RFid click

RFid click features CR95HF 13.56 MHz contactless transceiver as well as trace antenna. The click is designed to run on a 3.3V power supply only. It communicates with the target MCU via mikroBUS™ UART (TX, RX), SPI (MISO, MOSI, SCK, CS) INT, RST, PWM and AN lines.

The click functions as an integrated transceiver for contactless applications. The board contains a dedicated internal frame controller and analog front end (AFE) for RF communications. It supports ISO/IEC 14443 type A and B, ISO/IEC 15693 and ISO/IEC 18092 protocols (tags) as well as the detection, reading and writing of NFC forum type 1, 2, 3 and 4 tags.

CR95HF integrated transceiver

The CR95HF has 2 operating modes: Wait for Event (WFE) and Active.

In Active mode, the CR95HF communicates actively with a tag or an external host. WFE mode includes four low consumption states: Power-up, Hibernate, Sleep and Tag Detector. The transceiver can switch from one mode to another.

The Hibernate state has the lowest power consumption out of the four states (1 µA typ. 5 µA max.).

SMD jumpers

Two SMD jumpers are provided on the board. In case you want to use UART interface, it is necessary to solder SMD jumpers in B position. Otherwise, if you want to use SPI interface, jumpers should be left in its default position (A). In that case interrupt pins (IN and OUT) are usable.

Key features

• CR95HF IC
  • Operating modes supported: Reader/Writer
  • RF communication @13.56 MHz
  • Supports NFC Forum Type 1, 2, 3 and 4 tags
• 3.3V power supply
• Interface: UART, SPI

Specification

Pinout diagram

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

Notes	Pin	mikroBUStm				Pin	Notes
Select serial communication interface	SSI1	1	AN	PWM	16	INT_I	Interrupt input
Select serial communication interface	SSI0	2	RST	INT	15	INT_O	Interrupt output
SPI chip select	CS#	3	CS	TX	14	TX	UART transmit
SPI clock	SCK	4	SCK	RX	13	RX	UART receive
SPI Data, Slave Output	MISO	5	MISO	SCL	12	NC	Not connected
SPI Data, Slave Input	MOSI	6	MOSI	SDA	11	NC	Not connected
Power supply	+3.3V	7	3.3V	5V	10	NC	Not connected
Ground	GND	8	GND	GND	9	GND	Ground

Programming

Code examples that demonstrate the usage of RFID click with MikroElektronika hardware, written for mikroC for ARM, AVR, dsPIC, FT90x, PIC and PIC32 are available on Libstock.

The following code snippet uses a TFT to communicate with the user when the click is ready for reading and afterwards tells the user what the Tag ID is.

 1 void main() {
2 Init(); // Initialize MCU and peripherals
3 DrawFrame();
4 while (!EchoResponse()) { // Until CR95HF is detected
5 IRQ_IN = 1; // put IRQ_IN pin at low level
6 delay_ms(1);
7 IRQ_IN = 0; // put IRQ_IN pin at low level
8 delay_ms(1);
9 }
10 TFT_Write_Text("CR95HF Device Connected.", 55, 60);
11 
12 ReadCR95HF_ID();
13 Calibration();
14 IndexMod_Gain();
15 AutoFDet();
16 Select_ISO_IEC_18092_Protocol();
17 
18 while (1) {
19 if (!TAG_Flag)
20 GetNFCTag(); // Get NFC ID
21 
22 if (!NFC_Flag)
23 GetTagID(); // Get Tag ID
24 
25 if (ID[0] == 0) { // If there is no tag present
26 flag++; // Increment counter flag
27 }
28 else { // If tag is present
29 flag = 0; // Reset counter flag
30 if (strcmp(ID_old, ID)) { // Compare previous and current tag ID
31 TFT_Set_Font(TFT_defaultFont, CL_WHITE, FO_HORIZONTAL); // Set font color to white
32 TFT_Write_Text(ID_old, x_pos_old, 180); // Delete previous tag ID
33 TFT_Set_Font(TFT_defaultFont, CL_RED, FO_HORIZONTAL); // Set font color to red
34 TFT_Write_Text("Tag ID :", 130, 160);
35 TFT_Write_Text(ID, x_pos, 180); // Display current tag ID
36 TFT_Set_Font(TFT_defaultFont, CL_WHITE, FO_HORIZONTAL); // Set font color to white
37 TFT_Write_Text("Put the RFid Tag over the RFid Click Antenna", 25, 140);
38 strcpy(ID_old, ID); // Set current ID as previous ID
39 Delay_ms(2000);
40 x_pos_old = x_pos;
41 }
42 }
43 if (flag > 5) { // If counter flag has reached value > 5
44 TFT_Set_Font(TFT_defaultFont, CL_BLACK, FO_HORIZONTAL); // Set font color to black
45 TFT_Write_Text("Put the RFid Tag over the RFid Click Antenna", 25, 140);
46 TFT_Set_Font(TFT_defaultFont, CL_WHITE, FO_HORIZONTAL); // Set font color to white
47 TFT_Write_Text("Tag ID :", 130, 160);
48 TFT_Write_Text(ID_old, x_pos_old, 180); // Delete previous tag ID
49 ID_old[0] = 0; // Terminate the old ID string
50 flag = 0; // Reset counter flag
51 }
52 ID[0] = 0; // Terminate the ID string
53 
54 // Clear read and write buffers
55 for (j = 0; j < 18; j++) {
56 rdata[j] = 0;
57 sdata[j] = 0;
58 }
59 }
60 }