I've hemmed and hawwed about how to do WiFi, but rev 0 will be a dev board of some kind so I'll be exposing an SDIO, a SPI and a USB interface to mess around. esp-hosted-ng looks really interesting but I need to see if it works. Would also let me try some other SDIO interfaces if needed. Some links: - [cfg80211](https://wireless.docs.kernel.org/en/latest/en/developers/documentation/cfg80211.html) part of the linux kernel for wireless - [esp_hosted_ng/README](https://github.com/espressif/esp-hosted/blob/master/esp_hosted_ng/README.md) SPI connections | Function | ESP32 | ESP32-S2/S3 | ESP32-C2/C3/C5/C6 | | :---------: | :---: | :---------: | :---------------: | | CS0 | IO15 | IO10 | IO10 | | SCLK | IO14 | IO12 | IO6 | | MISO | IO12 | IO13 | IO2 | | MOSI | IO13 | IO11 | IO7 | | Ground | GND | GND | GND | | Handshake | IO2 | IO2 | IO3 | | Data Ready | IO4 | IO4 | IO4 | | ESP32 Reset | EN | RST | RST | SDIO connections | ESP32 Pin | ESP32-C6 Pin | ESP32-C5 | Function | | :-------------------------------------------------------------------------------------------------------------------------------: | :---------------------------------------------------------------------------------------------------------------------------------: | :---------------------------------------------------------------------------------------------------------------------------------: | :------: | | IO13+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html) | IO23+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | IO13+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html) | DAT3 | | IO14 | IO19 | IO9 | CLK | | IO15+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html) | IO18+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | IO10+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html) | CMD | | IO2+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html) | IO20+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | IO8+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | DAT0 | | IO4+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html) | IO21+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | IO7+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | DAT1 | | EN | ESP Reset | ESP Reset | Reset | | IO12+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html) | IO22+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | IO14+[pull-up](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c6/api-reference/peripherals/sd_pullup_requirements.html) | DAT2 | | GND | GND | GND | GND | I found some other WiFi chips to consider: [ATWILC3000](https://www.digikey.ca/en/products/detail/microchip-technology/ATWILC3000-MR110UA/5322331) , $18 from digikey [LBEE5PK2BC](https://www.digikey.ca/en/products/detail/murata-electronics/LBEE5PK2BC-771/16374386) $26 dollars, wifi 5, not a module [Ezurio 453-00085R](https://www.digikey.ca/en/products/detail/ezurio/453-00085R/15850985) $15, module [RTL8723BS](https://www.realtek.com/Product/Index?id=610&cate_id=194) really cheap, hard to get ## ESP32 notes https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/sd_pullup_requirements.html this looks concerning about pull ups. Might have to selectively populate some pins during bring up. https://github.com/espressif/esp-hosted/blob/master/esp_hosted_ng/docs/setup.md