LEGO EV3 Infrared Sensor (45509)

General

This sensor uses the msensor device class.

	Value
type_id	33
# Modes	6
Connection	UART

Mode 0

	Mode 0	Mode 1	Mode 2	Mode 3	Mode 44	Mode 55
mode	IR-PROX	IR-SEEK	IR-REMOTE	IR-REM-A	IR-S-ALT	IR-CAL
Description	Proximity	IR Seeker1	IR Remote Control2	Alternate IR Remote Control	Alternate IR Seeker	Calibration???
num_values	1	8	4	1	4	2
value0	Proximity (distance)	Channel 1 Heading	Channel 1	Channel 13	???
Min	0 (very close)	-25 (far left)	0 (none)		0 (???)	0 (???)
Max	100 (far away - approx. 70cm/27in)	25 (far right)	11 (blue up and blue down)		100 (???)	1023 (???)
value1		Channel 1 Proximity	Channel 2		???
Min		0 (close)	0 (none)		0 (???)	0 (???)
Max		100 (far away - approx. 200cm/79in)	11 (blue up and blue down)		100 (???)	1023 (???)
value2		Channel 2 Heading	Channel 3		???
Min		-25	0 (none)		0 (???)
Max		25	11 (blue up and blue down)		100 (???)
value3		Channel 2 Proximity	Channel 4		???
Min		0	0 (none)		0 (???)
Max		100	11 (blue up and blue down)		100 (???)
value4		Channel 3 Heading
Min		-25
Max		25
value5		Channel 3 Proximity
Min		0
Max		100
value6		Channel 4 Heading
Min		-25
Max		25
value7		Channel 4 Proximity
Min		0
Max		100
units	pct (percentage)	pct (percentage)	btn (button2)	none3	pct (percentage)	none
dp (decimal places)	0	0	0	0	0	0

Values in the tables that look like ```this``` are the names of sysfs attributes or values returned by said attributes.

[1]: The absence of a beacon on a channel can be detected when Proximity == -128 (and heading == 0).

[2]: Pressing more that 2 buttons at one time is not supported. It will usually read 0. Pressing an up/down button while beacon mode is activated with turn off beacon mode.

Button values:

Value	Description
0	none
1	red up
2	red down
3	blue up
4	blue down
5	red up and blue up
6	red up and blue down
7	red down and blue up
8	red down and blue down
9	beacon mode on
10	red up and red down
11	blue up and blue down

[3]: The most significant byte is always 0x01. In the least significant byte, the 4 most significant bits represent each button. Bit 7 is the blue down button, bit 6 is the blue up button, bit 5 is the red down button, bit 4 is the red up button. Beware that when no buttons are pressed, bit 7 is set (value == 384). You can test that bits 0-3 are all 0 to check this.

if ((value & 0x0F) == 0) {
    // no buttons are pressed
} else {
    if (value & 0x80)
        // blue down button is pressed
    if (value & 0x40)
        // blue up button is pressed
    if (value & 0x20)
        // red down button is pressed
    if (value & 0x10)
        // red up button is pressed
}

Bits 0-3 seem to be some sort of checksum or parity check. Bit 0 = bit 4, bit 1 = ~(bit 5), bit 2 = ~(bit 6), bit 3 = 0 if bits 0-2 are even or 1 if bits 0-2 are odd.

Also, when the beacon mode is active or for about 1 second after any button is released the value is 262. This mode only works with the remote on channel 1.

Values:

Value	Blue Down	Blue Up	Red Down	Red Up
262/384
287				X
300			X
309			X	X
330		X
339		X		X
352		X	X
377		X	X	X
390	X
415	X			X
428	X		X
437	X		X	X
458	X	X
467	X	X		X
480	X	X	X
505	X	X	X	X
X = Button pressed

[4] IR-S-ALT mode does not seem to be usable. When switching to this mode, the sensor quits responding to the keep-alive messages and the sensor resets.

[5] Not sure how this IR-CAL mode is supposed to work. Probably have to write some data to the sensor. Values return 0.