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|
//! DMA Scatter-Gather Builder example for MCXA276.
//!
//! This example demonstrates using the new `ScatterGatherBuilder` API for
//! chaining multiple DMA transfers with a type-safe builder pattern.
//!
//! # Features demonstrated:
//! - `ScatterGatherBuilder::new()` for creating a builder
//! - `add_transfer()` for adding memory-to-memory segments
//! - `build()` to start the chained transfer
//! - Automatic TCD linking and ESG bit management
//!
//! # Comparison with manual scatter-gather:
//! The manual approach (see `dma_scatter_gather.rs`) requires:
//! - Manual TCD pool allocation and alignment
//! - Manual CSR/ESG/INTMAJOR bit manipulation
//! - Manual dlast_sga address calculations
//!
//! The builder approach handles all of this automatically!
#![no_std]
#![no_main]
use embassy_executor::Spawner;
use embassy_mcxa::clocks::config::Div8;
use embassy_mcxa::dma::{DmaChannel, ScatterGatherBuilder};
use static_cell::ConstStaticCell;
use {defmt_rtt as _, embassy_mcxa as hal, panic_probe as _};
// Source buffers (multiple segments)
static SRC1: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0x11111111, 0x22222222, 0x33333333, 0x44444444]);
static SRC2: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0xAAAAAAAA, 0xBBBBBBBB, 0xCCCCCCCC, 0xDDDDDDDD]);
static SRC3: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0x12345678, 0x9ABCDEF0, 0xFEDCBA98, 0x76543210]);
// Destination buffers (one per segment)
static DST1: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0; 4]);
static DST2: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0; 4]);
static DST3: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0; 4]);
#[embassy_executor::main]
async fn main(_spawner: Spawner) {
// Small delay to allow probe-rs to attach after reset
for _ in 0..100_000 {
cortex_m::asm::nop();
}
let mut cfg = hal::config::Config::default();
cfg.clock_cfg.sirc.fro_12m_enabled = true;
cfg.clock_cfg.sirc.fro_lf_div = Some(Div8::no_div());
let p = hal::init(cfg);
defmt::info!("DMA Scatter-Gather Builder example starting...");
defmt::info!("DMA Scatter-Gather Builder Example");
defmt::info!("===================================");
let src1 = SRC1.take();
let src2 = SRC2.take();
let src3 = SRC3.take();
let dst1 = DST1.take();
let dst2 = DST2.take();
let dst3 = DST3.take();
// Show source buffers
defmt::info!("Source buffers:");
defmt::info!(" SRC1: {=[?]}", src1.as_slice());
defmt::info!(" SRC2: {=[?]}", src2.as_slice());
defmt::info!(" SRC3: {=[?]}", src3.as_slice());
defmt::info!("Destination buffers (before):");
defmt::info!(" DST1: {=[?]}", dst1.as_slice());
defmt::info!(" DST2: {=[?]}", dst2.as_slice());
defmt::info!(" DST3: {=[?]}", dst3.as_slice());
// Create DMA channel
let dma_ch0 = DmaChannel::new(p.DMA_CH0);
defmt::info!("Building scatter-gather chain with builder API...");
// =========================================================================
// ScatterGatherBuilder API demonstration
// =========================================================================
//
// The builder pattern makes scatter-gather transfers much easier:
// 1. Create a builder
// 2. Add transfer segments with add_transfer()
// 3. Call build() to start the entire chain
// No manual TCD manipulation required!
let mut builder = ScatterGatherBuilder::<u32>::new();
// Add three transfer segments - the builder handles TCD linking automatically
builder.add_transfer(src1, dst1);
builder.add_transfer(src2, dst2);
builder.add_transfer(src3, dst3);
defmt::info!("Added 3 transfer segments to chain.");
defmt::info!("Starting scatter-gather transfer with .await...");
// Build and execute the scatter-gather chain
// The build() method:
// - Links all TCDs together with ESG bit
// - Sets INTMAJOR on all TCDs
// - Loads the first TCD into hardware
// - Returns a Transfer future
let transfer = builder.build(&dma_ch0).expect("Failed to build scatter-gather");
transfer.blocking_wait();
defmt::info!("Scatter-gather transfer complete!");
// Show results
defmt::info!("Destination buffers (after):");
defmt::info!(" DST1: {=[?]}", dst1.as_slice());
defmt::info!(" DST2: {=[?]}", dst2.as_slice());
defmt::info!(" DST3: {=[?]}", dst3.as_slice());
let comps = [(src1, dst1), (src2, dst2), (src3, dst3)];
// Verify all three segments
let mut all_ok = true;
for (src, dst) in comps {
all_ok &= src == dst;
}
if all_ok {
defmt::info!("PASS: All segments verified!");
} else {
defmt::error!("FAIL: Mismatch detected!");
}
defmt::info!("=== Scatter-Gather Builder example complete ===");
}
|
