stm32/sdmmc: Fix SDIOv1 writes

1 files changed, 37 insertions, 2 deletions

diff --git a/examples/stm32f4/src/bin/sdmmc.rs b/examples/stm32f4/src/bin/sdmmc.rs
index 0edd8a61a..b57e955f6 100644
--- a/examples/stm32f4/src/bin/sdmmc.rs
+++ b/examples/stm32f4/src/bin/sdmmc.rs
@@ -4,11 +4,15 @@
 
 use defmt::*;
 use embassy_executor::Spawner;
-use embassy_stm32::sdmmc::Sdmmc;
+use embassy_stm32::sdmmc::{DataBlock, Sdmmc};
 use embassy_stm32::time::mhz;
 use embassy_stm32::{interrupt, Config};
 use {defmt_rtt as _, panic_probe as _};
 
+/// This is a safeguard to not overwrite any data on the SD card.
+/// If you don't care about SD card contents, set this to `true` to test writes.
+const ALLOW_WRITES: bool = false;
+
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) -> ! {
     let mut config = Config::default();
@@ -34,11 +38,42 @@ async fn main(_spawner: Spawner) -> ! {
     // Should print 400kHz for initialization
     info!("Configured clock: {}", sdmmc.clock().0);
 
-    unwrap!(sdmmc.init_card(mhz(25)).await);
+    unwrap!(sdmmc.init_card(mhz(24)).await);
 
     let card = unwrap!(sdmmc.card());
 
     info!("Card: {:#?}", Debug2Format(card));
+    info!("Clock: {}", sdmmc.clock());
+
+    // Arbitrary block index
+    let block_idx = 16;
+
+    // SDMMC uses `DataBlock` instead of `&[u8]` to ensure 4 byte alignment required by the hardware.
+    let mut block = DataBlock([0u8; 512]);
+
+    sdmmc.read_block(block_idx, &mut block).await.unwrap();
+    info!("Read: {=[u8]:X}...{=[u8]:X}", block[..8], block[512 - 8..]);
+
+    if !ALLOW_WRITES {
+        info!("Writing is disabled.");
+        loop {}
+    }
+
+    info!("Filling block with 0x55");
+    block.fill(0x55);
+    sdmmc.write_block(block_idx, &block).await.unwrap();
+    info!("Write done");
+
+    sdmmc.read_block(block_idx, &mut block).await.unwrap();
+    info!("Read: {=[u8]:X}...{=[u8]:X}", block[..8], block[512 - 8..]);
+
+    info!("Filling block with 0xAA");
+    block.fill(0xAA);
+    sdmmc.write_block(block_idx, &block).await.unwrap();
+    info!("Write done");
+
+    sdmmc.read_block(block_idx, &mut block).await.unwrap();
+    info!("Read: {=[u8]:X}...{=[u8]:X}", block[..8], block[512 - 8..]);
 
     loop {}
 }