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CM3 SDIO WiFi and eMMC

Thu Jan 18, 2018 6:49 pm

Is it possible to have an IO/carrier board with eMMC and WiFi?

I'd like to use softAP mode from Linux for WiFi, a 8 GB eMMC on my IO board, which would use the CM3 lite.

Otherwise, with the 4 GB eMMC on the CM3, how do people get WiFi on their IO board since the SDIO lines are occupied by the eMMC?

Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Location: Cambridge

Re: CM3 SDIO WiFi and eMMC

Thu Jan 18, 2018 9:13 pm

There are two SD controllers and (from memory), at least 3 pin mappings. SDIO devices such as WiFi must use the Arasan MMC controller, leaving the Broadcom SDHOST controller to run the SD card.

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Re: CM3 SDIO WiFi and eMMC

Fri Jan 19, 2018 4:25 pm

CM3 has 2 SDIO interfaces, namely SD0 and SD1.

If using CM3 with 4GB flash, SD0 is used to talk to the flash chip and boot from and can not be changed. This leaves the SD1 interface available for WiFi or additional emmc/sd card.

If using CM3L SD0 interface is available to the user and can be used for SD card or emmc for booting. This also leaves SD1 available for WiFi.

For more information refer to compute module data sheet, page 11, 18 and 19. ... T-V1_0.pdf

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Re: CM3 SDIO WiFi and eMMC

Mon Jan 22, 2018 4:33 pm

Sorry guys, I need to quickly order CM and CM board and I'm still a bit confused: with SDIO interface available, can I put wifi card with SDIO interface? Are there chipsets/modules ready for CM?

SD card on CM interface, is it avalable (for BOOT) only on CM3L? Or can I get microSD for booting also on CM3?

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