PSA: There’s No SCK on CH32V003 SOP-16!
There. I had to say it. The short story is this: If you need SPI and want to use the SOP-16 package of the CH32V003 0.1$ RISC-V chip, well, think again. This is a short story of how I almost lost it.
They couldn’t have made a mistake, right?!
I got me a nice TSSOP20 package of the CH32V003, but because I am lazy and just wanted to try out this awesome linux-on-a-microcontroller project, I only made a respin of the original project and didn’t bother to ask for a stencil. Who needs one anyway?! Let’s solder everything manually!
It turns out it’s a pain in the ass to solder such small pins. And 20 of them! I also don’t need SO MANY pins. I managed well with 8 for my paws project so I bet the 16-pins variant is good enough for my next paws iteration (coming soon).
Quieting my impulse-purchase voice, I started doing the sensible thing and reading up the datasheet to figure things out before I buy it. I started reading up the datasheet but noticed something strange. The MOSI and MISO pins are there, but… where’s the clock signal pin?
Furthermore, scrolling down the datasheet, it seems the pin just… doesn’t exist on this variant…
And it is not remappable to ANY OTHER PORT-C PIN!
Community to the Rescue!
Baffled, I turned to the internet: Google didn’t help, ChatGPT blurted out nonesense. As a last resort, I turned to the hackaday community for help, maybe I am missing something?
Fortuately, the awesome community stepped to the rescue of my sanity. Apparently, yes. The chip is indeed missing the SCK pin for the hardware SPI to actually work.
As I have found absolutely no information about this on the internet, I felt the need to put the word out there. So, beware ye maker!
As for me, well, finding weird bugs in weird places is my MO so… Here’s to my first bug-on-a-chip. Cheers!
