| // Copyright 2020 The Pigweed Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| // use this file except in compliance with the License. You may obtain a copy of |
| // the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| // License for the specific language governing permissions and limitations under |
| // the License. |
| #pragma once |
| |
| #include <cinttypes> |
| #include <cstddef> |
| |
| #include "pw_bytes/span.h" |
| #include "pw_status/status.h" |
| |
| namespace pw::i2c { |
| |
| typedef uint16_t I2cAddress; |
| |
| // The I2cBus virtual interface for the master/controller mode that |
| // represents a single bus. This class should be inherited by the platform |
| // and provide an implementation to the methods included. |
| class I2cBus { |
| public: |
| virtual ~I2cBus() = default; |
| |
| virtual pw::Status Enable() = 0; |
| |
| virtual pw::Status Disable() = 0; |
| |
| // Write bytes in tx_buffer to the I2C bus, the read rx_buffer.size() bytes |
| // from the bus. Only write if rx_buffer is empty; only read if tx_buffer |
| // is empty |
| // |
| // Effect on the wire of this API: |
| // 1) Generate start condition |
| // If tx_buffer non-empty: |
| // 2) output the address with R/W bit 0, must be ack'd |
| // 3) the write data where each byte must be ack'd |
| // If rx_buffer non-empty: |
| // 4) output the address with R/W bit 1, must be ack'd |
| // 5) device is expected to send the entire rx buffer's worth of bytes |
| // where the master/controller must ack each and nack the last |
| // 6) Generate Stop condition |
| // TODO: A timeout or a deadline should be added to the API later |
| virtual pw::Status WriteRead(I2cAddress address, |
| ConstByteSpan tx_buffer, |
| ByteSpan rx_buffer) = 0; |
| |
| pw::Status Write(I2cAddress address, ConstByteSpan tx_buffer) { |
| ByteSpan empty_span{}; |
| return WriteRead(address, tx_buffer, empty_span); |
| } |
| |
| pw::Status Read(I2cAddress address, ByteSpan rx_buffer) { |
| ByteSpan empty_span{}; |
| return WriteRead(address, empty_span, rx_buffer); |
| } |
| }; |
| |
| } // namespace pw::i2c |