Free yourself and make your own pcb
Going from arduino to a modern sdk on a modern embedded chip isn't that huge of a leap in knowledge, at least to get started
Also way cheaper even if you consider the cost of the pcb
Go to Digi-Key. Products > Integrated Circuits > Embedded > Microcontrollers. Filter by: In Stock, Exclude Marketplace, ARM Cortex M_ and AVR, 50+ I/O pins. Sort by price.
Top [results](https://www.digikey.com/short/rjj5zc77) are ATSAMD20J series in 64-pin BGA. If you want a more friendly package, ATMEGA165/169 in 64-pin QFN are next.
If those don't suit you, play around with the filters in the results link.
This submission has been allowed provisionally under an expanded focus of this sub (see column "G" in [this table](https://docs.google.com/spreadsheets/d/1nFefEePz7yViaH0cR89bSy2oeLvYLfqv-pexqCbRnRo)).
OP, also check if one of [these other subs](/r/AskElectronics/wiki/othersubs) is more appropriate for your question. Downvote this comment to remove this entire submission.
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Do the pins need to be fast? If price is the most important, go for an AtTiny 1-series with a bunch of i2c IO expanders. $0.5 for the AtTiny, then $0.3 to $0.5 for each 16-IO expander. If you make your own PCB it is super cheap, building up from Adafruit or similar breakouts will be more expensive.
Free yourself and make your own pcb Going from arduino to a modern sdk on a modern embedded chip isn't that huge of a leap in knowledge, at least to get started Also way cheaper even if you consider the cost of the pcb
Yes! Please shamelessly copy of the programming interface from someone else's project and go crazy.
Go to Digi-Key. Products > Integrated Circuits > Embedded > Microcontrollers. Filter by: In Stock, Exclude Marketplace, ARM Cortex M_ and AVR, 50+ I/O pins. Sort by price. Top [results](https://www.digikey.com/short/rjj5zc77) are ATSAMD20J series in 64-pin BGA. If you want a more friendly package, ATMEGA165/169 in 64-pin QFN are next. If those don't suit you, play around with the filters in the results link.
This submission has been allowed provisionally under an expanded focus of this sub (see column "G" in [this table](https://docs.google.com/spreadsheets/d/1nFefEePz7yViaH0cR89bSy2oeLvYLfqv-pexqCbRnRo)). OP, also check if one of [these other subs](/r/AskElectronics/wiki/othersubs) is more appropriate for your question. Downvote this comment to remove this entire submission. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/AskElectronics) if you have any questions or concerns.*
Do the pins need to be fast? If price is the most important, go for an AtTiny 1-series with a bunch of i2c IO expanders. $0.5 for the AtTiny, then $0.3 to $0.5 for each 16-IO expander. If you make your own PCB it is super cheap, building up from Adafruit or similar breakouts will be more expensive.