Update Readme

README.md

@@ -1,15 +1,14 @@
 # DJI Gimbal FOC
 
-The aim of this project is to be able to use the 3-axis DJI gimbal with a custom open source controller. This high quality gimbal is very tiny and easy to find as replacement part which makes it very suitable for DIY projects. 
+The aim of this project is to be able to use the 3-axis DJI gimbal with a custom open source controller like [SimpleFOC](https://docs.simplefoc.com/). This high quality gimbal is very tiny and easy to find as a replacement part which makes it very suitable for DIY projects. 
 
 ## Description
 
-todo
+![](docs/overview.jpg)
 
 ## Pinout identification
 The Gimbal is composed of a flex PCB with a main connector and 3 smaller for each motor. The main end connector is a 40-pin mezzanine board to board connectors. In order to work easily I have designed a breakout board which open to a 2.54" header. 
-
+![Setup](docs/setup.jpg)
-
 
 Here is the strategy I followed to find the pinout:
 1. Find all equipotential pins with a multimeter set to continuity tests, and test all the combinations
@@ -97,3 +96,9 @@ float dist_angle(float newAngle, float prevAngle) // return the difference modul
 
 ``` 
 
+## Tuning the PIDs
+To achive position control it is necessary to have first, a velocity controller well tuned, as they are in cascade. (SimpleFOC implementation and diagram) 
+![Closed loop position diagram from SimpleFOC](docs/angle_loop_v.png)
+
+However, the motors of the gimbal have hard stop and can only rotate of around a half turn. It was so necessary to remove these  mecanical stops. I drilled with a 1.6mm drill the two little holes to remove it. Then the motor was able to rotate freely.
+![Drilling](docs/drilling.jpg)