Sorry to resend this. I sent it before I was done accidentally ========================================================
Charles Steinkuehler wrote: > > Mike Noyes got the sst guys to send a schematic and some details about their > ATA-Disk module (ADM) and it's write-protect features: > > > >Here is the 40pin 5V ADM schematic. This is using the LD017 > > >controller. In the schematic R8 is used as an option for WP. I think this is the crux. It's being used. It's being tied to ground by the presense of ground on IDE cable pin 30, and the existence of a zero-ohm resistor, ie. a short to gnd. > > >The ADM using the LD016 was never released to production. It was build > > >for customer evaluation purpuses, only, and it does not support the WP > feature. > > > > > ><<LD017 SADM.doc>> > > Looking at the schematic, taking into account the information above, it > looks like the ADM *DOES* support a write-protect function, but it's not in > the form of an easily accessible jumper. What I have determined: > > * If you have an ADM module using the LD017 controller chip, you can enable > a write-protect function (per above comments). Note that the write-protect > feature is particular to THIS SPECIFIC DEVICE, and is not a general feature > of IDE devices. Not a general feature if IDE I would agree. For a regular IDE drive, disconnecting or strapping an IDE pin low or high, such as DIOW or DIOR (23 or 25 I think) would interrupt the writing of command signals to the drive's onboard controller. At least that's how I understand it so far. > * There is a zero-ohm resistor (used as a build-time configuration option) > to connect the write protect line of the controller IC to pin 30 of the IDE > interface (from the above comments, and the schematic). > - If R8 is populated, pin 30 controls the write-protect Isn't pin30 gnd on the IDE cable? If so, then the R8 being populated with a short means this gnd is present on the DOM controller, and the fact that the module is write capable in this configuration infers that gnd=write capable. > - If R8 is vacent, the device behaves normally (ie no write-protect) I see the exact opposite. It's gnd now according to the docs with R8 present and it's write enabled. If you remove R8, then you'll float that line. But is floating it proper, and does that write-protect the device? On the other hand, the tech told Mike the following: > I just got off the phone with one of the tech support > guys at SST. He sent me the schematic for the ADM device. They placed a > resister R-8 on the ADM that can be shunted to ground to enable WP. He said > this will work with standard IDE/motherboard configurations. So the tech says that the resistor can be shunted to ground. I thought that's what the schematic says it's doing because pin30 on the IDE cable is ground. > Interpolating a bit, since I don't have a unit to test, and the PDF doc > indicates a WP# jumper that doesn't exist: Agreed. It's not in the schematic. > The device should be write-protected if you tie the write-protect line from > the controller chip to ground. Since R8 is between the controller's > write-protect signal and IDE pin 30 (which should be ground on a standard > IDE cable), it should be possible to place a switch across the pads of the > (presumably missing) resistor R8. If the switch is "on", or shorted, the > device should be write-protected. If the switch is "off", or open, writes > should be possible. I agree with all this, but I have a problem because the schematic says that it's already tied to pin30 that's listed as ground. If in fact the R8 is missing, then as you mentioned, shunting this to ground means write-protect. But I'll claim, on the other hand, that if it has an R8 in place already, then it should be tied to Vcc to do the opposite. Why would floating it be appropriate. I dunno, I've been out of building circuits for a bit. Best, Matthew _______________________________________________ Leaf-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/leaf-devel
