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 DmaUartMcuxpresso in pw_uart_mcuxpresso 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 is moving to pw_uart_mcuxpresso.

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:

 1  constexpr uint32_t kFlexcomm = 0;
 2  constexpr uint32_t kBaudRate = 115200;
 3  std::array<std::byte, 20> kBuffer = {};
 4
 5  auto stream = pw::stream::UartStreamMcuxpresso{
 6      USART0, kBaudRate, kUSART_ParityDisabled, kUSART_OneStopBit, kBuffer};
 7
 8  PW_TRY(stream.Init(CLOCK_GetFlexcommClkFreq(kFlexcomm)));
 9
10  std::array<std::byte, 10> to_write = {};
11  PW_TRY(stream.Write(to_write));

InterruptSafeUartWriterMcuxpresso example:

1  constexpr uint32_t kBaudRate = 115200;
2  static constinit pw::stream::InterruptSafeUartWriterMcuxpresso
3      crash_safe_uart(USART0_BASE, kCLOCK_Flexcomm0Clk, kBaudRate);
4
5  PW_TRY(crash_safe_uart.Enable());
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