RS485 2 click

MAX3471 transceiver features

The MAX3471 draws only 1.6µA (typical) supply current from a 3.6V supply with the receiver enabled and the driver disabled. Its wide 2.5V to 5.5V supply voltage guarantees operation over the lifetime of a lithium battery.

This device contains one driver and one receiver. Its true fail-safe receiver input guarantees a logic-high receiver output when the receiver inputs are open or shorted, or when they are connected to a terminated transmission line with all drivers disabled.

The MAX3471 receiver operates at up to 64kbps and incorporates input filtering in addition to input hysteresis. This filtering enhances noise immunity when differential signals have very slow rise and fall times.

How the click works

There are two pairs of screw terminals on board the RS485 2 click. The ones marked with A and B are differential high and differential low communication lines. We added two more terminals for VCC and GND reference if needed for further interfacing.

Specifications

Pinout diagram

This table shows how the pinout on RS485 2 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	RE	Receiver output enable, active low
	NC	2	RST	INT	15	NC
Driver output enable, active high	DE	3	CS	TX	14	RX	UART data receive
	NC	4	SCK	RX	13	TX	UART data transmit
	NC	5	MISO	SCL	12	NC
	NC	6	MOSI	SDA	11	NC
Power supply	+3.3V	7	3.3V	5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

Jumpers and settings

Programming

Code examples for RS485 2 click, written for MikroElektronika hardware and compilers are available on Libstock.

Code snippet

The following code snippet shows a part of the RS485 2 click example. One device is set as the slave, and the other is the master. Upon button press on the master, an LED light on the slave device will change its state.

01 void main()
02 {
03 systemInit();
04 
05 while( 1 )
06 {
07 #ifdef MASTER_NODE
08 if (isButtonPressed())
09 {
10 ledToggle();
11 RS485_2_transmit(&cmd, 1);
12 }
13 Delay_ms(25);
14 #endif
15 }
16 }
17 
18 #ifdef SLAVE_NODE 
19 void RX_ISR() iv IVT_INT_USART3 ics ICS_AUTO
20 {
21 if( RXNE_USART3_SR_bit )
22 {
23 char rxByte = USART3_DR;
24 
25 if (rxByte == ON_CMD)
26 {
27 LED_PIN = LED_ON;
28 }
29 else if (rxByte == OFF_CMD)
30 {
31 LED_PIN = LED_OFF;
32 }
33 }
34 }

Downloads

LibStock: RS485 2 click library