Merge pull request #3057 from dvdsk/docs-net-size

Document w5500 State and add w5500 example for stmf4

1 files changed, 10 insertions, 0 deletions

diff --git a/embassy-net-wiznet/src/lib.rs b/embassy-net-wiznet/src/lib.rs
index da70d22bd..90102196a 100644
--- a/embassy-net-wiznet/src/lib.rs
+++ b/embassy-net-wiznet/src/lib.rs
@@ -17,12 +17,22 @@ use embedded_hal_async::spi::SpiDevice;
 use crate::chip::Chip;
 use crate::device::WiznetDevice;
 
+// If you change this update the docs of State
 const MTU: usize = 1514;
 
 /// Type alias for the embassy-net driver.
 pub type Device<'d> = embassy_net_driver_channel::Device<'d, MTU>;
 
 /// Internal state for the embassy-net integration.
+///
+/// The two generic arguments `N_RX` and `N_TX` set the size of the receive and
+/// send packet queue. With a the ethernet MTU of _1514_ this takes up `N_RX +
+/// NTX * 1514` bytes. While setting these both to 1 is the minimum this might
+/// hurt performance as a packet can not be received while processing another.
+///
+/// # Warning
+/// On devices with a small amount of ram (think ~64k) watch out with the size
+/// of there parameters. They will quickly use too much RAM.
 pub struct State<const N_RX: usize, const N_TX: usize> {
     ch_state: ch::State<MTU, N_RX, N_TX>,
 }