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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:
- Install Ethernet driver
- Send DHCP requests and wait for a DHCP lease
- 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.
- In the
Example Configuration
menu:
- Choose PHY device under
Ethernet PHY Device
, by default, the ESP32-Ethernet-Kit has anIP101
on board.
- 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 chooseReduced 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
orOutput 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 underRMII 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 underPHY 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 aftereth_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.)