Add documentation for FMC, remove outdated section from README

Author: richardeoin

README.md

@@ -110,16 +110,6 @@ The Minimum Supported Rust Version (MSRV) at the moment is **1.43.0**. Older
 versions **may** compile, especially when some features are not used
 in your application.
 
-Other STM32H7 crates
---------------------
-
-This crate only includes implmentations of [embedded-hal][] traits or
-other core functionality. An incomplete list of additional peripheral
-support crates is given here:
-
-- [stm32h7-fmc](https://crates.io/crates/stm32h7-fmc)
-- _[Search crates.io...](https://crates.io/search?q=stm32h7)_
-
 Changelog
 ---------
 

examples/fmc.rs

@@ -151,7 +151,7 @@ const APP: () = {
         // ----------------------------------------------------------
         // SDRAM
         // Initialise SDRAM...
-        let fmc_io = fmc_pins! {
+        let sdram_pins = fmc_pins! {
             // A0-A11
             gpiof.pf0, gpiof.pf1, gpiof.pf2, gpiof.pf3,
             gpiof.pf4, gpiof.pf5, gpiof.pf12, gpiof.pf13,
@@ -178,7 +178,7 @@ const APP: () = {
         };
 
         let mut sdram = dp.FMC.sdram(
-            fmc_io,
+            sdram_pins,
             is42s32800g_6::Is42s32800g {},
             ccdr.peripheral.FMC,
             &ccdr.clocks,

src/fmc.rs

@@ -1,4 +1,30 @@
 //! HAL for Flexible memory controller (FMC)
+//!
+//! FMC support is implemented via the
+//! [stm32-fmc](https://github.com/stm32-rs/stm32-fmc) crate.
+//!
+//! ## SDRAM
+//!
+//! An external SDRAM can be instantiated by calling the [sdram](FmcExt::sdram)
+//! extension method. To avoid the pin checks, you can use
+//! [sdram_unchecked](FmcExt::sdram_unchecked) instead.
+//!
+//! ```
+//! use stm32h7xx_hal::prelude::*;
+//!
+//! let sdram_pins = ...; // Tuple, see stm32-fmc docs for pin ordering
+//! let sdram_chip = ...; // See stm32-fmc docs
+//!
+//! let mut sdram = dp.FMC.sdram(
+//!     sdram_pins,
+//!     sdram_chip,
+//!     ccdr.peripheral.FMC,
+//!     &ccdr.clocks,
+//! );
+//! ```
+//!
+//! `sdram` usage is described
+//! [here](https://github.com/stm32-rs/stm32-fmc#usage).
 
 // From stm32_fmc
 use stm32_fmc::FmcPeripheral;