pw_spi_mcuxpresso#

pw_spi_mcuxpresso implements the pw_spi interfaces using the NXP MCUXpresso SDK.

There are two initiator implementations corresponding to the SPI and FLEXIO_SPI drivers in the SDK. SPI transfer can be configured to use a blocking (by polling) method or non-blocking under the covers. The API is synchronous regardless.

There is a responder implementation McuxpressoResponder which uses the SPI and DMA drivers from the SDK.

Setup#

Use of this module requires setting up the MCUXpresso SDK for use with Pigweed. Follow the steps in pw_build_mcuxpresso to create a pw_source_set for an MCUXpresso SDK. Include the GPIO and PINT driver components in this SDK definition.

This example shows what your SDK setup would look like if using an RT595 EVK.

import("$dir_pw_third_party/mcuxpresso/mcuxpresso.gni")

pw_mcuxpresso_sdk("sample_project_sdk") {
  manifest = "$dir_pw_third_party/mcuxpresso/evkmimxrt595/EVK-MIMXRT595_manifest_v3_13.xml"
  include = [
    "component.serial_manager_uart.MIMXRT595S",
    "platform.drivers.flexio_spi.MIMXRT595S",
    "platform.drivers.flexspi.MIMXRT595S",
    "project_template.evkmimxrt595.MIMXRT595S",
    "utility.debug_console.MIMXRT595S",
  ]
}

Next, specify the pw_third_party_mcuxpresso_SDK GN global variable to specify the name of this source set. Edit your GN args with gn args out.

pw_third_party_mcuxpresso_SDK = "//targets/mimxrt595_evk:sample_project_sdk"

Then, depend on this module in your BUILD.gn to use.

deps = [ dir_pw_spi_mcuxpresso ]

Examples#

Example write using the FLEXIO_SPI initiator:

McuxpressoFlexIoInitiator spi(
   flexio_spi_config, CLOCK_GetFlexioClkFreq(), baud_rate_bps, blocking);
spi.Configure(configuration);

spi.WriteRead(source, destination);

Example use of SPI responder:

#include "pw_dma_mcuxpresso/dma.h"
#include "pw_spi_mcuxpresso/responder.h"

constinit pw::dma::McuxpressoDmaController dma(DMA0_BASE);

pw::dma::McuxpressoDmaChannel tx_dma = dma.GetChannel(kTxDmaChannel);
pw::dma::McuxpressoDmaChannel rx_dma = dma.GetChannel(kRxDmaChannel);

pw::spi::McuxpressoResponder spi_responder(
   {
      // SPI mode 3 (CPOL = 1, CPHA = 1)
      .polarity = pw::spi::ClockPolarity::kActiveLow,  // CPOL = 1
      .phase = pw::spi::ClockPhase::kFallingEdge,      // CPHA = 1
      .bits_per_word = 8,
      .bit_order = pw::spi::BitOrder::kMsbFirst,
      .base_address = SPI14_BASE,
      .handle_cs = true,
   },
   tx_dma,
   rx_dma);

pw::Status Init() {
  // Initialize the DMA controller
  PW_TRY(dma.Init());

  tx_dma.Init();
  tx_dma.SetPriority(kTxDmaChannelPriority);
  tx_dma.Enable();
  tx_dma.EnableInterrupts();

  rx_dma.Init();
  rx_dma.SetPriority(kRxDmaChannelPriority);
  rx_dma.Enable();
  tx_dma.EnableInterrupts();

  PW_TRY(spi_responder.Initialize());

  spi_responder.SetCompletionHandler([this](pw::ByteSpan rx_data, pw::Status status) {
   // Signal we got some data
  });

  // Start listen for read
  PW_TRY(spi_.WriteReadAsync(kTxData, rx_buf));
}
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