Laurent Pinchart wrote: > > There are no internal pull-up or pull-down resistors on the MPC8248 GPIO > pins. I know our hardware engineer has a valid point theoretically. Does the > point stand practically, or does the MPC8248 > "state-of-the-art"(tm)(c)(whatever) technology make floating inputs safe ?
Well, Freescale's own layout recommendations recommend pullups or pulldowns for all input pins, but it's isn't clear what motivates that suggestion. The block diagram, Figure 37-21, is less than helpful. :) I recall a doc somewhere that showed the input protection circuitry ends up providing a modest pullup/down, so the line never truly "floats". But it's a very high-impedance path, and I can't seem to find the doc anyway so it could be for a completely different chip altogether. The part isn't going to blow up if you leave inputs unconnected, at least if you avoid high-EMI/RFI environments. But I can imagine the possibility of increased power consumption if I try hard enough. I would think that the magnitude would be completely swamped by the consumption of the rest of the chip, however... The technical answer might not be the best political one, at least not without Freescale-branded docs to back you up. I say, write the code and make everyone else happy. :) At least until someone plugs in that expansion module! b.g. -- Bill Gatliff [EMAIL PROTECTED] _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev