OVMS3-idf/examples/ethernet/basic/README.md

Ethernet Example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

Overview

This example demonstrates basic usage of Ethernet driver together with tcpip_adapter. The work flow of the example could be as follows:

1. Install Ethernet driver
2. Send DHCP requests and wait for a DHCP lease
3. If get IP address successfully, then you will be able to ping the device

If you have a new Ethernet application to go (for example, connect to IoT cloud via Ethernet), try this as a basic template, then add your own code.

How to use example

Hardware Required

To run this example, it's recommended that you have an official ESP32 Ethernet development board - ESP32-Ethernet-Kit. This example should also work for 3rd party ESP32 board as long as it's integrated with a supported Ethernet PHY chip. Up until now, ESP-IDF supports four Ethernet PHY: LAN8720, IP101, DP83848 and RTL8201, additional PHY drivers should be implemented by users themselves.

Project configuration in menuconfig

Enter make menuconfig if you are using GNU Make based build system or enter idf.py menuconfig if you' are using CMake based build system.

1. In the Example Configuration menu:

• Choose PHY device under Ethernet PHY Device, by default, the ESP32-Ethernet-Kit has an IP101 on board.

2. In the Component config > Ethernet menu:

• Enable Use ESP32 internal EMAC controller, and then go into this menu.

• In the PHY interface, it's highly recommended that you choose Reduced Media Independent Interface (RMII) which will cost fewer pins.

• In the RMII clock mode, you can choose the source of RMII clock (50MHz): Input RMII clock from external or Output RMII clock from internal.

• Once Output RMII clock from internal is enabled, you also have to set the number of the GPIO used for outputting the RMII clock under RMII clock GPIO number. In this case, you can set the GPIO number to 16 or 17.

• Once Output RMII clock from GPIO0 (Experimental!) is enabled, then you have no choice but GPIO0 to output the RMII clock.

• Set SMI MDC/MDIO GPIO number according to board schematic, by default these two GPIOs are set as below:

  Default Example GPIO	RMII Signal	Notes
  GPIO23	MDC	Output to PHY
  GPIO18	MDIO	Bidirectional

• If you have connect a GPIO to the PHY chip's RST pin, then you need to enable Use Reset Pin of PHY Chip and set the GPIO number under PHY RST GPIO number.

Extra configuration in the code (Optional)

• By default Ethernet driver will assume the PHY address to 1, but you can alway reconfigure this value after eth_phy_config_t phy_config = ETH_PHY_DEFAULT_CONFIG();. The actual PHY address should depend on the hardware you use, so make sure to consult the schematic and datasheet.

Build and Flash

Enter make -j4 flash monitor if you are using GNU Make based build system or enter idf.py build flash monitor if you' are using CMake based build system.

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

I (336) cpu_start: Starting scheduler on PRO CPU.
I (0) cpu_start: Starting scheduler on APP CPU.
I (382) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (392) eth_example: Ethernet Started
I (3922) eth_example: Ethernet Link Up
I (5862) tcpip_adapter: eth ip: 192.168.2.151, mask: 255.255.255.0, gw: 192.168.2.2
I (5862) eth_example: Ethernet Got IP Address
I (5862) eth_example: ~~~~~~~~~~~
I (5862) eth_example: ETHIP:192.168.2.151
I (5872) eth_example: ETHMASK:255.255.255.0
I (5872) eth_example: ETHGW:192.168.2.2
I (5882) eth_example: ~~~~~~~~~~~

Troubleshooting

• RMII Clock

  • ESP32's MAC and the external PHY device need a common 50MHz reference clock (aka RMII clock). This clock can either be provided by an externally oscillator or generated from internal APLL. The signal integrity of RMII clock is strict, so it is highly recommended to add a 33Ω resistor in series to reduce possible ringing.
  • ESP32 can generate a 50MHz clock using internal APLL. But if the APLL is already used for other purposes (e.g. I2S peripheral), then you have no choice but use an external RMII clock.

• GPIO connections

  • RMII PHY wiring is fixed and can not be changed through either IOMUX or GPIO Matrix. They're described as below:

  GPIO	RMII Signal	ESP32 EMAC Function
  GPIO21	TX_EN	EMAC_TX_EN
  GPIO19	TX0	EMAC_TXD0
  GPIO22	TX1	EMAC_TXD1
  GPIO25	RX0	EMAC_RXD0
  GPIO26	RX1	EMAC_RXD1
  GPIO27	CRS_DV	EMAC_RX_DRV

(For any technical queries, please open an issue on GitHub. We will get back to you as soon as possible.)