gregeric
Posts: 1508
Joined: Mon Nov 28, 2011 10:08 am

SHABPi - SDIO WiFi for Pi Zero

Sat Feb 27, 2016 12:07 pm

Here's my slim WiFi board made to fit the Pi like a glove. Slipper, pants, shoe have all been suggested, but I'm a literal sort so it's SHABPi - SDIO Hardware Attached Below Pi.
SHABPi-Side.jpg
SHABPi-Side.jpg (60.38 KiB) Viewed 9088 times
SHABPi-Bottom.jpg
SHABPi-Bottom.jpg (62.72 KiB) Viewed 9088 times
SHABPi-Top.jpg
SHABPi-Top.jpg (44.67 KiB) Viewed 9088 times
Wholly derived from ajlitt's brilliant write-up of his equally excellent hack of an ESP8266 IoT module at https://hackaday.io/project/8678-rpi-wifi.

Features:
  • Slim 65x30x0.8mm PCB mounts directly against the reverse of the Zero.
    ESP-12E/F WiFi module in 1 or 4-bit SDIO mode gives ~40Mbps up/down.
    Pi reboot detection to reset the ESP & ensure correct reloading of driver.
    Full size SD socket option for memory cards / peripherals.
    USB port duplicated on end shifts metalwork away from WiFi SD Cards.
    Killer feature - power LED :D.
Gobbles up GPIOs 22-27 in 4-bit mode, or 22-25 in 1-bit mode, so watch for compatibility with HATs.

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adun
Posts: 102
Joined: Fri Mar 20, 2015 9:25 am
Location: Switzerland

Re: SHABPi - SDIO WiFi for Pi Zero

Sat Feb 27, 2016 1:01 pm

Really great work :)
Have you also tested to use your sd card socket along with the uSD card of the Pi Zero?
As far as I know the SD interface is used (on GPIO 48-53) and can't be redirected to GPIO 22-27.

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 1897
Joined: Thu Jul 11, 2013 2:37 pm

Re: SHABPi - SDIO WiFi for Pi Zero

Sat Feb 27, 2016 1:06 pm

adun wrote:Really great work :)
Have you also tested to use your sd card socket along with the uSD card of the Pi Zero?
As far as I know the SD interface is used (on GPIO 48-53) and can't be redirected to GPIO 22-27.
There are two SD interfaces on the SoC. One's capable of SDIO (Arasan eMMC controller), the other is a bit more basic (Broadcom SDHOST interface).
Rockets are loud.
https://astro-pi.org

gregeric
Posts: 1508
Joined: Mon Nov 28, 2011 10:08 am

Re: SHABPi - SDIO WiFi for Pi Zero

Sat Feb 27, 2016 1:09 pm

Turns out there are two SDIO interfaces on the Pi. One IP bought in from Arasan (emmc), the other designed by Broadcom (sdhost).

In this setup, sdhost does uSD boot duties, while the Arasan block on GPIOs 22-27 does SDIO.

Yep, SD Card in the board's socket comes up as /dev/mmcblk1 device. But you can't have both WiFi & SD card at the same time, one or the other.

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adun
Posts: 102
Joined: Fri Mar 20, 2015 9:25 am
Location: Switzerland

Re: SHABPi - SDIO WiFi for Pi Zero

Sat Feb 27, 2016 1:27 pm

A good to know ;)
Btw is the compute module using the Arasan sdio interface for its emmc ?

gregeric
Posts: 1508
Joined: Mon Nov 28, 2011 10:08 am

Re: SHABPi - SDIO WiFi for Pi Zero

Sat Feb 27, 2016 1:44 pm

adun wrote:A good to know ;)
Btw is the compute module using the Arasan sdio interface for its emmc ?
CM can use either. The default is sdhost, switched to emmc with dtoverlay=mmc in config.txt (try this if your CM does not come up).

gregeric
Posts: 1508
Joined: Mon Nov 28, 2011 10:08 am

Re: SHABPi - SDIO WiFi for Pi Zero

Sun Feb 28, 2016 12:29 pm

Just built one on to another Zero with the 40-pin header this time so useful things can be done.

Showing live weather summaries from bbc.co.uk:
SHABPi-ScrollpHAT.jpg
SHABPi-ScrollpHAT.jpg (63.41 KiB) Viewed 8862 times
Another plus from relocating the data uUSB to the side is that the Zero + pHAT sit flat on the table whichever side you put it down.

gregeric
Posts: 1508
Joined: Mon Nov 28, 2011 10:08 am

Re: SHABPi - SDIO WiFi for Pi Zero

Sun Mar 13, 2016 6:54 pm

I now have the SD socket switching as it was designed to be: WiFi dropping out while card is inserted. Head over to hackaday to see the details.

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