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Start with ESP32 Wrover

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Javert

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I want to try a project with ESP32, more precisely with ESP32-Wrover-ie
I'm looking at the documentation and I'm a little confused.

1. esp32-wrover-e_esp32-wrover-ie_datasheet_en.pdf Figure 7: Peripheral Schematics
IO12 should be kept low when the module is powered on
For God's sake why? I want to use the pin as SPI_MISO and nowhere else am i having a problem with IO12.

2. The same image and text below it
To ensure the power supply to the ESP32 chip during power-up, it is advised to add an RC delay circuit at the EN pin.
The recommended setting for the RC delay circuit is usually R = 10 kΩ and C = 1 μF
I understand the meaning, but I don't understand why C 100nF is used in the esp32-devkitc-v4_reference_design documentation?

3. Ethernet interface
due to the number of pins I want to use SPI MAC / PHY IC
esp-idf seems to support DM9051, W5500 and KSZ8851SNL directly (it is offered by the configuration program), but ENC28J60 is also included in the examples. How is it? I have a module with ENC28J60 on hand, I would have to order a module with W5500.

4.There is something like Getting started with ESP32 Wrover?
I don't want a world-class, basic recommended hw connection, maybe an example of using it with SPI

ESP32.jpg
 

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The reason for keeping some pins at particular logic levels is given in the "strapping" description on the data sheet. Basically, at power-up (and no other time) the states of some pins is checked to decide the operating mode, assuming it is in normal running mode, the pin can then be assigned for other uses. The other modes are for loading the firmware and for enabling or disabling serial boot messages from the UART.

The EN pin is for practical purposes, the reset input, it has to be kept low when the power is applied for long enough for the internal clock to stabilize. The time constant of 10K/0.1uF will be long enough if the power supply ramp time limit is observed.

You can use the ENC28J60 if you wish, it should work fine, if it doesn't have a driver in the library you are using there is no reason not to write your own routines or even create your own library.

There is a book called "Kolban's book on ESP32" which you might find useful, you can download it for a small fee but looking at example programs and the code inside libraries is also a good source of information.

Brian.
 

Hi,

For God's sake why? I want to use the pin as SPI_MISO and nowhere else am i having a problem with IO12.
Connect a pull-down .. and use it as MISO. That´s it.
(Be sure no other device pulls it UP during power up)

Klaus
 

I have a module with ENC28J60 on hand, I would have to order a module with W5500.
The tiny contact I had with both made me conclude that the W5500 has a simplest usage than the ENC28J60, and that would be my personal choice.
 

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