From b0287c74226f4cae02e2a58b5bb3c19ed57712d7 Mon Sep 17 00:00:00 2001
From: Ihor Kalnytskyi <ihor@kalnytskyi.com>
Date: Sun, 22 Feb 2026 02:32:52 +0200
Subject: [PATCH] Add SetDuty control command

SetDuty sets the target motor duty cycle in VESC, making it a core
control mode for direct motor actuation workflows.
---
 README.md        |  1 +
 src/command.rs   |  9 +++++++++
 tests/command.rs | 20 ++++++++++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/README.md b/README.md
index 6746dc8..4f7b3e3 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ application that needs to communicate with VESC motor controllers.
 |:----------:|-----------------------------------|--------|
 | `0`        | `FwVersion`                       | ✅     |
 | `4`        | `GetValues`                       | ✅     |
+| `5`        | `SetDuty`                         | ✅     |
 | `6`        | `SetCurrent`                      | ✅     |
 | `7`        | `SetCurrentBrake`                 | ✅     |
 | `8`        | `SetRpm`                          | ✅     |
diff --git a/src/command.rs b/src/command.rs
index a977c67..a132677 100644
--- a/src/command.rs
+++ b/src/command.rs
@@ -43,6 +43,7 @@ pub enum DecodeError {
 enum CommandId {
     FwVersion = 0,
     GetValues = 4,
+    SetDuty = 5,
     SetCurrent = 6,
     SetCurrentBrake = 7,
     SetRpm = 8,
@@ -58,6 +59,7 @@ impl TryFrom<u8> for CommandId {
         match value {
             id if id == CommandId::FwVersion as u8 => Ok(CommandId::FwVersion),
             id if id == CommandId::GetValues as u8 => Ok(CommandId::GetValues),
+            id if id == CommandId::SetDuty as u8 => Ok(CommandId::SetDuty),
             id if id == CommandId::SetCurrent as u8 => Ok(CommandId::SetCurrent),
             id if id == CommandId::SetCurrentBrake as u8 => Ok(CommandId::SetCurrentBrake),
             id if id == CommandId::SetRpm as u8 => Ok(CommandId::SetRpm),
@@ -134,6 +136,9 @@ pub enum Command<'a> {
     /// Requests the complete set of telemetry data from the VESC.
     GetValues,
 
+    /// Sets the motor duty cycle ratio. Valid range is typically -1.0 to 1.0.
+    SetDuty(f32),
+
     /// Sets the motor current in amperes. Positive values drive forward;
     /// negative values drive reverse.
     SetCurrent(f32),
@@ -172,6 +177,10 @@ impl<'a> Command<'a> {
             Self::GetValues => {
                 packer.pack_u8(CommandId::GetValues as u8)?;
             }
+            Self::SetDuty(duty) => {
+                packer.pack_u8(CommandId::SetDuty as u8)?;
+                packer.pack_f32(*duty, 100000.0)?;
+            }
             Self::SetCurrent(current) => {
                 packer.pack_u8(CommandId::SetCurrent as u8)?;
                 packer.pack_f32(*current, 1000.0)?;
diff --git a/tests/command.rs b/tests/command.rs
index c43dd7d..2c56bc6 100644
--- a/tests/command.rs
+++ b/tests/command.rs
@@ -18,6 +18,26 @@ fn encode_get_values() {
     assert_that!(buf[..size], eq([2, 1, 4, 64, 132, 3]));
 }
 
+#[test]
+fn encode_set_duty() {
+    let mut buf = [0u8; 16];
+
+    let size = vesc::encode(Command::SetDuty(0.0), &mut buf).unwrap();
+    assert_that!(buf[..size], eq([2, 5, 5, 0, 0, 0, 0, 35, 87, 3]));
+
+    let size = vesc::encode(Command::SetDuty(0.1), &mut buf).unwrap();
+    assert_that!(buf[..size], eq([2, 5, 5, 0, 0, 39, 16, 174, 23, 3]));
+
+    let size = vesc::encode(Command::SetDuty(0.57123), &mut buf).unwrap();
+    assert_that!(buf[..size], eq([2, 5, 5, 0, 0, 223, 35, 50, 79, 3]));
+
+    let size = vesc::encode(Command::SetDuty(-0.1), &mut buf).unwrap();
+    assert_that!(buf[..size], eq([2, 5, 5, 255, 255, 216, 240, 212, 6, 3]));
+
+    let size = vesc::encode(Command::SetDuty(-0.57123), &mut buf).unwrap();
+    assert_that!(buf[..size], eq([2, 5, 5, 255, 255, 32, 221, 187, 161, 3]));
+}
+
 #[test]
 fn encode_set_current() {
     let mut buf = [0u8; 16];