Hmm... Do I put this in General Electronics or Project Guidance? Hmm...
Thanks for taking the time to read this post. I am trying to do a project which requires some pretty hefty work as a web server. The first version used the WiFiEsp library and an ESP-01. It "works" but lacks in power. AT commands over serial just doesn't provide enough power.
So, the new version will attempt to use an ESP-12F over SPI using the WiFiSpi library. My "Arduino" uses an ATMEGA1284 at 20MHz and runs on 5V. The board is already completed and I don't want to redesign everything for 3.3V,
I have cobbled a schematic together from various sources. The logic level converter is from a SD card module. The WiFiSPI library suggests a safe CS circuit because the ESP won't boot if the CS pin is low. That left one channel open which Jiri suggested I should use for RST. I am trying to implement a power switch (EN pin) using a PNP transistor. I brought out the TX0 pin just because the library can send debugging info via serial. Building a prototype is no small task because the ESP has a 2mm pitch.
If you have read this far, please take a look at the schematic and let me know of any errors you may detect. I sincerely thank you.
@ Railroader: Did I say it failed? Actually, the entire first WiFi project works but lacks WiFi power due to being serial based. I didn't ask a single question about coding and the wiring is in the schematic.
My first WiFi project uses 10 libraries, a 128 x 64 LCD, WiFi, Real Time Clock, 16GB SD card, 5 I2C devices, acoustic alarms, has its own internal diagnostics, supports a web page for viewing status, logs, and reconfiguring over 40 parameters, synchs the RTC with the internet, is interfaced to a Victron solar charger, controls two separate 75 Watt loads, etc. etc. etc.
@SteveMann: Concerning AT commands, I agree but that is how the ESP-01 libraries typically function. I don't actually issue the AT commands, the library does it. I got it working, BUT... at 115200 plus the overhead of the AT commands and library, it just isn't very performant.
I am using an ESP board to provide WiFi because most of my projects include a multitude of sensors using I2C, a SPI SD card, a SPI monitor, multiple IO pins controlling LEDs, alarms, ... The 1284 has the power, but of course doesn't have WiFi. I suppose similar situations is exactly why Jiri wrote the WiFiSPI library.
Yes, I am attempting to design a 5V adapter on which the ESP, logic level conversion, power supply, the required "safe Reset", etc. If it works, I can plug it into a project as simple as I now plug in a SD card module or sensor. Creating a schematic is the first step to creating the PCB.
I could do that and maybe I should have said something about the labels I did use. Something like CS5 is the CS coming from the 5 Volt side. CS3 is the same signal on the 3.3 volt side. The logic converter only has VCC and ground other than the signals. The ESP pins I didn't use are things like the ADC, and unused IO pins.
Yes, really. Like I said, creating a schematic is the first step of creating the board.
Thanks a ton for your time and suggestions. Did my explanation clear up enough about the pins or should I go back and label all of them?
Normally port expanders are used, or I2C sensors which all use the same two pins of the ESP.
The BC807 NPN transistor should be a PNP transistor, The 1117 is missing decoupling caps,
that EN circuit should not be needed, because the ESP-12 has an EN pin.
The 2N2907 NPN is the wrong way round, no decoupling on the 74LVC supply, why the 3k3 resistors, should I go on?
Oops, the BC807 IS a pnp but I used the wrong part while drawing the circuit. I will correct that.
Ok, I can add 10µF on the VIn of 1117.
I have used a similar circuit with the 807 (except it was throughhole, this time I wanted SMT) thinking that the best way to save power is to shut the circuit down. You are right, the ESP has the EN pin for standby. I haven't used the ESP-12 before and was planning to break the EN pin out to see how much power everything would use in standby vs. power off. In retrospect, maybe I am being fanatic.
I think the 2907 is correct but I again used the wrong symbol in the schematics. The circuit itself is taken from a suggestion Jiri Bilek and others had incorporated into the library docs to allow the ESP to boot if the SPI Master has the CS pin high.
I can add 100nF on the 74LV.
I don't know why the 74LV has 3.3K on the input pins. The circuit was lifted from a manufactured SD Card Module and they are there.