I'm a newbie to NFC and am using a Sparkfun ST25DV64KC. My microcontroller is a ESP32 (Firebeetle). I'm using the ST25DV64KC Arduino Library provide by sparkfun and specifically I'm starting with "Example 10-NDEF_Text" Listed below. On my apple phone I'm using the NFC_tools app. Everything works correctly when I upload and then use NFC_tools to read the text record/s.
What I'm wanting to do, and cannot figure it out, is instead of in the payload of the record display Hex values, instead I would like to display a string of text (perhaps using an char array) followed by the current value of a variable in my program, something like the following:
Days user has taken their medication = 3
where "Days user has taken their medication" is the string and 3 is the variable. I do not need to store the string or the variable in eeprom. Using the Example 10-NDEF_Text as a basis, can someone give me guidance on how to do this?
/*
ST25DV64KC Example
By: Ricardo Ramos and Paul Clark
SparkFun Electronics
Date: August, 2022
License: MIT. Please see the license file for more information but you can
basically do whatever you want with this code.
This example shows how to set up the ST25DV64KC's Capability Container (CC)
and create a NDEF UTF-8 Text record
Feel like supporting open source hardware?
Buy a board from SparkFun!
SparkFun Qwiic RFID Tag - ST25DV64KC : https://www.sparkfun.com/products/19035
Hardware Connections:
Plug a Qwiic cable into the Qwiic RFID Tag and a RedBoard
If you don't have a platform with a Qwiic connection use the SparkFun Qwiic Breadboard Jumper (https://www.sparkfun.com/products/14425)
Open the serial monitor at 115200 baud to see the output
*/
#include <SparkFun_ST25DV64KC_Arduino_Library.h> // Click here to get the library: http://librarymanager/All#SparkFun_ST25DV64KC
SFE_ST25DV64KC_NDEF tag;
void setup()
{
delay(1000);
Serial.begin(115200);
Wire.begin();
Serial.println(F("ST25DV64KC example."));
if (!tag.begin(Wire))
{
Serial.println(F("ST25 not detected. Freezing..."));
while (1) // Do nothing more
;
}
Serial.println(F("ST25 connected."));
// -=-=-=-=-=-=-=-=-
// The previous examples will have left the memory write-enabled.
// We should not need to open a security session here...
/*
Serial.println(F("Opening I2C security session with default password (all zeros)."));
uint8_t password[8] = {0x0}; // Default password is all zeros
tag.openI2CSession(password);
Serial.print(F("I2C session is "));
Serial.println(tag.isI2CSessionOpen() ? "opened." : "closed.");
*/
// -=-=-=-=-=-=-=-=-
// Clear the first 256 bytes of user memory
uint8_t tagMemory[256];
memset(tagMemory, 0, 256);
Serial.println("Writing 0x0 to the first 256 bytes of user memory.");
tag.writeEEPROM(0x0, tagMemory, 256);
// -=-=-=-=-=-=-=-=-
// Write the Type 5 CC File - starting at address zero
Serial.println(F("Writing CC_File"));
tag.writeCCFile8Byte();
// -=-=-=-=-=-=-=-=-
// Write two NDEF UTF-8 Text records
uint16_t memLoc = tag.getCCFileLen();
Serial.println(F("Writing the first NDEF Text record"));
tag.writeNDEFText("Hello, World!", &memLoc, true, false); // MB=1, ME=0
Serial.println(F("Writing the second NDEF Text record"));
tag.writeNDEFText("All your base are belong to us", &memLoc, false, true); // MB=0, ME=1
// -=-=-=-=-=-=-=-=-
// Read back the second NDEF UTF-8 Text record
Serial.println(F("Reading the second NDEF Text record:"));
char theText[40];
if (tag.readNDEFText(theText, 40, 2))
Serial.println(theText);
else
Serial.println(F("Read failed!"));
// -=-=-=-=-=-=-=-=-
// Read back the memory contents
Serial.println(F("The first 256 bytes of user memory are:"));
tag.readEEPROM(0x0, tagMemory, 256);
prettyPrintChars(tagMemory, 256);
}
void loop()
{
// Nothing to do here
}
void prettyPrintChars(uint8_t *theData, int theLength) // Pretty-print char data in HEX and ASCII format
{
Serial.println();
for (int i = 0; i < theLength; i += 16)
{
if (i < 10000)
Serial.print(F("0"));
if (i < 1000)
Serial.print(F("0"));
if (i < 100)
Serial.print(F("0"));
if (i < 10)
Serial.print(F("0"));
Serial.print(i);
Serial.print(F(" 0x"));
if (i < 0x1000)
Serial.print(F("0"));
if (i < 0x100)
Serial.print(F("0"));
if (i < 0x10)
Serial.print(F("0"));
Serial.print(i, HEX);
Serial.print(F(" "));
int j;
for (j = 0; ((i + j) < theLength) && (j < 16); j++)
{
if (theData[i + j] < 0x10)
Serial.print(F("0"));
Serial.print(theData[i + j], HEX);
Serial.print(F(" "));
}
if (((i + j) == theLength) && (j < 16))
{
for (int k = 0; k < (16 - (theLength % 16)); k++)
{
Serial.print(F(" "));
}
}
for (j = 0; ((i + j) < theLength) && (j < 16); j++)
{
if ((theData[i + j] >= 0x20) && (theData[i + j] <= 0x7E))
Serial.write(theData[i + j]);
else
Serial.print(F("."));
}
Serial.println();
}
Serial.println();
}