As described in other threads, I'm working on embedding a USB-to-serial adapter in one of my MSP430 projects, and I've found the perfect adapter for this purpose. It's smaller than the other adapters, has the right pinout, and even comes with a micro-USB socket onboard.
The chip used in the adapter is the CP2102 from Silicon Labs. But there's a problem. The output labeled in silkscreen as "3.3V" actually measures4.25V. And it's not just the one I received:
It seems that all modules of this design are like that. And the CP2102 is definitely a 3.3V part. So it's either something wrong with the board layout, or something the manufacturer has done intentionally to get that output up close to 5V.
This is a deal killer if it can't be corrected because all the MSP430 parts would likely be destroyed by voltage that high. Oh, and it's not just the3.3V output, it's DTR and TXD too.
I've been on the Silabs forum, and so far nobody has come up with an explanation for how this could be done. If everything is connected as it should be, which appears to be the case, this shouldn't be possible.
So what I'd like to do is contact the manufacturer and try to get some information about how this was done in the hope that it will be something I can reverse easily. The markings on the board are:
I've seen CJMCU elsewhere in relation to drones and other stuff, but Google gives me no home page or any other info about them.
Does anyone here know anything about CJMCU? Where would you go to find them?