How does it work?

ETH Click is based on the ENC28J60, a stand-alone Ethernet controller with an industry-standard Serial Peripheral Interface (SPI) from Microchip, designed in Half-Duplex Mode to serve as an Ethernet network interface for any host MCU. The ENC28J60 consists of seven major functional parts such as a serial interface and control register block, a dual port RAM buffer for received and transmitted data packets, the MAC (Medium Access Control) module that implements IEEE 802.3 compliant MAC logic, and the PHY (Physical Layer) module that encodes and decodes the analog data that is present on the twisted-pair interface through an onboard RJ-45 connector.

This Click board™ communicates with MCU through a standard SPI interface supporting the most common SPI mode, SPI Mode 0, with a maximum frequency of 20MHz. The operation of the ENC28J60 depends entirely on commands given by the host MCU over the SPI interface in the form of instructions of one or more bytes used to access the control memory and Ethernet buffer spaces. The entire buffer is 8 Kbytes, divided into separate receive and transmit buffer spaces used by the Ethernet controller.

Before the ENC28J60 can be used to transmit and receive packets, specific settings must be initialized. Depending on the application, some configurational options must change. These tasks may be accomplished once after Reset, activated through the RST pin of the mikroBUS™ socket. The ENC28J60 also uses an interrupt pin, the INT pin of the mikroBUS™ socket, to signal the occurrence of events to the host MCU alongside two LED indicators, green for a link and yellow for network activity indication.

Apart from these indications, these LEDs also support automatic polarity detection during a Reset case. Upon system Reset, the ENC28J60 will detect how the LED is connected and begin driving the LED to the default state configured by the PHLCON register. If the LED polarity changes while the ENC28J60 operates, there will be no new polarity detection until the next system Reset occurs. The LEDs can also be configured separately to control their operating polarity (ON or OFF when active), blink rate, and blink stretch interval.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Specifications

Pinout diagram

This table shows how the pinout on ETH Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Onboard settings and indicators

ETH Click electrical specifications