Update battery documentation

docs/battery_boards/bat_board/bat_protocol.md

@@ -65,16 +65,38 @@ where:
 
 - DCDC_status_B:
 
-    Position | BIT[1] | BIT[0] |
-    |:---|:---:|:---:|
-    Value | PB1_restart | PB2_restart |
-    Description | Restart phase of the push button 1 | Restart phase of the push button 2 |
-    Possible status | Start-up phase(1)/stable operation(0) | Start-up phase/stable operation |
+    Position | BIT[3] | BIT[2] | BIT[1] | BIT[0] |
+    |:---|:---:|:---:|:---:|:---:|
+    Value | HSM_SW_F | HSM_HW_F | PB1_restart | PB2_restart |
+    Description | OC Fault on the HSM triggered by overcurrent (threshold defined in the FW) | OC Fault on the HSM triggered by FLT Pin on the HSM micro | Restart phase of the push button 1 | Restart phase of the push button 2 |
+    Possible status | FAULT_OFF(0)/FAULT_ON(1) | FAULT_OFF(0)/FAULT_ON(1) | Start-up phase(1)/stable operation(0) | Start-up phase/stable operation |
 
 - Final status shown at the port is equal to: 
 
     `(DCDC_status_B << 8 ) | DCDC_status_A`
 
+Thereby, the end user sees a decimal number on the BAT Display, which can be transformed in BITs and analyzed as described below:
+
+```console
+
+**BIT_POS**:  15    14   13   12    11         10      9    8      7          6          5         4         3     2      1        0
+
+**VALUE**:    NAN  NAN  NAN  NAN  HSM_SW_F  HSM_HW_F  PB1  PB2  V12board  V12board_F  V12motor  V12motor_F  HSM  HSM_PG  HSM_F  HSM_broken
+
+E.g.
+
+If we get 172 as decimal value, then we will have in bits: 
+
+    0000 0000 1010 1100  
+
+meaning that we have on the bits related to:
+
+- HSM_PG
+- HSM
+- V12motor
+- V12board
+
+```
 
 ### Data displayed on the yarp port
 

docs/robot_power/robot_power_button.md

@@ -21,3 +21,17 @@ On iCub3 and on R1 there is also a display that shows the voltage and current pr
 |:---:|:---:|
 | <img src="../assets/fig-icub3-4.png" height="200"> | <img src="../assets/fig-r1-1.png" height="200"> |
 
+
+## Display Interface
+
+Lately, we released a new version of the Display UX/UI.
+The main screen is described in the image below for both iCub3, ergoCub, and R1:
+
+<img src="../assets/display-screen-131.png" width="500" height="500">
+
+
+If a fault occurs, the Display will switch to a different mode displaying a string that includes the error type and the last values of voltage and currents acquired at the moment of the fault.
+
+An example is shown below. On the left, the errors are related to CPU line, whereas on the right, we have errors related to BOARDS/MOTORS line.
+
+<img src="../assets/display-fault-screen-131.png" width="500" height="500">