HOW DOES IT WORK?

RS Transceiver Click is based on the XR34350, an RS-232/RS-422/RS-485 serial transceiver with internal termination and wide output swing from MaxLinear. It is an advanced multiprotocol transceiver with dual protocol serial ports, RS-232 or RS-485/RS-422. The RS-485/RS-422 modes feature one driver and one receiver (1TX/1RX) in both half and full duplex configurations, where high-speed drivers operate up to 20Mbps. The RS-485 and RS-422 are both 2-Wire protocols, where the RS-485 can have multiple commanding devices and listeners. On the other hand, the RS-422 can have only one commander and multiple listeners.

The RS-232 mode features three drivers and five receivers (3TX/5RX) and provides full support for all eight signals. In the RS-232 mode, it can achieve data rates up to 1Mbps. All transceiver drivers can be slew limited to 250Kbps in any mode, thus minimizing electromagnetic interference. The XR34350 eliminates the need to design a termination resistor when sharing a single connector or a pair of lines across multiple serial protocols. It integrates the terminal resistor and switching control, thus allowing it to be switched in and out of the circuit with a single pin. The RS-485/RS-422 receiver inputs are high impedance, while the RS-232 receiver input is pulled-down, allowing up to 256 devices on a single communication bus.

The RS Transceiver uses a standard UART interface to communicate with the host MCU, with commonly used UART RX and TX. In addition, the UART flow control pins CTS and RTS are available on the mikroBUS™ socket. The transceiver can be reset over the RST pin, and limiting can be activated over the SLW pin.

As the mikroBUS™ socket is pin-limited, the RS Transceiver includes the TCA9536, a remote 4-bit IO expander with configuration registers from Texas Instruments, bringing an additional four I/Os to the host MCU. The TCA9536 communicates with the host MCU over the standard I2C serial interface supporting fast mode up to 1MHz. Using this I/O expander, you can set half-duplex or full-duplex mode over the DIR1 pin of the transceiver. There are two mode pins, MODE0 and MODE1, that you can use to select one mode between Loopback Mode, Half-Duplex RS-485 Mode #1, RS-232 Mode, and Full-Duplex RS-485/422 Mode #1. The Term pin only applies in the half-duplex and full-duplex RS-485/RS-422 modes as it enables the internal termination resistor.

There are two additional headers on this Click board™. The lower one brings GND, L1, L4, L6, and L9 pins from the transceiver, and the RS-485 signals are also available on the upper header for testing purposes of the full and half duplex modes. These signals are also available on the DE-9 connector.

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.

SPECIFICATIONS