PN532_I2C.cpp
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#include "PN532_I2C.h"
#include "PN532_debug.h"
#include "Arduino.h"
#define PN532_I2C_ADDRESS (0x48 >> 1)
PN532_I2C::PN532_I2C(TwoWire &wire)
{
_wire = &wire;
command = 0;
}
void PN532_I2C::begin()
{
_wire->begin();
}
void PN532_I2C::wakeup()
{
_wire->beginTransmission(PN532_I2C_ADDRESS); // I2C start
delay(20);
_wire->endTransmission(); // I2C end
}
int8_t PN532_I2C::writeCommand(const uint8_t *header, uint8_t hlen, const uint8_t *body, uint8_t blen)
{
command = header[0];
_wire->beginTransmission(PN532_I2C_ADDRESS);
write(PN532_PREAMBLE);
write(PN532_STARTCODE1);
write(PN532_STARTCODE2);
uint8_t length = hlen + blen + 1; // length of data field: TFI + DATA
write(length);
write(~length + 1); // checksum of length
write(PN532_HOSTTOPN532);
uint8_t sum = PN532_HOSTTOPN532; // sum of TFI + DATA
DMSG("write: ");
for (uint8_t i = 0; i < hlen; i++) {
if (write(header[i])) {
sum += header[i];
DMSG_HEX(header[i]);
} else {
DMSG("\nToo many data to send, I2C doesn't support such a big packet\n"); // I2C max packet: 32 bytes
return PN532_INVALID_FRAME;
}
}
for (uint8_t i = 0; i < blen; i++) {
if (write(body[i])) {
sum += body[i];
DMSG_HEX(body[i]);
} else {
DMSG("\nToo many data to send, I2C doesn't support such a big packet\n"); // I2C max packet: 32 bytes
return PN532_INVALID_FRAME;
}
}
uint8_t checksum = ~sum + 1; // checksum of TFI + DATA
write(checksum);
write(PN532_POSTAMBLE);
_wire->endTransmission();
DMSG('\n');
return readAckFrame();
}
int16_t PN532_I2C::readResponse(uint8_t buf[], uint8_t len, uint16_t timeout)
{
uint16_t time = 0;
do {
if (_wire->requestFrom(PN532_I2C_ADDRESS, len + 2)) {
if (read() & 1) { // check first byte --- status
break; // PN532 is ready
}
}
delay(1);
time++;
if ((0 != timeout) && (time > timeout)) {
return -1;
}
} while (1);
if (0x00 != read() || // PREAMBLE
0x00 != read() || // STARTCODE1
0xFF != read() // STARTCODE2
) {
return PN532_INVALID_FRAME;
}
uint8_t length = read();
if (0 != (uint8_t)(length + read())) { // checksum of length
return PN532_INVALID_FRAME;
}
uint8_t cmd = command + 1; // response command
if (PN532_PN532TOHOST != read() || (cmd) != read()) {
return PN532_INVALID_FRAME;
}
length -= 2;
if (length > len) {
return PN532_NO_SPACE; // not enough space
}
DMSG("read: ");
DMSG_HEX(cmd);
uint8_t sum = PN532_PN532TOHOST + cmd;
for (uint8_t i = 0; i < length; i++) {
buf[i] = read();
sum += buf[i];
DMSG_HEX(buf[i]);
}
DMSG('\n');
uint8_t checksum = read();
if (0 != (uint8_t)(sum + checksum)) {
DMSG("checksum is not ok\n");
return PN532_INVALID_FRAME;
}
read(); // POSTAMBLE
return length;
}
int8_t PN532_I2C::readAckFrame()
{
const uint8_t PN532_ACK[] = {0, 0, 0xFF, 0, 0xFF, 0};
uint8_t ackBuf[sizeof(PN532_ACK)];
DMSG("wait for ack at : ");
DMSG(millis());
DMSG('\n');
uint16_t time = 0;
do {
if (_wire->requestFrom(PN532_I2C_ADDRESS, sizeof(PN532_ACK) + 1)) {
if (read() & 1) { // check first byte --- status
break; // PN532 is ready
}
}
delay(1);
time++;
if (time > PN532_ACK_WAIT_TIME) {
DMSG("Time out when waiting for ACK\n");
return PN532_TIMEOUT;
}
} while (1);
DMSG("ready at : ");
DMSG(millis());
DMSG('\n');
for (uint8_t i = 0; i < sizeof(PN532_ACK); i++) {
ackBuf[i] = read();
}
if (memcmp(ackBuf, PN532_ACK, sizeof(PN532_ACK))) {
DMSG("Invalid ACK\n");
return PN532_INVALID_ACK;
}
return 0;
}