ESP32 Forum

Hi,

I have a very peculiar bug. Sometimes my NFC PN532 reader, will cause the I2C bus on the ESP32 to completely freeze up. It will return [Wire.cpp:513] requestFrom(): i2cRead returned Error 263 permanently.

No flashing with working code, no power cycling, no nothing can resolve it. The I2C communciation is just stuck.

Then after letting the device rest for a day without power for a day or so, sometimes I can erase the flash and reflash and resolve the error. Sometimes, even then the board is still stuck.

So my first priority is to find a way to relibaly get the devices unstuck because most of the time I cannot try debug anything, while my whole stack of boards is stuck. Any ideas?

And secondly I'd like to understand what is causing it. Below code for example works. But if I just call the nfc function from a task instead of in loop, the error happens.

/**************************************************************************/
/*!
@file readntag203.pde
@author KTOWN (Adafruit Industries)
@license BSD (see license.txt)

This example will wait for any NTAG424 card or tag,
and will attempt to read the NDEF file from it.

*/
/**************************************************************************/
#define NTAG424DEBUG

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_PN532_NTAG424.h>
#include <PN532_I2C.h>
#include <PN532.h>
#include <NfcAdapter.h>

// If using the breakout with SPI, define the pins for SPI communication.
/*
#define PN532_SCK (18)
#define PN532_MOSI (23)
#define PN532_SS (5)
#define PN532_MISO (19)
*/
// NFC Pins

// If using the breakout with SPI, define the pins for SPI communication.
//#define PN532_SCK (17)
//#define PN532_MOSI (13)
//#define PN532_SS (15)
//#define PN532_MISO (12)


// This is optional to powerup/down the PN532-board.
// For RSTPD_N to work i had to desolder a 10k resistor between RSTPD_N and VCC
//#define PN532_RSTPD_N (2)

// If using the breakout or shield with I2C, define just the pins connected
// to the IRQ and reset lines. Use the values below (2, 3) for the shield!
#define NFC_SDA 13
#define NFC_SCL 15
#define NFC_IRQ 26
#define NFC_RST 25

Adafruit_PN532 *nfc = NULL;
PN532_I2C *pn532_i2c = NULL;
PN532 *pn532 = NULL;
NfcAdapter *nfcAdapter = NULL;

String lnurlwNFC = "";
bool isRfOff = false;
bool lnurlwFound = false;

// Uncomment just _one_ line below depending on how your breakout or shield
// is connected to the Arduino:

// Use this line for a breakout with a software SPI connection (recommended):
//Adafruit_PN532 nfc(PN532_SCK, PN532_MISO, PN532_MOSI, PN532_SS);

// Use this line for a breakout with a hardware SPI connection. Note that
// the PN532 SCK, MOSI, and MISO pins need to be connected to the Arduino's
// hardware SPI SCK, MOSI, and MISO pins. On an Arduino Uno these are
// SCK = 13, MOSI = 11, MISO = 12. The SS line can be any digital IO pin.
//Adafruit_PN532 nfc(PN532_SS);

// Or use this line for a breakout or shield with an I2C connection:

void scanDevices(TwoWire *w)
{
uint8_t err, addr;
int nDevices = 0;
uint32_t start = 0;
for (addr = 1; addr < 127; addr++) {
start = millis();
w->beginTransmission(addr); delay(2);
err = w->endTransmission();
delay(10);
if (err == 0) {
nDevices++;
String message = "[nfcTask] I2C device found at address 0x";
if (addr < 16) {
message += "0";
}
message += String(addr, HEX);
Serial.println(message);
break;

} else if (err == 4) {
String message = "[nfcTask] Unknown error at address 0x";
if (addr < 16) {
message += "0";
}
message += String(addr, HEX);
Serial.println(message);
}
}
if (nDevices == 0)
Serial.println("[nfcTask] No I2C devices found\n");
}

void setRFoff(bool turnOff, PN532_I2C* pn532_i2c) {
uint8_t commandRFoff[3] = {0x32, 0x01, 0x00}; // RFConfiguration command to turn off the RF field
uint8_t commandRFon[7] = { 0x02, 0x02, 0x00, 0xD4, 0x02, 0x2A, 0x00 };
// Check the desired state
if (turnOff && !isRfOff) {
Serial.println("[nfcTask] Powering down RF");
// Try to turn off RF
if (pn532_i2c->writeCommand(commandRFoff, sizeof(commandRFoff)) == 0) {
// If RF is successfully turned off, set the flag
Serial.println("[nfcTask] RF is off");
isRfOff = true;
Serial.println("[nfcTask] RF is off - Flag set");
} else {
Serial.println("[nfcTask] Error powering down RF");
}
} else if (!turnOff && isRfOff) {
Serial.println("[nfcTask] Powering up RF");
// Try to turn on RF
vTaskDelay(21);
if (pn532_i2c->writeCommand(commandRFon, sizeof(commandRFon)) == 0) {
// If RF is successfully turned on, clear the flag
Serial.println("[nfcTask] RF is on");
isRfOff = false;
} else {
Serial.println("[nfcTask] Error powering up RF");
ESP.restart();
}
} else {
Serial.println("[nfcTask] RF already in desired state");
}
}

void i2c_bus_reset(int sda_pin, int scl_pin) {
pinMode(sda_pin, OUTPUT); // set pins as output
pinMode(scl_pin, OUTPUT);

digitalWrite(sda_pin, 0); // produce I2C bus short circuit
digitalWrite(scl_pin, 0);

delay(10); // wait more than 5 ms

digitalWrite(sda_pin, 1); // stop forcing SDA and SCL to ground
digitalWrite(scl_pin, 1);
}

bool initNFC(PN532_I2C** pn532_i2c, Adafruit_PN532** nfc, PN532** pn532, NfcAdapter** nfcAdapter) {
pinMode(2, OUTPUT);
digitalWrite(2, HIGH);
// Initialize the IRQ pin as input
pinMode(NFC_IRQ, INPUT);
// Initialize the RST pin as output
pinMode(NFC_RST, OUTPUT);
// Set the RST pin to LOW to reset the module
digitalWrite(NFC_RST, LOW);
vTaskDelay(210);
// Set the RST pin to HIGH to finish the reset
digitalWrite(NFC_RST, HIGH);
// Initialize the I2C bus with the correct SDA and SCL pins
Wire.begin(NFC_SDA, NFC_SCL);
Wire.setClock(10000);
Wire.setTimeOut(2100);
// Initialize the PN532_I2C object with the initialized Wire object
*pn532_i2c = new PN532_I2C(Wire);
// Initialize the PN532 object with the initialized PN532_I2C object
*pn532 = new PN532(**pn532_i2c);
//initialize NFC Adapter object
*nfcAdapter = new NfcAdapter(**pn532_i2c);
// Initialize the Adafruit_PN532 object with the initialized PN532_I2C object
*nfc = new Adafruit_PN532(NFC_SDA, NFC_SCL);
// Use the pointer to call begin() and SAMConfig()
// Try to initialize the NFC reader
(*pn532)->begin();
(*pn532)->SAMConfig();
scanDevices(&Wire);
byte error = Wire.endTransmission();
if (error == 0) {
uint32_t versiondata = (*pn532)->getFirmwareVersion();
if (! versiondata) {
Serial.println("[nfcTask] Didn't find PN53x board");
return false;
}
// Got ok data, print it out!
String message = "[nfcTask] Found chip PN5" + String((versiondata >> 24) & 0xFF, HEX);
Serial.println(message.c_str());
message = "[nfcTask] Firmware ver. " + String((versiondata >> 16) & 0xFF, DEC);
Serial.println(message.c_str());
message = "[nfcTask] Firmware ver. " + String((versiondata >> 8) & 0xFF, DEC);
Serial.println(message.c_str());
setRFoff(true, *pn532_i2c);
return true;
} else {
String message = "[nfcTask] Wire error: " + String(error);
Serial.println(message.c_str());
return false;
}
}

bool isLnurlw(void) {
Serial.println("[nfcTask] Checking if URL is lnurlw");
if (lnurlwNFC.startsWith("lnurlw")) {
lnurlwNFC.replace("lnurlw", "https");
} else if (lnurlwNFC.startsWith("http") && !lnurlwNFC.startsWith("https")) {
lnurlwNFC.replace("http", "https");
}
// Check if the URL starts with "https://"
if (lnurlwNFC.startsWith("https://")) {
Serial.println("[nfcTask] URL is lnurlw");
return true;
} else {
Serial.println("[nfcTask] URL is not lnurlw");
return false;
}
}

bool readAndProcessNFCData(PN532_I2C *pn532_i2c, PN532 *pn532, Adafruit_PN532 *nfc, NfcAdapter *nfcAdapter, int &readAttempts)
{
NdefMessage message;
int recordCount;
uint8_t cardType = nfc->ntag424_isNTAG424();
if (cardType)
{
uint8_t data[256];
uint8_t bytesread = nfc->ntag424_ISOReadFile(data);
// Extract URL from data
lnurlwNFC = String((char*)data);
Serial.println("URL from NTAG424: " + lnurlwNFC);
if (isLnurlw())
{
while (!isRfOff)
{
setRFoff(true, pn532_i2c); // Attempt to switch off RF
}
lnurlwFound = true;
return true;
}
}
else
{
NfcTag tag = nfcAdapter->read();
String tagType = tag.getTagType();
Serial.println("[nfcTask] Tag type read");
Serial.println("Tag Type: " + tagType);
if (tag.hasNdefMessage())
{
message = tag.getNdefMessage();
recordCount = message.getRecordCount();
}
bool lnurlwFound = false;
for (int i = 0; i < recordCount && !lnurlwFound; i++)
{
NdefRecord record = message.getRecord(i);
String recordType = record.getType();
String logMessage = "Record Type: " + recordType;
Serial.println(logMessage);
if (recordType == "U" || recordType == "T")
{
uint8_t payload[record.getPayloadLength() + 1] = {0}; // Added +1 to the size and initialized to 0 to ensure null termination
record.getPayload(payload);
String recordPayload;
if (recordType == "U")
{
switch (payload[0])
{
case 0x01:
recordPayload = "http://www.";
break;
case 0x02:
recordPayload = "https://www.";
break;
case 0x03:
recordPayload = "http://";
break;
case 0x04:
recordPayload = "https://";
break;
default:
recordPayload = String((char*)payload);
break;
}
recordPayload += String((char*)&payload[1]);
}
else
{
for (int i = 0; i < record.getPayloadLength(); i++)
{
recordPayload += (char)payload;
}
}
lnurlwNFC = recordPayload;
String logMessage = "Record Payload: " + recordPayload;
Serial.println(logMessage);
if (isLnurlw())
{
while (!isRfOff)
{
setRFoff(true, pn532_i2c); // Attempt to switch off RF
}
lnurlwFound = true;
return true;
}
}
}
}
lnurlwNFC = ""; // Reset the global variable if it's not lnurlw
readAttempts++;
if (readAttempts >= 12)
{
setRFoff(true, pn532_i2c); // Switch off RF
if (isRfOff)
{
return false;
}
}
return false;
}

void setup(void) {
Serial.begin(115200);
while (!initNFC(&pn532_i2c, &nfc, &pn532, &nfcAdapter)) {
Serial.println("[nfcTask] Failed to initialize NFC");
}
setRFoff(false, pn532_i2c); // Switch on RF
}

void resetPN532() {
// Send command to put PN532 in low power mode
pn532->powerDownMode();

// Reset I2C bus
Wire.end();
delay(100); // Wait for 100 ms
Wire.begin();

// Reinitialize PN532
pn532->begin();
pn532->SAMConfig();
}

void loop(void) {
uint8_t success;
uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 }; // Buffer to store the returned UID
uint8_t uidLength; // Length of the UID (4 or 7 bytes depending on ISO14443A card type)

Serial.println("Waiting for tag...");
success = nfc->readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength, 420);

if (success) {
int readAttempts = 0;
bool cardRead = readAndProcessNFCData(pn532_i2c, pn532, nfc, nfcAdapter, readAttempts);
if (cardRead) {
Serial.println("Card read successfully.");
} else {
Serial.println("Failed to read card.");
}
}
}

Found the issue:

Adafruit_PN532 objects need the IRQ and RST pin. If this lib acceses the SDA and SCL pins directly then it confuses the PN532 beyond recognition.