ESP8266 pHAT schematic


Hi, please can you publish (or send to me :-) the circuit diagram (schematic) for the ESP8266 pHAT? I’ve just bought one and have it working fine, but I now want to take things further by using more pins on the module. However I have no idea which pins are currently connected or in use and which lines go where on the board.

thanks a lot



The GPIO pins used on the Pi header itself are documented here:

… if you mean the pins used on the ESP8266 itself, they are either broken off or used for communication with the Pi (as above pinout), except for a couple that are not recommended for day-to-day use in projects.


Hi, thanks for the below information, but it’s not what I was looking for (at least, it does add some information, but not nearly sufficient). There are several components on the board as well as the ESP8266 module itself, which are not explained. The information in the link below mentions an ADC channel, but no info is given on whether there is interface or buffering components for this interface on the board (rather than just the bare input on the module).

Many pHATs are self-contained for performing a fixed function (for example the DAC pHAT) so there is no need to provide schematics. However the ESP8266 pHAT is designed for prototyping and experimentation (the board even contains a prototyping area for this purpose) so it is very important that a circuit diagram be provided, showing ALL connections and components on the board. This is the only way that experimentation can be carried out without the risk of damage or unintended consequences.

Please would you provide the full circuit diagram for the board?

Thanks again



I am still unsure what you are after… the ESP IOT pHAT is essentially an ESP8266 breakout, and what you interact with, namely 6 I/O (5 of which provide PWM capability) and the ADC come directly from the ESP8266-12 chip, without added circuitry in the path. The rest is level shiting and protection circuitry so it can be programmed with the Pi.


HI again, what I need (and telling from the comments from other customers across the web, they need it too) is the circuit diagram of the pHAT board (the Americans call it a schematic). You’ve hinted at the need for this in your reply “The rest is level shifting and protection circuitry…” (typo corrected ;-) - in order to experiment with the board it’s essential that all lines, components, pullups, etc. are understood. For example, what power supply decoupling is on the board; which power pins are used; what are the 6 resistors for that are lined up alongside the module; how does the drive to the firmware LED work and where does it connect to (there’s what looks like a transistor on the board, driving the LED, but that’s guesswork).

So in summary, if you’re supplying a board that’s intended as an experimentation base, it’s essential that the circuit diagram is provided with it (also, a link from the Pimoroni website product page to the link you sent in your first reply would be very helpful).

So please would you supply the circuit diagram (schematic) for the pHAT board.




I’ll pass on your request…


Thanks a lot; I appreciate it.Doug


Hi @doughadfield,

Sorry, I’m afraid we currently don’t have a published schematic for the ESP8266 pHAT, mostly due to a complete and total lack of time. This may change in future, but I couldn’t give any estimate as to when.


thanks for letting me know. I suppose I’ll have to work the lines through with a multimeter to make sure I understand what’s going on. I do urge you, however, to supply a schematic as part of the product as soon as possible, as it is currently a major omission for what is intended as an “experimenter” board.

thanks again for your responses