[En-Nut-Discussion] SPI Flash Interface to Ethernut

[Erik Lins]

> It's too early to release the schematics of the module. May be
> Erik Lins can provide some infos. But there's really nothing
> special with the SPI mem.

There is really nothing special with SPI flash memories. I connected 
the three SPI Signals and used some IO-pin for chipselect (I used PF0 
since I thought it's better to abandon an analog input, than some 
digital signal with more sophisticated timer, pwm, int, etc. funktion) 
and /RESET is connected in parallel to the AVR controller. I did not 
connect the RDY/BSY signal, since I didn't want to provide (wsste?) an 
additional IO-pin. The RDY/BSY status is also available in the internal 
status register and can be read via SPI at any time. Of course, 
connecting this signal to some interrupt would make write routines a 
bit more comfortable, but since page erase and programming time is up 
to 20msec, it's not a too big drawback to poll the status of this bit 
let's say every millisecond or every tenth millisecond. The write 
protect pin was connected directly to vcc in my application, but it can 
be left open, because it's pulled up internally.

The only filesystem/driver I know is uC/OS, which has a FAT filesystem 
for use with SD-Card or SPI flash devices, but it's not GPLed.

Cheers,
ER!K