A low-cost 8-bit AVR64DD32 microcontroller can host a very limited web service for one URL. The chip includes one 8-bit AVR core, up to a 24 MHz clock, 8 KB static RAM, 64 KB flash, and 256 bytes EEPROM. The project relies on the fact that the chip’s I/O pins top out at 12 MHz, making Ethernet impractical because 10BASE-T transmits at 10 megabits per second and uses Manchester encoding that doubles the effective wire rate. A dedicated Ethernet chip could solve the issue but would delay completion. Instead, Serial Line Internet Protocol (SLIP) is used to carry IP traffic over serial lines, enabling web access despite the hardware limits.
"The I/O pins on the AVR max out at 12 MHz, which Maurycyz explained meant that it wouldn't be possible to use Ethernet for the project, as the data flow from even the aged baseline Ethernet connection of 10BASE-T is too fast for the chip to handle."
""10BASE-T still runs at 10 megabits/second," Maurycyz wrote. "Worse, it uses Manchester encoding: a zero is sent as '10' and a one as '01,' so 10 megabits of data is actually 20 megabits at the wire.""
""The proper solution is to buy a dedicated Ethernet chip from DigiKey, but then I'd be waiting weeks to finish this project," Maurycyz noted. Instead of waiting, he decided to take a different approach by turning to Serial Line Internet Protocol ( SLIP), just like the guy who turned a discarded vape into a web server last year."
"For those unfamiliar with SLIP, it's a 38-year-old protocol designed to encapsulate IP traffic for transmission over serial lines, and it was widely used to make internet con"
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