Rumba and Auto-Bed level

[ex-egll]

Hi, I have recently tried to get the ABL working on my i3v 12", unfortunately without too much success. In fact the only success so far is the fact that no smoke has been released from the RUMBA board.

After much wading through forums and you tube I put together a "plan of action":

1. The standard servo plug needs rewiring to plug into the RUMBA board
Reverse the +ve and -ve wires so that the -ve is in the middle pin and +ve and signal are on the outer pins

2. Connect the servo to the RUMBA board as follows
+ve pin 2 of EXP3 +5v
-ve pin 4 of EXP3 GND
sig pin 6 of EXP3 PWM1

3. Relocate the Z end switch to the servo arm.

4. Edit pins.h file
Change Line 455 from
#define SERVO0_PIN 11
to
#define SERVO0_PIN 5
this assigns the servo signal line to PWM2 which is Pin5 on the 2560 CPU chip and Pin 6 on EXP3

5. Edit Configuration.h file
Change line 291 from
#define min_software_endstops true
to
#define min_software_endstops false
allows nozzle to go below 0 as set by probe

Uncomment line 296
//#define ENABLE_AUTO_BED_LEVELING

Change line 311 from
#define XY_TRAVEL_SPEED 8000 // X and Y axis travel speed between probes, in mm/min
to
#define XY_TRAVEL_SPEED 4000 // X and Y axis travel speed between probes, in mm/min
Reduces probe speed to a more conservative value.

Uncomment and change Line 576 from
//#define NUM_SERVOS 3 // Servo index starts with 0 for M280 command
to
#define NUM_SERVOS 1 // Servo index starts with 0 for M280 command

Uncomment lines 583 and 584
//#define SERVO_ENDSTOPS {-1, -1, 0} // Servo index for X, Y, Z. Disable with -1
//#define SERVO_ENDSTOP_ANGLES {0,0, 0,0, 70,0} // X,Y,Z Axis Extend and Retract angles

References:
http://zennmaster.com/random-things
http://3dprintboard.com/showthread.p...ed-level/page3

The above changes compiled and uploaded OK

After connecting the servo to the board I issued a M280 P0 110 command from OctoPi, the terminal window showed the following:

Send: M280 P0 110
Recv: ok Servo 0: 110

but, the arm did not move.

I then repeated the above with a different value M280 P0 20 the terminal window showed the following:

Send: M280 P0 20
Recv: ok Servo 0: 110

The value in the Recv field displayed the originally sent value. A reboot of the RUMBA was needed to get the system to return the correct value, but again this was only returned on the first string sent.

The servo has been tested, and works on an Arduino UNO. Have I missed anything out in the prep work?

UPDATE:
I think that I should have sent M280 P0 S110 not M280 P0 110, but it made no difference. Likewise M401 M402 did not work.