Building a 16MB XeLL hacked image

[MastaG]

Well maybe it's because I have 380 ohm instead of 330.

[duggyuk]

Maybe, who knows. ... I'm still trying to establish if we should be using diodes rather than resistors based on sound info rather that the here-say that's currently doing the rounds.

[cory1492]

It is more likely a poor wire up/connection, cold joint, or severely out of tolerance resistor that messed with timing.

Diodes are technically superior as a protection circuit over the resistors, they also allow the line to switch hi/lo faster. Basically the two leads that have diodes on the J2D2 side of things are at 1.8V with their own internal pull ups, and on the GPIO side they are at 3.3V. GPIO should be set to low on 0's (which disperses the current/voltage from the weak pullup through the diode) and tristate/input/hi-z or whatever you want to call it (which allows pull up to 1.8V) on 1's, similar to I2C. High speed switching diodes do the job, the 0.7V drop across them is inconsequential and any signal from the 3.3V side would be blocked from reaching the 1.8V circuit (without thinking on breakdown usually at 50V or so.)

All the resistors would technically do (without going into resolving systems, it is more complex than just a straight circuit and thus should also be giving a voltage drop) is give a current drop in the hope any spikes would be dispersed to low enough of a current that it does no damage. The resistors should be fine, just not the same level of protection as the diodes.

Whether the SMC code in xenon hacked SMC is the same/will work with the falcon's diode method wiring is not known to me - I have no xenon to try it out on. I do know my falcon works fine in retail dash with TRST pulled high all the time (J2D2.4 ->J2D2.7) and the diodes in place. Any which way you look at it though, has absolutely nothing to do with building a XeLL hacked image...

[duggyuk]

thank you VERY much for the explanation... those of us who are not h/w savy (and I include myself in this group) really appreciate the info from people like you who take the time/effort to explain this in clear and simple to understand English