isolating the boot pins

Hi all,

I need a gpmc bus and a serial port with hardware flow control - and that means I need to use P8 pins 31-46, which vexingly double as boot-mode-setting pins.

These pins have to be isolated from other signals during boot, or the BB won't boot correctly.

Since I'm using 74xx245-style 3/5V level translators anyway, I can just use the tri-state function of the translators/transceivers to isolate these pins (high in = high Z), I think.

What signal can I use to drive the tri-state functions? I was thinking the gpio1_28 signal could be used, since the "ball reset state" and "ball reset release state" values are both high for it.

Is that the path to happiness, or is there a better One True Way to make these pins useful?

- Mike

We use the SYS_RSTn line to do this on a new memory expansion cape that we are working on. It works fine.


Thanks, that's very useful to know!

- Mike