| .. _module-pw_stream_uart_mcuxpresso: |
| |
| ========================= |
| pw_stream_uart_mcuxpresso |
| ========================= |
| ``pw_stream_uart_mcuxpresso`` implements the ``pw_stream`` interface for reading |
| and writing to a UART using the NXP MCUXpresso SDK. ``UartStreamMcuxpresso`` |
| version uses the CPU to read and write to the UART, while ``UartDmaStreamMcuxpresso`` |
| uses DMA transfers to read and write to the UART minimizing the CPU utilization. |
| |
| ``InterruptSafeUartWriterMcuxpresso`` implements an interrupt safe |
| write-only stream to UART. Intended for use in fault handlers. It can be |
| constructed ``constinit`` for use in pre-static constructor environments as well. |
| |
| .. note:: |
| This module will likely be superseded by a future ``pw_uart`` interface. |
| |
| Setup |
| ===== |
| This module requires a little setup: |
| |
| 1. Use ``pw_build_mcuxpresso`` to create a ``pw_source_set`` for an |
| MCUXpresso SDK. |
| 2. Include the debug console component in this SDK definition. |
| 3. Specify the ``pw_third_party_mcuxpresso_SDK`` GN global variable to specify |
| the name of this source set. |
| 4. Use a target that calls ``pw_sys_io_mcuxpresso_Init`` in |
| ``pw_boot_PreMainInit`` or similar. |
| |
| The name of the SDK source set must be set in the |
| "pw_third_party_mcuxpresso_SDK" GN arg |
| |
| Usage |
| ===== |
| |
| ``UartStreamMcuxpresso`` example: |
| |
| .. code-block:: cpp |
| |
| constexpr uint32_t kFlexcomm = 0; |
| constexpr uint32_t kBaudRate = 115200; |
| std::array<std::byte, 20> kBuffer = {}; |
| |
| auto stream = UartStreamMcuxpresso{USART0, |
| kBaudRate, |
| kUSART_ParityDisabled, |
| kUSART_OneStopBit, |
| kBuffer}; |
| |
| PW_TRY(stream.Init(CLOCK_GetFlexcommClkFreq(kFlexcomm))); |
| |
| std::array<std::byte, 10> to_write = {}; |
| PW_TRY(stream.Write(to_write)); |
| |
| |
| ``UartDmaStreamMcuxpresso`` example: |
| |
| .. code-block:: cpp |
| |
| constexpr uint32_t kFlexcomm = 0; |
| const auto kUartBase = USART0; |
| constexpr uint32_t kBaudRate = 115200; |
| std::array<std::byte, 65536> ring_buffer = {}; |
| constexpr uint32_t kUartRxDmaCh = 0; |
| constexpr uint32_t kUartTxDmaCh = 1; |
| |
| const UartDmaStreamMcuxpresso::Config kConfig = { |
| .usart_base = kUartBase, |
| .baud_rate = kBaudRate, |
| .parity = kUSART_ParityDisabled, |
| .stop_bits = kUSART_OneStopBit, |
| .dma_base = DMA0, |
| .rx_dma_ch = kUartRxDmaCh, |
| .tx_dma_ch = kUartTxDmaCh, |
| .rx_input_mux_dmac_ch_request_en = kINPUTMUX_Flexcomm0RxToDmac0Ch0RequestEna, |
| .tx_input_mux_dmac_ch_request_en = kINPUTMUX_Flexcomm0TxToDmac0Ch1RequestEna, |
| .buffer = ByteSpan(ring_buffer)}; |
| |
| auto stream = UartDmaStreamMcuxpresso{kConfig}; |
| |
| PW_TRY(stream.Init(CLOCK_GetFlexcommClkFreq(kFlexcomm))); |
| |
| ``InterruptSafeUartWriterMcuxpresso`` example: |
| |
| .. code-block:: cpp |
| |
| constinit InterruptSafeUartWriterMcuxpresso crash_safe_uart( |
| USART0_BASE, kCLOCK_Flexcomm0Clk, 115200); |
| |
| PW_TRY(crash_safe_uart.Enable()); |