ESP-12F Raspberry Pi GPIO SDIO Wifi

I've got the headphone jack and audio in place. I'll update the instructions to make it simpler to setup.

Theres an intermittent high pitched whine and some faint clicking/crackling when nothing is playing, if you play something from one channel the other has lots of white noise.

WiFi (and possibly SD) access causes extra electonical noise.

Its good enough for playing sounds through a crappy speaker in a project, or for simple radio streaming (you don't hear the noise over the audio) but not for any kind of serious listening or for headphones.

I have filters the same as on the Pi 1, and I think my routing is OK. So the only thing I can think of is that the routing of GPIO12/GPIO13 on the Pi zero itself causes it to pick up noise. Or perhaps I need better filtering on GND?

I've tried it on a board with the 5v regulator populated too.

(I did populate all the audio filter passives)

On the positive side I routed the right and left channels the right way around, which I'm happy about as I was worried I'd mixed them up!

I have a few spare pcb kits up on eBay. I'll include the other smt parts but you'll need your own ESP module.

Not sure if it'll be good value for those not in the UK, As I'm not sure what eBays international parcel forwarding service costs. But it's the only way I'll sell abroad.

http://pages.ebay.com/link/?nav=item.view&id=262291855253&alt=web

As suggested by @haddyhad I've put the flash into sleep mode with the sleepflash.py utility I've added here https://github.com/jacksonliam/rpi-bitbang-spiflash. The flash seems to stay asleep through power cycles (at least short ones). And I enabled 4 bit SDIO mode.

Its possible that the driver could send the flash wake up command which would break comms with the module, but I'm not sure how likely it is that would happen.

453MB 5.8MB/s 00:42 ETA

Thats 46.4Mbit/s - The ESP8266 supposidly supports MCS7 / HT20 so in theroy you should be able to get near 72.2Mbit/s but according to iwconfig mines only connecting to my router at 54Mb.

Has anyone seen it sync higher than 54Mb?

Overclock to 62.5Mhz

I tried the overclock 'sdio_overclock=62' as suggested by @ajlitt but unfortunately the card doesn't start.

[    3.587837] mmc1: Got command interrupt 0x00030000 even though no command ope                                                                                                             ration was in progress.
[    3.587893] mmc1: Got command interrupt 0x00030000 even though no command ope                                                                                                             ration was in progress.
[    3.598324] mmc1: Controller never released inhibit bit(s).
[    3.648352] mmc-bcm2835 3f300000.mmc: no support for card's volts
[    3.648371] mmc1: Got command interrupt 0x00030000 even though no command ope                                                                                                             ration was in progress.
[    3.648414] mmc1: error -22 whilst initialising SDIO card
[    3.658962] mmc1: Controller never released inhibit bit(s).

[   46.476820] mmc-bcm2835 3f300000.mmc: no support for card's volts
[   46.476830] mmc1: error -22 whilst initialising MMC card
[   46.526554] mmc1: Controller never released inhibit bit(s).

Here's the money shot!

Ignore the poor 0603 soldering, I've only done QFP smd before!

Didn't bother with the resistors just did solder bridges. Getting 28Mbit/s pulling a file from my server.

I got the header placement wrong, so the Pi and board are offset by about 1mm, I'll fix it in easyeda but am not bothered enough to order more boards!

Next I'll try putting the flash to sleep with 4 bit SDIO.

I want to try the audio but the pack of smd resistors I bought doesn't have any value below 600 ohm for some reason!