diff --git a/docs/manual.md b/docs/manual.md
index a9c14e8..c01c094 100644
--- a/docs/manual.md
+++ b/docs/manual.md
@@ -38,6 +38,7 @@ description: Manual
   - [Temperature Sensor](#temperature-sensor)
   - [Zero-Cross Detection](#zero-cross-detection)
   - [Compatibility with EV box like OpenEVSE](#compatibility-with-ev-box-like-openevse)
+  - [PID Tuning](#pid-tuning)
 - [Help and support](#help-and-support)
 
 ## Quick Start
@@ -581,6 +582,38 @@ You can use this value to inject in the EV box in order to prioritize EV chargin
 This is usually acceptable to give the EV box a priority over the water tank, because the water tank only need a small amount of routed energy to start heating, while the EV usually requires a threshold to start charging.
 So the router will take whatever is not used by the EV box.
 
+### PID Tuning
+
+The back config page `http://<ip>/config` has a PID tuning section which allows you to tune the PID, if you know what you are doing.
+You can change the PID calibration at runtime and teh effect will appear immediately.
+
+When `DEBUG`mdoe is activated, a WebSocket endpoint is available at `/ws/debug/pid` and will stream all the PID data in real time in a `CSV` format when automatic dimmer control is activated.
+You can quickly show then and process then in `bash` with `websocat` by typing for example:
+
+```bash
+❯  websocat ws://192.168.125.123/ws/debug/pid
+pMode,dMode,icMode,rev,setpoint,kp,ki,kd,outMin,outMax,input,output,error,pTerm,iTerm,dTerm,sum
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,630.37,0.00,-630.37,-189.11,0.00,-63.04,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,631.60,0.00,-631.60,-189.48,0.00,-0.12,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,643.14,0.00,-643.14,-192.94,0.00,-1.15,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,655.29,0.00,-655.29,-196.59,0.00,-1.21,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,641.70,0.00,-641.70,-192.51,0.00,1.36,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,626.32,0.00,-626.32,-187.90,0.00,1.54,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,632.62,0.00,-632.62,-189.79,0.00,-0.63,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,623.50,0.00,-623.50,-187.05,0.00,0.91,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,625.54,0.00,-625.54,-187.66,0.00,-0.20,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,629.77,0.00,-629.77,-188.93,0.00,-0.42,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,627.03,0.00,-627.03,-188.11,0.00,0.27,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,630.68,0.00,-630.68,-189.20,0.00,-0.36,0.00
+1,1,1,0,0.00,0.30,0.00,0.10,0.00,10000.00,628.52,0.00,-628.52,-188.55,0.00,0.22,0.00
+```
+
+You can also stream this data directly to a command-line tool that will plot in real time the graphs.
+Example of such tools:
+
+- https://github.com/keithknott26/datadash
+- https://github.com/cactusdynamics/wesplot
+
 ## Help and support
 
 - **Facebook Group**: [https://www.facebook.com/groups/yasolr](https://www.facebook.com/groups/yasolr)
@@ -588,3 +621,4 @@ So the router will take whatever is not used by the EV box.
 - **GitHub Discussions**: [https://github.com/mathieucarbou/YaSolR-OSS/discussions](https://github.com/mathieucarbou/YaSolR-OSS/discussions)
 
 - **GitHub Issues**: [https://github.com/mathieucarbou/YaSolR-OSS/issues](https://github.com/mathieucarbou/YaSolR-OSS/issues)
+```