102 lines
3.2 KiB
C++
102 lines
3.2 KiB
C++
#include "i2c_sensirion.h"
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#include "esphome/core/hal.h"
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#include "esphome/core/helpers.h"
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#include "esphome/core/log.h"
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#include <cinttypes>
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namespace esphome {
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namespace sensirion_common {
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static const char *const TAG = "sensirion_i2c";
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// To avoid memory allocations for small writes a stack buffer is used
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static const size_t BUFFER_STACK_SIZE = 16;
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bool SensirionI2CDevice::read_data(uint16_t *data, const uint8_t len) {
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const uint8_t num_bytes = len * 3;
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uint8_t buf[num_bytes];
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this->last_error_ = this->read(buf, num_bytes);
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if (this->last_error_ != i2c::ERROR_OK) {
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return false;
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}
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for (uint8_t i = 0; i < len; i++) {
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const uint8_t j = 3 * i;
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// Use MSB first since Sensirion devices use CRC-8 with MSB first
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uint8_t crc = crc8(&buf[j], 2, 0xFF, CRC_POLYNOMIAL, true);
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if (crc != buf[j + 2]) {
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ESP_LOGE(TAG, "CRC invalid @ %d! 0x%02X != 0x%02X", i, buf[j + 2], crc);
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this->last_error_ = i2c::ERROR_CRC;
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return false;
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}
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data[i] = encode_uint16(buf[j], buf[j + 1]);
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}
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return true;
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}
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/***
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* write command with parameters and insert crc
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* use stack array for less than 4 parameters. Most Sensirion I2C commands have less parameters
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*/
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bool SensirionI2CDevice::write_command_(uint16_t command, CommandLen command_len, const uint16_t *data,
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const uint8_t data_len) {
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uint8_t temp_stack[BUFFER_STACK_SIZE];
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std::unique_ptr<uint8_t[]> temp_heap;
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uint8_t *temp;
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size_t required_buffer_len = data_len * 3 + 2;
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// Is a dynamic allocation required ?
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if (required_buffer_len >= BUFFER_STACK_SIZE) {
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temp_heap = std::unique_ptr<uint8_t[]>(new uint8_t[required_buffer_len]);
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temp = temp_heap.get();
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} else {
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temp = temp_stack;
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}
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// First byte or word is the command
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uint8_t raw_idx = 0;
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if (command_len == 1) {
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temp[raw_idx++] = command & 0xFF;
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} else {
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// command is 2 bytes
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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temp[raw_idx++] = command >> 8;
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temp[raw_idx++] = command & 0xFF;
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#else
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temp[raw_idx++] = command & 0xFF;
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temp[raw_idx++] = command >> 8;
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#endif
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}
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// add parameters followed by crc
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// skipped if len == 0
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for (size_t i = 0; i < data_len; i++) {
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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temp[raw_idx++] = data[i] >> 8;
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temp[raw_idx++] = data[i] & 0xFF;
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#else
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temp[raw_idx++] = data[i] & 0xFF;
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temp[raw_idx++] = data[i] >> 8;
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#endif
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// Use MSB first since Sensirion devices use CRC-8 with MSB first
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uint8_t crc = crc8(&temp[raw_idx - 2], 2, 0xFF, CRC_POLYNOMIAL, true);
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temp[raw_idx++] = crc;
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}
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this->last_error_ = this->write(temp, raw_idx);
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return this->last_error_ == i2c::ERROR_OK;
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}
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bool SensirionI2CDevice::get_register_(uint16_t reg, CommandLen command_len, uint16_t *data, const uint8_t len,
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const uint8_t delay_ms) {
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if (!this->write_command_(reg, command_len, nullptr, 0)) {
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ESP_LOGE(TAG, "Write failed: reg=0x%X (%d) err=%d,", reg, command_len, this->last_error_);
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return false;
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}
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delay(delay_ms);
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bool result = this->read_data(data, len);
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if (!result) {
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ESP_LOGE(TAG, "Read failed: reg=0x%X err=%d,", reg, this->last_error_);
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}
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return result;
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}
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} // namespace sensirion_common
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} // namespace esphome
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