> I like the Raspberry Pi RP2040 a lot. It's relatively cheap (around $1 USD) and has tons of on-board RAM - 264 KB in fact! It also has what is called Programmable IO, or PIO.
I wonder how benchmarks would compare between the RP2040 and, say, a Z80.
It would destroy the Z80. It's a 32bit, dual core CPU running at 133MHz. Even single cored it'll thrash a Z80. Heck, I bet you could create a drop-in replacement board for the Z80 using an RP2040.
My sweet spot of choice between power and price is the ESP32 S3 (2x core @ 240mhz) at ~$6 per board, but yeah, the power to dollar ratio is crazy these days, across the board. And they are absolutely tiny and sip power if you write the code well.
The key here is the "PIO" which you won't find on a Teensy. It lets you do extreme "bit banging" tricks including generating video. People have even implemented Ethernet on it. I've used it for some custom serial protocols ("Weigand") used by alarm panels.
The RP2040 is a Cortex-M0, which is about the smallest core you find on modern systems but still a pipelined 32 bit RISC machine running in the dozens of MHz.
Note though, that the article is really about the PIO device on these SOCs', which isn't part of the main CPU at all. It's sort of a very limited programmable hardware engine for the specific task of doing PCB level interconnect using GPIO and lightly buffered streaming. In some sense it's like a thematic midpoint between an FPGA and a CPU.
It's... honestly it's just really weird. And IMHO has really, really, REALLY limited application. It's for people who would otherwise be tempted to bitbang an I2C or UART, but not for ones who can put hardware on the board themselves, or who have a FPGA handy, or even for people who want to do non-trivial stuff like QSPI displays[1] or whatnot.
Basically PIO smells like a wart to me. I genuinely don't know who wants it. Regular hackers aren't sophisticated enough to use it productively and the snobby nerds have better options.
[1] The linked article appears to be doing a quarter-VGA display in 3-bit/8-color, and is sort of right at the limit of the power of the engine.
CRT tech is neat, the flat ones are cooler
https://www.youtube.com/watch?v=pjzK-Lppa1c
> I like the Raspberry Pi RP2040 a lot. It's relatively cheap (around $1 USD) and has tons of on-board RAM - 264 KB in fact! It also has what is called Programmable IO, or PIO.
I wonder how benchmarks would compare between the RP2040 and, say, a Z80.
It would destroy the Z80. It's a 32bit, dual core CPU running at 133MHz. Even single cored it'll thrash a Z80. Heck, I bet you could create a drop-in replacement board for the Z80 using an RP2040.
Note it was possible to use a Z80 to function as a display controller, people used to do it back in the day...
https://archive.org/details/Cheap_Video_Cookbook_Don_Lancast...
Crazy what you can buy nowadays like the Teensy 4.0 with 600MHz base clock
Granted that's $20 not $1
My sweet spot of choice between power and price is the ESP32 S3 (2x core @ 240mhz) at ~$6 per board, but yeah, the power to dollar ratio is crazy these days, across the board. And they are absolutely tiny and sip power if you write the code well.
The key here is the "PIO" which you won't find on a Teensy. It lets you do extreme "bit banging" tricks including generating video. People have even implemented Ethernet on it. I've used it for some custom serial protocols ("Weigand") used by alarm panels.
Really I guess I don't know what that is then as I buy the Teensy since it has so much IO, multiple UART, multiple I2C busses, sd card reading, etc...
edit: interesting
(Teensy | Pico)
Special Features: CAN Bus (3x), SDIO, S/PDIF | PIO (Programmable I/O) (8 SMs)
The RP2040 is a Cortex-M0, which is about the smallest core you find on modern systems but still a pipelined 32 bit RISC machine running in the dozens of MHz.
Note though, that the article is really about the PIO device on these SOCs', which isn't part of the main CPU at all. It's sort of a very limited programmable hardware engine for the specific task of doing PCB level interconnect using GPIO and lightly buffered streaming. In some sense it's like a thematic midpoint between an FPGA and a CPU.
It's... honestly it's just really weird. And IMHO has really, really, REALLY limited application. It's for people who would otherwise be tempted to bitbang an I2C or UART, but not for ones who can put hardware on the board themselves, or who have a FPGA handy, or even for people who want to do non-trivial stuff like QSPI displays[1] or whatnot.
Basically PIO smells like a wart to me. I genuinely don't know who wants it. Regular hackers aren't sophisticated enough to use it productively and the snobby nerds have better options.
[1] The linked article appears to be doing a quarter-VGA display in 3-bit/8-color, and is sort of right at the limit of the power of the engine.
Cool project! I've been doing software for so long but originally got an EE degree. I miss messing around with hardware.