From 74d6b2b1d6533b56ac86692e37d91217a8ba810a Mon Sep 17 00:00:00 2001
From: Laurens Valk <laurens@pybricks.com>
Date: Mon, 13 Nov 2023 10:28:22 +0100
Subject: [PATCH] pbio/drivebase: Reverse turn rate for negative drive speed.

See https://github.com/pybricks/support/issues/1191
---
 CHANGELOG.md             | 6 ++++++
 lib/pbio/src/drivebase.c | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ca869a4ef..30d67dd50 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,12 @@
 - Added `MoveHub.imu.tilt()` ([support#539]).
 - Enabled hub init orientation support for Move Hub ([support#539]).
 
+### Changed
+- Changed steering direction with `DriveBase.drive()` when reversing. Now, 
+  a positive angle or turn rate means the robot travels along a circle to
+  its right. The speed or radius can be negated to travel in reverse along
+  that same circle ([support#1191]).
+
 ### Fixed
 - Fixed Move Hub accelerometer not working since v3.3.0b5 ([support#1269]).
 - Fixed Bluetooth chip locking up on Technic and City hubs when broadcasting ([support#1095]).
diff --git a/lib/pbio/src/drivebase.c b/lib/pbio/src/drivebase.c
index ae1d94a17..15e931200 100644
--- a/lib/pbio/src/drivebase.c
+++ b/lib/pbio/src/drivebase.c
@@ -641,6 +641,12 @@ static pbio_error_t pbio_drivebase_drive_time_common(pbio_drivebase_t *db, int32
         return err;
     }
 
+    // When reversing, also reverse steering. This way, driving backwards without
+    // changing the steering sign means driving along the same circle, backwards.
+    if (drive_speed < 0) {
+        turn_speed = -turn_speed;
+    }
+
     err = pbio_control_start_timed_control(&db->control_heading, time_now, &state_heading, duration, turn_speed, on_completion);
     if (err != PBIO_SUCCESS) {
         return err;