IR Probe (dc42), Ramps 1.4, Digital Mode Issue

Hello, everyone,

I have the following problem when integrating an IR Probe (https://www.duet3d.com/IRProbe) on my Ramps 1.4 with Marlin 2.0.x:

No matter what I do, the red LED on the IR Probe lights up 4 times at each start. According to this manual (https://miscsolutions.wordpress.com/mini-height-sensor-board/) this means that the IR Probe is in analog mode. But for my application I need the digital mode. So it should light up 2 times.

As described in the manual I connected the IR Probe to the z_min endstop of the ramps board and set the corresponding settings in Marlin (pullups for z_min enabled).

#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG
//#define USE_XMAX_PLUG
//#define USE_YMAX_PLUG
//#define USE_ZMAX_PLUG

// coarse Endstop Settings
//#define ENDSTOPPULLUPS // Comment this out (using // at the start of the line) to disable the endstop pullup resistors

#if DISABLED(ENDSTOPPULLUPS)
// fine endstop settings: Individual pullups. will be ignored if ENDSTOPPULLUPS is defined
//#define ENDSTOPPULLUP_XMAX
//#define ENDSTOPPULLUP_YMAX
//#define ENDSTOPPULLUP_ZMAX
#define ENDSTOPPULLUP_XMIN
#define ENDSTOPPULLUP_YMIN
#define ENDSTOPPULLUP_ZMIN
//#define ENDSTOPPULLUP_ZMIN_PROBE
#endif

I have already measured with the voltmeter and there are about 6 V at the IR Probe. Actually it should be 5 V. Is that a problem? I also connected a voltage divider and reduced the voltage to about 4.4 V. That did not change anything.

Nevertheless, my print head remains at a large distance above the bed, before the red LED even lights up to signal the actual "triggering" of the IR Probe.

Does anyone have any experience with this and could please help me? I have already worked my way through the "Configuration.h" several times and don't know what to do.

I also saw this post: [reprap.org]
Didn't help either, unfortunately.

Many greetings
Robin

Edited 1 time(s). Last edit at 05/02/2020 01:17PM by r0bin666.

Small update:
I have checked the voltage again and there are exactly 5 V at the IR probe. According to the manual (https://miscsolutions.wordpress.com/mini-height-sensor-board/) the LED on the IR probe should blink 2 times and be in digital mode. I assume that the Arduino Mega2560 can only handle the digital signal. With the Duet boards the IR probe should receive 3.3 V in comparison. This blinks 4 times and is in analog mode. With my Delta it works exactly the same way with IR Probe + Duet 2 Wifi.

I have already turned the voltage down to 3.3 V with a step-down module out of curiosity and that didn't change anything.

I also wired the whole thing to z_max and put the pins on z_min to z_max in Marlin's pins.h, so I didn't have to change anything else in the configuration.h. So I could exclude a hardware defect of the z_min connectors.

The IR Probe has also no damage, because I already had another IR Probe on it. Once the original and once a clone. Both react exactly the same.

Now I could only try an older version of Marlin.

Greetings
Robin

Next update:
Since I went back from Marlin 2.0.x to Marlinx 1.1.x the digital mode of the IR Probe works. I haven't fully tested it yet, but the LED on the sensor now blinks twice at startup and when I use G29 to get the grid it also uses the intended height for "triggering".

Maybe this helps someone before he/she fights with Marlin 2.0.x. Whether the mistake was because of me or Marlin I can hardly say. However, I have set up both Marlin versions as far as possible the same.

Greetings
Robin