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The 3 cent Padauk PMS150C is.. Interesting to say the least. First of all there’s a lot this little MCU doesn’t do. It doesn’t have a lot of code space (1K Word), it doesn’t have a lot of RAM (64 bytes) and it doesn’t even do hardware multiplication. It doesn’t have an instruction for loading data from ROM either(Though there are ways of getting around this – but that’s a subject for another post). And of course – you can only program it ONCE.

So.. What can it do? Blink lights? Well yes.. and so much more.
Even though it has it’s limitations, there’s actually a lot you can do just by bitbanging with an 8Mhz microcontroller. As you can see in the screenshot from the IDE below, it’s actually meant to work with a bunch of peripherals – even though there is no hardware support for any of it.

Of course there’s a couple of very smart people over on the EEVBlog forum working hard at making an open toolchain for these chips, but I decided I couldn’t wait to get started and stuck with the manufacturer IDE, ICE and programmer.

To get the most out of the tools at hand, the IDE seems to expect you to use a mix of plain C, macros and assembly instructions, all mushed together in some pretty interestingly looking code. I’m probably not going to be popular for saying this but it actually feels very intuitive when you get used to it. It’s weird, but it’s “fun”.

After my initial mandatory “blinky tests” I decided to try something slightly more useful – controlling a WS2812B LED. Since the protocol itself relies on bitbanging with pretty tight timings, I figured this was a good test.”

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