Hi
eh sometimes i just wanna shine, i guess
but well it was real nice seeing AVR code loaded and executed from SD
card
by bootstrap code in the 128 byte FlashROM of Actel
FPGA
the complete SD card bootstrap code takes 55 AVR instructions (from 64
available)
ah, the SPI is FULL software bit bang, there is no SD related hardware
peripherals.
well the AVR core in the
FPGA is little modified
1 ROM is mapped to RAM space both read write
2 SBI/CBI are modified to be able to write Carry to IO port
without [2] the code would be 56 instructions but still fit.
this code bootstraps from file copied to FAT file system, using NoFAT
(tm) method,
SDHC is not supported
I guess, without NoFAT, it might be possible to add SDHC support too,
but then initial
bootstrap would need to be in sector 0, what is possible but requires
special SD card
formatting tool
Antti
PS and yes, this just one bootstrap for the
FPGA-AVR module with Actel
PA3