Integration of PRK Firmware and R2P2

RubyKaigi 2026

Transcript

1. Integration of PRK Firmware and R2P2 RubyKaigi 2026 / hachi
2. Are you enjoying RubyKaigi?
3. What I want you to take away from this session
4. You can now write most keyboard firmware with R2P2! (Achieved by hasumi-san)
5. So what did YOU do? 🤔
6. • Hayao Kimura / hachi • Working at freee K.K. • Came from Osaka (Kyobashi.rb) • My first son was born in March!
7. • Hayao Kimura / hachi • Working at freee K.K. • Came from Osaka (Kyobashi.rb) • My first son was born in March!
8. • Hayao Kimura / hachi • Working at freee K.K. • Came from Osaka (Kyobashi.rb) • My first son was born in March!
11. By plane + car: 4h Car only: 9h Train: 10h Straight-line: 400km
12. Nemuro recommendations • For conveyor-belt sushi, I'm a Nemuro Hanamaru fan, not Kantaro. (source: Hanamaru official) • For seafood, try overnight-dried komai (source: Hokkaido Gyoren) ◦ Pairs endlessly with sake • Please try them before you head home
14. Today's agenda • Background & problems • What's needed to run R2P2 as a keyboard • Implementation and results • Wrap-up & next steps
15. Background & problems
16. What is PicoRuby?
17. PRK Firmware and R2P2 PRK Firmware R2P2 Concept Keyboard firmware Electronics platform First release 2021/11/10 2022/11/11 Can do Keymap config Split keyboards LED control Mouse VIA All sorts of electronics projects Can't do Gems unrelated to keyboards This is today's topic
18. A keyboard is an electronics project So... can't we integrate them?
19. What's needed to run R2P2 as a keyboard • USB HID support • ws2812 (LED) integration • Split-keyboard communication • Storage reduction
20. Problem 1: USB HID support • R2P2 didn't support USB HID at the time • Should be easy since it already uses TinyUSB • Personally, I want an option to disable HID
21. Problem 2: ws2812 integration Source: https://akizukidenshi.com/goodsaffix/WS2812B_20200225.pdfA
22. Problem 3: Split-keyboard communication
23. Problem 4: Storage reduction
24. Break Tips: Rokkatei's Strawberry Chocolate is highly recommended as a souvenir from Hokkaido.
25. Implementation and results
26. Problem 1: USB HID support
27. What is USB HID?
28. My implementation You can see the PR here
30. Just as I was about to open the PR...
31. hasumikin: By the way, what are you all talking about?
32. hachi: I'm going to talk about my ambition to integrate prk_firmware into R2P2
33. hasumikin: Oh really? I may not have mentioned that I merged this — FYI
34. Wait... the thing I wanted to do is already done...
35. hachi: When HID isn't used, I don't want the PC to recognize it as a keyboard — what do you think?
36. hasumikin> You mean toggling HID on/off at runtime? Sounds pretty hard, and even if we pulled it off I probably wouldn't want to merge it (feels unstable) lol
38. So I shelved the PR for now. Well, at least I got what I wanted for myself
39. Problem 2: ws2812 support
40. ws2812: the plan
41. Just as I was about to start implementing...
42. Any plans for the LED implementation in picoruby-keyboard? PIO is already on master and the idea is to use that. PicoRuby won't ship an easy "just light it up" feature — people who can code will do it themselves. ESP needs a different mechanism anyway.
43. Wait, picoruby-pio already exists... • hasumi-san had built a way to drive PIO from Ruby • On top of that, chobishiba-san implemented a ws2812 gem ◦ ksbmyk/picoruby-ws2812 • → No need for me to do it
44. Hold on — is hasumi-san already doing most of what I wanted to do?
45. Problem 3: Split-keyboard communication
46. Split-keyboard communication: proposal
47. I asked hasumi-san about it, and...
48. He built it for me
49. Break 2 Tips: At Raymon House Motomachi, a sausage shop by Carl Raymon in Hakodate, you can find a sausage called Thüringer that is exclusive to that location. It's absolutely delicious and highly recommended.
50. Problem 4: Storage reduction
54. RuntimeGem Architecture
57. But...
58. hasumi-san built something better, so I reverted mine
59. picoruby.org/terminal
60. picoruby.org/runtimegems • PRs welcome at picoruby/runtimegems
61. picoruby/runtimegems
63. So this...
65. hayaokimura/picoruby-rc-car
66. So, how did it all turn out?
67. My proposal vs. reality Problem My proposal Reality USB HID Toggle via boot.rb Always enabled ws2812 Build picoruby-ws2812 Roll your own with picoruby-pio Split-keyboard communication Propose a half-duplex picogem bitbang uart Storage reduction Place runtime_gems via rake Web-based one-click install
68. None of the code I wrote survived in PicoRuby
69. Ugh, how frustrating...
70. Why did this happen? • I should've opened an issue at the same time as my proposal • Too much overlap with what hasumi-san was doing
71. But that's okay
72. Conclusion • You can now write keyboard firmware with R2P2 • Lots of exciting implementations have been added — USB HID, PIO, BLE::UART, and more — so please give them a try • Time spent chasing your own curiosity is never wasted • What I learned (USB HID, runtime switching, PIO) stays with me • I'll keep contributing to PicoRuby however I can, starting tomorrow
73. What's next • Keyboard debugging & samples • Expanding RuntimeGems • BLE keyboards, split keyboards • More activities that make hasumi-san jealous While I'm off improving the ecosystem and trying to fix tiny bugs in the language (doesn't mean I actually fixed them), everyone else is happily building fun PicoRuby apps — isn't that a bit unfair?
74. One last plug
75. Thank you for listening 🙏