
workaround: if you encounter errors with compactflash when using the nios development boards, try one of
the following:
■ use a different compactflash card. certain cards are more susceptible to the power-cycling issue than others.
■ modify the nios development board. this is recommended for users who are familiar and comfortable with
board-level modifications. disconnect pin 9 (atasel_n) on the compactflash socket on your nios
development board and tie this pin to ground. note that the compactflash socket uses a staggered numbering
on the pins (starting from pin 1: 1, 26, 2, 27, ...); refer to the compactflash association specification for
right-angle surface-mount connectors for exact specifications on this connector. this modification will
permanently enable true-ide mode operation.
