"I haven't found controllers that deliver 5V when flashing"
I agree with this halfway. All the CH341As I've personally seen supply 3.3VCC out of the box, but 5V logic. All of the schematics I've seen on the internet show this, so I don't think its just me. The 5V logic levels come from the CH341A which runs off the USB5V rail and is configured for 5VIO. 3.3VCC comes from a separate supply LDO. It is dumb, and I've wondered sometimes if the CH341A was designed to make things worse, though more likely an ad nauseam repetition of a bad design that is super cheap to produce and easy make a quick buck. All the discussions I've seen on the CH341A voltage issues have to do with IO voltage, not VCC. I wouldn't call the IO voltage issue "garbage". It is a legit concern, and only Winbond can say differently. On the X-230, the spec'd max VIH for the Windbond PROM is 3.7V with a 3.3VCC rail. The datasheet doesn't mention 5V IO tolerance. I don't doubt that 5V logic will work in many cases, but the real-world limit is set by physics, process, operating condition, and component skew. For a random PROM in a sufficiently large distribution of PROMs, we have to assume 5V will damage the IO, then your system won't boot, and you would have to change the PROM. It is a dice roll. (BTW, I'm not addressing the CPU IO. I don't have a schematic or CPU specs to know what kind of protection is on that end, but one may be risking that as well.) The RaPi method works well outt of the box @ 3.3VCC and 3.3V Logic using the latest Rasperian. One doesn't even need to connect to the internet. Suitable RaPi are available for $5-$10USD, but that won't give you the Pamona clip. The cheapest Pamona clip I've seen comes bundled with the CH341 for a few bucks, which is kind of funny. At least the RaPi can be used for other cool stuff. I've also read about some people using Arduinos to program BIOS PROMs, though that seemed like more work than a RaPi. > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Friday, March 13, 2020 8:00 AM, unman un...@thirdeyesecurity.org wrote: > > > 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 qubes-users+unsubscr...@googlegroups.com. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/qubes-users/20200313150039.GA15043%40thirdeyesecurity.org. -- You received this message because you are subscribed to the Google Groups "qubes-users" group. 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