From 1cac50dd5d1f9cb7dccee44a7086295e669cd5aa Mon Sep 17 00:00:00 2001
From: Florian Jung <flo@windfis.ch>
Date: Tue, 13 Apr 2021 01:03:24 +0200
Subject: [PATCH] Update README

---
 README.md | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index df9a38b..c6bdc79 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,7 @@ fn main() -> ! {
 
     let usb_bus = UsbBus::new(usb);
 
-    let mut midi = MidiClass::new(&usb_bus);
+    let mut midi = MidiClass::new(&usb_bus, 1, 1);
 
     let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x16c0, 0x5e4))
         .product("MIDI Test")
@@ -68,4 +68,20 @@ fn main() -> ! {
         }
     }
 }
-```
\ No newline at end of file
+```
+
+## Using more than one MIDI port
+
+Calling `MidiClass::new(&usb_bus, N, M);` with `N, M >= 1` to provide more
+than one input or output port requires the `control-buffer-256` feature of
+the usb-device crate:
+
+Cargo.toml:
+```
+usb-device = { version = ">=0.2.1", features = ["control-buffer-256"] }
+```
+
+Up to 5 in/out pairs can be used this way until we again run out of buffer
+space. Note that exceeding the available buffer space will silently fail
+to send the descriptors correctly, no obvious `panic!` will hint the
+actual problem.