pn532_spi.cpp

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#include "pn532_spi.h"
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"
 
#include <array>
 
// Based on:
// - https://cdn-shop.adafruit.com/datasheets/PN532C106_Application+Note_v1.2.pdf
// - https://www.nxp.com/docs/en/nxp/application-notes/AN133910.pdf
// - https://www.nxp.com/docs/en/nxp/application-notes/153710.pdf
 
namespace esphome::pn532_spi {
 
static const char *const TAG = "pn532_spi";
 
// Maximum bytes to log in verbose hex output
static constexpr size_t PN532_MAX_LOG_BYTES = 64;
 
void PN532Spi::setup() {
  this->spi_setup();
 
  this->cs_->digital_write(false);
  delay(10);
  PN532::setup();
}
 
bool PN532Spi::is_read_ready() {
  this->enable();
  this->write_byte(0x02);
  // only bit 0 (RDY) of the status byte is defined (UM0701-02, 6.2.5)
  const bool ready = this->read_byte() & 0x01;
  this->disable();
  return ready;
}
 
bool PN532Spi::write_data(const std::span<const uint8_t> data) {
  this->enable();
  delay(2);
  // First byte, communication mode: Write data
  this->write_byte(0x01);
#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
  char hex_buf[format_hex_pretty_size(PN532_MAX_LOG_BYTES)];
#endif
  ESP_LOGV(TAG, "Writing data: %s", format_hex_pretty_to(hex_buf, sizeof(hex_buf), data.data(), data.size()));
  this->write_array(data.data(), data.size());
  this->disable();
 
  return true;
}
 
bool PN532Spi::read_data(pn532::PN532Frame &data, size_t len) {
  if (len + 1 > pn532::PN532_FRAME_MAX_SIZE || this->read_ready_(true) != pn532::PN532ReadReady::READY) {
    return false;
  }
 
  // Read data (transmission from the PN532 to the host)
  this->enable();
  delay(2);
  this->write_byte(0x03);
 
  ESP_LOGV(TAG, "Reading data");
 
  // lead with a status byte so callers see the same layout as on the I2C bus
  data.resize(len + 1);
  data[0] = 0x01;
  this->read_array(data.data() + 1, len);
  this->disable();
#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
  char hex_buf[format_hex_pretty_size(PN532_MAX_LOG_BYTES)];
#endif
  ESP_LOGV(TAG, "Read data: %s", format_hex_pretty_to(hex_buf, sizeof(hex_buf), data.data(), data.size()));
  return true;
}
 
bool PN532Spi::read_response(uint8_t command, pn532::PN532Frame &data) {
  ESP_LOGV(TAG, "Reading response");
 
  if (this->read_ready_(true) != pn532::PN532ReadReady::READY) {
    return false;
  }
 
  this->enable();
  delay(2);
  this->write_byte(0x03);
 
  std::array<uint8_t, 7> header;
  this->read_array(header.data(), header.size());
 
#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
  char hex_buf[format_hex_pretty_size(PN532_MAX_LOG_BYTES)];
#endif
  ESP_LOGV(TAG, "Header data: %s", format_hex_pretty_to(hex_buf, sizeof(hex_buf), header.data(), header.size()));
 
  if (header[0] != 0x00 || header[1] != 0x00 || header[2] != 0xFF) {
    // invalid packet
    ESP_LOGV(TAG, "read data invalid preamble!");
    this->disable();
    return false;
  }
 
  bool valid_header = (static_cast<uint8_t>(header[3] + header[4]) == 0 &&  // LCS, len + lcs = 0
                       header[5] == 0xD5 &&        // TFI - frame from PN532 to system controller
                       header[6] == command + 1);  // Correct command response
 
  if (!valid_header) {
    ESP_LOGV(TAG, "read data invalid header!");
    this->disable();
    return false;
  }
 
  // full length of message, including command response (minimum 2: TFI + command response)
  uint8_t full_len = header[3];
  if (full_len < 2) {
    ESP_LOGV(TAG, "read data has no payload");
    this->disable();
    return false;
  }
 
  // length of data, excluding command response
  uint8_t len = full_len - 1;
 
  ESP_LOGV(TAG, "Reading response of length %d", len);
 
  data.resize(len + 1);
  this->read_array(data.data(), len + 1);
  this->disable();
 
  ESP_LOGV(TAG, "Response data: %s", format_hex_pretty_to(hex_buf, sizeof(hex_buf), data.data(), data.size()));
 
  uint8_t checksum = header[5] + header[6];  // TFI + Command response code
  for (int i = 0; i < len - 1; i++) {
    uint8_t dat = data[i];
    checksum += dat;
  }
  checksum = ~checksum + 1;
 
  if (data[len - 1] != checksum) {
    ESP_LOGV(TAG, "read data invalid checksum! %02X != %02X", data[len - 1], checksum);
    return false;
  }
 
  if (data[len] != 0x00) {
    ESP_LOGV(TAG, "read data invalid postamble!");
    return false;
  }
 
  data.resize(len - 1);  // Remove checksum and postamble
 
  return true;
}
 
void PN532Spi::dump_config() {
  PN532::dump_config();
  LOG_PIN("  CS Pin: ", this->cs_);
}
 
}  // namespace esphome::pn532_spi