ESP8266 Community Forum

- Tue Sep 16, 2014 6:30 am #627 As the GCC port seems to take shape and openocd/GDB claims to support the xtensa architecture I feel the urge in me to get some custom firmware running in the ESP8826

For that I started to design a breakout/dev board for the ESP8266EX (EX!) chip.

So far I included following features on the PCB :

ESP8266EX Chip
SMA Connector for the RF port (Antenna and for attaching a Spectrum Analyzer or RF Power Meter)
All ESP GPIOs and IO Pins brought out on Headers
FT2232H for UART , JTAG and flashrom (JTAG/flashrom selectable by jumpers)
Buttons for Reset and UART Boot (GPIO0)
Jumpers for the other boot modes (SDIO,Flash)

The PCB isn't completly layout'ed yet and the schematics are just whacked together at the moment (some parts are missing and values are wrong).

I'm posting this here because I'm looking for a review of the schematics and layout. Also when someone thinks it would be nice to have feature XY on the PCB as well please shout.

Probably I will send the files the dirtcheap pcb (thanks Squonk for the hint!) , so I will have some spare PCBs if anyone is interrested...

I know that the PCB Layout violates some of Espressif Layout recommendations , and is somehow contradictory to what I said in the Reference Layout thread

Here is a PDF of what i got so far , any comment is welcome

https://drive.google.com/file/d/0B_5UXa ... sp=sharing


And a nice shiny rendering how the PCB might look like
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- Tue Sep 16, 2014 6:53 am #630 Looks nice
Maybe that electrolytic capacitor (C8) between 3V3 and GND could be closer to ESP8266 chip?

Also, where is the Flash memory chip?

- Tue Sep 16, 2014 7:05 am #631 Thanks for the input elektronika_ba,

yep will move C8 . Flash is missing , I'm planing to add two flash chips (512kb,2mb) which are selectable by a jumper.

Also I'm a bit unsure on the SDIO Interface. I'm not sure if the ESP has a SDIO Host or if it is a SDIO Device .
SDIO Host wouldn't make not so much sense to me , or at least I can't think of a use other than attaching a SD Card to it.
Where a SDIO Device would make perfect sense , and what is also described in the Rockchip Espressif App Note , that way you could attach the ESP to a host processor.

I will probably just break the SDIO pins out on a seperate Header which has the same pinning as a SD Card...

- Tue Sep 16, 2014 7:57 am #635 Maybe SDIO can be used in both ways. Maybe you could load an entire website onto the SD card since ESP is already a web server

Does anyone know what differences are between the old and new *EX version of the chip? I am stuck with old ESP8266 version (early order).