On Fri, Mar 13, 2020 at 03:35:05AM +0000, Mike Karasoff wrote: > As far as the voltages go, I'm not sure I understand unman's "garbage" > comment. The PROMs on your X-230 are 3.3V logic, but the CH341A programmer > usually has 5V logic. I've heard that some CH341A are 3.3V, but that seems > more because there are several different places in China producing the same > board and so its kind of random. > > I think you can use 5V logic to program these ICs, but you are doing so at > your own risk. There is no current limiting resistor on the CH341A board, > and some of the CH341A ICs have no label, which indicates a potential "back > ally" fab (i.e. counterfeit) that is common with low end Chinese electronics. > Point is, you'd be driving you motherboard with a potentially out of spec, > using an unknown IC at the wrong voltage, without current protection. This > is not necessarily safe for your Mobo, but it *might* work for you. > > There is a mod to turn your programmer into a 3.3V device, but it seems the > mod doesn't work on newer programmers that don't have labels on the chip. It > didn't work for me, and internets reports that it didn't work for others. I > used a Raspberry Pi instead : > https://tomvanveen.eu/flashing-bios-chip-raspberry-pi/ The trick for the > RaPi was the arg "spispeed=512". I connected the Pamona clip included in the > CH341A Kit to the RaPi using fly wires, so my CH341A wasn't completely > useless, and was actually cheaper than the clip alone. China. >
If you look, my comment related to voltages AND chip id. On the voltage front, my experience differs from what you have heard. I haven't found controllers that deliver 5V when flashing, and I've tested some. There's some debate about whether the specs include an internal LDO or not, depending on your knowledge of Chinese and reading of the spec. All I can say is that I've used numerous cheap (and expensive) programmers without mishap. (And, to repeat myself, nemeth reports the same, as did Cornelius who provided the first schematic.) So let's be clear - you are buying a cheap chip of unknown provenance. That's the real risk here. Some (which? some black ones? Which black ones?) controllers may have a voltage issue, which may not even be an issue. The second question is the need to identify the chip - with an x230 (and most other lenovos I have worked on), you can read and write using any of the proferred chip ids, with identical results - Any one should be able to confirm this for themselves. Pick up a motherboard from ebay, and start practise. gets you experience at minimal risk and cost. -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/20200313150039.GA15043%40thirdeyesecurity.org.
