diff --git a/README.md b/README.md
index 1399e1f..7dd3b92 100644
--- a/README.md
+++ b/README.md
@@ -34,6 +34,7 @@ $ python -m rtio.test.sed.output_network
 - - [x] `rtio.cri` (`Interface` and `CRIDecoder` only)
 - - [x] `rtio.sed.output_network`
 - - [x] `rtio.sed.output_driver`
+- [ ] Simulate RTIO command for switching TTL
 
 ## License