pw_i2c_zephyr

Zephyr implementation for pw_i2c

Experimental

pw_i2c_zephyr implements the pw_i2c interface using the Zephyr I2C drivers. Currently, only blocking calls are supported.

Support for ten-bit addresses and the no-start flag is enabled but depends on underlying support by the Zephyr driver.

Setup

Enable the module in your project’s prj.conf:

CONFIG_PIGWEED_I2C=y

For the responder API, also enable:

CONFIG_PIGWEED_I2C_RESPONDER=y

Unlike the facades documented in How backend selection works, pw_i2c_zephyr doesn’t have alternate backends to choose between, so these are plain enable flags rather than a choice. It also needs pw_sync.mutex and pw_chrono.system_clock backends – set CONFIG_PIGWEED_SYNC_MUTEX=y and CONFIG_PIGWEED_CHRONO_SYSTEM_CLOCK=y (see pw_sync_zephyr and pw_chrono_zephyr); if you forget, CMake fails the build naming the missing facade.

API reference

Moved: pw_i2c_zephyr

Initiator example

A simple example illustrating the usage of the Zephyr initiator:

constexpr struct i2c_dt_spec kDeviceSpec =
    I2C_DT_SPEC_GET(DT_NODELABEL(my_dev));
pw::i2c::ZephyrInitiator kInitiator(kDeviceSpec.bus);
pw::i2c::Device kI2cDev(kInitiator, Address::SevenBit(kDeviceSpec.addr));

Responder example

A simple example illustrating the usage of the Zephyr responder:

class MyResponderEvents : public pw::i2c::ResponderEvents {
 public:
  constexpr MyResponderEvents() : next_read_index_(0xff) {}
  bool OnWrite(ConstByteSpan data) override {
    // Save the next index to read.
    next_read_index_ = data[0];
    return true;
  }

  Result<ConstByteSpan> OnRead() override {
    // return the value
    return Result<ConstByteSpan>(
      ConstByteSpan(&buffer_[next_read_index_], 1));
  }
 private:
  uint8_t next_read_index_;
  std::byte buffer_[128];
};
constexpr struct i2c_dt_spec kDeviceSpec =
    I2C_DT_SPEC_GET(DT_NODELABEL(my_dev));
constexpr MyResponderEvents kEvents;
pw::i2c::ZephyrResponder(kDeviceSpec.bus,
    Address::SevenBit(kDeviceSpec.addr), kEvents);