esphome/esphome/components/sensirion_common/i2c_sensirion.cpp
2022-06-27 18:02:46 -03:00

128 lines
3.6 KiB
C++

#include "i2c_sensirion.h"
#include "esphome/core/log.h"
#include "esphome/core/hal.h"
#include <cinttypes>
namespace esphome {
namespace sensirion_common {
static const char *const TAG = "sensirion_i2c";
// To avoid memory allocations for small writes a stack buffer is used
static const size_t BUFFER_STACK_SIZE = 16;
bool SensirionI2CDevice::read_data(uint16_t *data, uint8_t len) {
const uint8_t num_bytes = len * 3;
std::vector<uint8_t> buf(num_bytes);
last_error_ = this->read(buf.data(), num_bytes);
if (last_error_ != i2c::ERROR_OK) {
return false;
}
for (uint8_t i = 0; i < len; i++) {
const uint8_t j = 3 * i;
uint8_t crc = sht_crc_(buf[j], buf[j + 1]);
if (crc != buf[j + 2]) {
ESP_LOGE(TAG, "CRC8 Checksum invalid at pos %d! 0x%02X != 0x%02X", i, buf[j + 2], crc);
last_error_ = i2c::ERROR_CRC;
return false;
}
data[i] = encode_uint16(buf[j], buf[j + 1]);
}
return true;
}
/***
* write command with parameters and insert crc
* use stack array for less than 4 parameters. Most sensirion i2c commands have less parameters
*/
bool SensirionI2CDevice::write_command_(uint16_t command, CommandLen command_len, const uint16_t *data,
uint8_t data_len) {
uint8_t temp_stack[BUFFER_STACK_SIZE];
std::unique_ptr<uint8_t[]> temp_heap;
uint8_t *temp;
size_t required_buffer_len = data_len * 3 + 2;
// Is a dynamic allocation required ?
if (required_buffer_len >= BUFFER_STACK_SIZE) {
temp_heap = std::unique_ptr<uint8_t[]>(new uint8_t[required_buffer_len]);
temp = temp_heap.get();
} else {
temp = temp_stack;
}
// First byte or word is the command
uint8_t raw_idx = 0;
if (command_len == 1) {
temp[raw_idx++] = command & 0xFF;
} else {
// command is 2 bytes
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
temp[raw_idx++] = command >> 8;
temp[raw_idx++] = command & 0xFF;
#else
temp[raw_idx++] = command & 0xFF;
temp[raw_idx++] = command >> 8;
#endif
}
// add parameters followed by crc
// skipped if len == 0
for (size_t i = 0; i < data_len; i++) {
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
temp[raw_idx++] = data[i] >> 8;
temp[raw_idx++] = data[i] & 0xFF;
#else
temp[raw_idx++] = data[i] & 0xFF;
temp[raw_idx++] = data[i] >> 8;
#endif
temp[raw_idx++] = sht_crc_(data[i]);
}
last_error_ = this->write(temp, raw_idx);
return last_error_ == i2c::ERROR_OK;
}
bool SensirionI2CDevice::get_register_(uint16_t reg, CommandLen command_len, uint16_t *data, uint8_t len,
uint8_t delay_ms) {
if (!this->write_command_(reg, command_len, nullptr, 0)) {
ESP_LOGE(TAG, "Failed to write i2c register=0x%X (%d) err=%d,", reg, command_len, this->last_error_);
return false;
}
delay(delay_ms);
bool result = this->read_data(data, len);
if (!result) {
ESP_LOGE(TAG, "Failed to read data from register=0x%X err=%d,", reg, this->last_error_);
}
return result;
}
// The 8-bit CRC checksum is transmitted after each data word
uint8_t SensirionI2CDevice::sht_crc_(uint16_t data) {
uint8_t bit;
uint8_t crc = 0xFF;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
crc ^= data >> 8;
#else
crc ^= data & 0xFF;
#endif
for (bit = 8; bit > 0; --bit) {
if (crc & 0x80) {
crc = (crc << 1) ^ crc_polynomial_;
} else {
crc = (crc << 1);
}
}
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
crc ^= data & 0xFF;
#else
crc ^= data >> 8;
#endif
for (bit = 8; bit > 0; --bit) {
if (crc & 0x80) {
crc = (crc << 1) ^ crc_polynomial_;
} else {
crc = (crc << 1);
}
}
return crc;
}
} // namespace sensirion_common
} // namespace esphome