On Saturday 10 June 2006 18:09, Peter Brett wrote: > On Saturday 10 June 2006 17:58, Hamish wrote: > > On Saturday 10 June 2006 16:40, Hamish wrote: > > > In addition, should we be doing anything with the WP and HOLD pins of > > > the SPI? They don't seem to be defined as an output for the module like > > > the other SPI input pins... Is hold simply to be tied and WP jumpered? > > > Or something else? > > > > Ah. Found this bit in the RevB schematics... They appear to be tied to > > Vcc? No write protect then? Is there any advantage to connecting WP_ to > > the XP6? (Are there any pins free on the XP6 to tie it to? If the XP6 can > > come up with WP_ low, then we can prevent spurious code from over-writing > > the SPI by accident (Or at least till something calls a write_enable > > function first). > > *boggle* Perhaps Timothy can help out here... I was under the impression > that it was a good idea to connect unused pins to rails through > pull-up/pull-down resistors rather than directly...?
Okay, I had a closer look at the schematics & the PROM datasheet, and I see what's going on. I would have tied the !CE pin high with a 4.7K pull-up to minimize any chance of junk signals being accepted by the PROM during board power-up, but it doesn't look like Howard's done that. I assume that's by deliberate choice. :) Peter -- Quake II build tools maintainer http://tinyurl.com/fkldd v2sw6YShw7$ln5pr6ck3ma8u6/8Lw3+2m0l7Ci6e4+8t4Eb8Aen5+6g6Pa2Xs5MSr5p4 hackerkey.com
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