2021-05-08 from the editor of ~insom
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I have finally gotten two UARTs working from NetBSD on the
Allwinner/sunxi V3s board that I bought from AliExpress. I
purposely wanted to work with something more obscure and (at
the same time) more mainstream than a Raspberry Pi.
The Lichee Pi Zero (which is the board; honestly not much
more than a breakout board and some regulators for the V3s
chip) supports three UARTs and SPI and I2C. It also
technically supports Ethernet via some interface that I am
not (currently) interested in.
I haven't used NetBSD in a very long time so in way this
feels like retrocomputing -- which sounds like a diss
against NetBSD but should not. Linux is this _massive_ thing
now, and NetBSD has not been able to keep pace with all of
the features, although it's kept current on the features it
_did_ have and has added architectures. The source code is
readable and once again I feel like I can (kind of)
understand the system that I'm working on.
Getting a second UART working means that I can run PPP over
one of the serial channels (to /dev/ttyAMA0 on a Pi400
running Linux) and still have a serial console and access
the kernel debugger on the other serial port.
All of this is working towards a medium-term project for me:
add a driver to the NetBSD kernel. Specifically, a driver
for the ENC28J60 SPI-attached Ethernet controller.
(I expect many crashes, which is why access to the debugger
is neccessary)
I don't really need this, but working through the datasheets
of a small system and writing C (and learning about DTB) has
been a really pleasant experience. Not sure why; I don't
want to overanalyse.
Anyway this is closer to a blog post than a .project update
so bye!
