Circuitry sample for PS/2 Mouse (#3959)

Added a sample circuitry for handling the connection of a PS/2 Mouse.
    Even if it's written that a circuitry is needed, there're a lot of other
    things and the information gets lost really fast. A really simple sample
    helps to remember who wants to implement the functionality about the
    circuitry.

1 files changed, 18 insertions, 0 deletions

diff --git a/docs/feature_ps2_mouse.md b/docs/feature_ps2_mouse.md
index 909406e7d..01e2cc63d 100644
--- a/docs/feature_ps2_mouse.md
+++ b/docs/feature_ps2_mouse.md
@@ -6,6 +6,24 @@ To hook up a Trackpoint, you need to obtain a Trackpoint module (i.e. harvest fr
 
 There are three available modes for hooking up PS/2 devices: USART (best), interrupts (better) or busywait (not recommended).
 
+### The Cirtuitry between Trackpoint and Controller
+
+To get the things working, a 4.7K drag is needed between the two lines DATA and CLK and the line 5+. 
+
+```
+
+          DATA ----------+--------- PIN
+                         |
+                        4.7K
+                         |
+MODULE    5+  --------+--+--------- PWR   CONTROLLER
+                      |
+                     4.7K
+                      |    
+          CLK   ------+------------ PIN
+```
+
+
 ### Busywait Version
 
 Note: This is not recommended, you may encounter jerky movement or unsent inputs. Please use interrupt or USART version if possible.