LinuxCNC HAL Pin Names: Belkin Nostromo N52 SpeedPad

A (formerly Belkin, now Razer, which is evidently unrelated to Mazer Rackham) Nostromo N52 SpeedPad might not be a perfect CNC pendant, but it does have plenty of buttons and an (oddly oriented) XY joypad that might be useful for, say, a 3D printer controller running LinuxCNC.

Following the same path as with the Logitech Dual Action Gamepad that became the Joggy Thing, we find that the N52 reports itself as a keyboard and a mouse:

less /proc/bus/input/devices

... snippage ...
I: Bus=0003 Vendor=050d Product=0815 Version=0110
N: Name="Honey Bee  Nostromo SpeedPad2 "
P: Phys=usb-0000:00:02.0-10/input0
S: Sysfs=/devices/pci0000:00/0000:00:02.0/usb2/2-10/2-10:1.0/input/input3
U: Uniq=
H: Handlers=kbd event3
B: EV=100013
B: KEY=e080ffdf 1cfffff ffffffff fffffffe
B: MSC=10

I: Bus=0003 Vendor=050d Product=0815 Version=0110
N: Name="Honey Bee  Nostromo SpeedPad2 "
P: Phys=usb-0000:00:02.0-10/input1
S: Sysfs=/devices/pci0000:00/0000:00:02.0/usb2/2-10/2-10:1.1/input/input4
U: Uniq=
H: Handlers=mouse1 event4
B: EV=20017
B: KEY=70000 0 0 0 0 0 0 0 0
B: REL=103
B: MSC=10
B: LED=7

The corresponding device files belong to the root user:

ll /dev/input
... snippage ...
crw-r-----  1 root root 13, 67 2013-02-08 11:06 event3
crw-r-----  1 root root 13, 68 2013-02-08 11:06 event4
... snippage ...
crw-r-----  1 root root 13, 33 2013-02-08 11:06 mouse1

Which calls for some udev trickery to change the owner & permissions during boot / hotplugging so that it becomes available to mere mortals such as I.

First, get the bus connection information:

lsusb
... snippage ...
Bus 002 Device 004: ID 050d:0815 Belkin Components Nostromo n52 HID SpeedPad Mouse Wheel
... snippage ...

Then dump the attributes:

udevadm info --query=all --attribute-walk --name=/dev/bus/usb/002/004

Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/pci0000:00/0000:00:02.0/usb2/2-10':
    KERNEL=="2-10"
    SUBSYSTEM=="usb"
    DRIVER=="usb"
    ATTR{configuration}==""
    ATTR{bNumInterfaces}==" 2"
    ATTR{bConfigurationValue}=="1"
    ATTR{bmAttributes}=="80"
    ATTR{bMaxPower}==" 90mA"
    ATTR{urbnum}=="1354"
    ATTR{idVendor}=="050d"
    ATTR{idProduct}=="0815"
    ATTR{bcdDevice}=="0210"
    ATTR{bDeviceClass}=="00"
    ATTR{bDeviceSubClass}=="00"
    ATTR{bDeviceProtocol}=="00"
    ATTR{bNumConfigurations}=="1"
    ATTR{bMaxPacketSize0}=="8"
    ATTR{speed}=="1.5"
    ATTR{busnum}=="2"
    ATTR{devnum}=="4"
    ATTR{version}==" 1.10"
    ATTR{maxchild}=="0"
    ATTR{quirks}=="0x0"
    ATTR{authorized}=="1"
    ATTR{manufacturer}=="Honey Bee "
    ATTR{product}=="Nostromo SpeedPad2 "

... snippage ...

Note the trailing blank in the manufacturer and product values.

Create a new rules file /etc/udev/rule/90-Nostromo.rules to change the group and permissions:

# Belkin Nostromo N52 SpeedPad controller for LinuxCNC
# Ed Nisley - KE4ZNU - February 2013

ATTRS{product}=="Nostromo SpeedPad2",GROUP="plugdev",MODE="0660"

Note that the file name must start with a number around 90- to avoid being clobbered by a rule in /lib/udev/rules.d/50-udev-default.rules that (re)sets the permissions to 0640; the doc suggests that rules without numbers happen after all the number rules, so perhaps you could just use meaningful names. That took an embarrassingly long time to figure out…

There’s no need for the trailing blank in that rule, as the match proceeds left-to-right and stops at the end of the test string.

You must, perforce, be in the plugdev group. If not, add yourself.

You need not unplug the N52 to test the rule. Just use:

sudo udevadm trigger

Which produces the desired result:

crw-rw----  1 root plugdev 13, 67 2013-02-08 15:09 event3
crw-rw----  1 root plugdev 13, 68 2013-02-08 15:09 event4
... snippage ...
crw-rw----  1 root plugdev 13, 33 2013-02-08 15:09 mouse1

Poking around using, among other things, xev reveals:

• Main keypad is the left half of a standard QWERTY keyboard
• Joypad returns cursor keys, center push = nothing
• Orange button is, weirdly, the Left-Alt key
• Wheel is a mouse scroll wheel
• Push wheel = middle mouse button
• Thumb pad = space
• RGB LEDs are, respectively, num-, caps-, and scroll-lock

Then load HAL:

halrun
loadusr -W hal_input -K +Nostromo:0 -KRL +Nostromo:1
show pin input.*
loadusr halmeter

The + prefix tells HAL to capture the named device and prevent its events from reaching X. The KRL codes suggest which functions you’re interested in for that particular device. The suffix digit selects successive devices for multiple gadgets matching the same name string.

Apparently, the N52 reports it can produce all the usual keyboard and mouse values & buttons, even if they’re not connected to physical hardware. I suspect it has generic keyboard / mouse controllers inside, with just a few of the usual matrix crosspoints connected to switches.

The basic key mapping, sorted by the Nostromo functions:

Type	Dir	Name	Nostromo key
bit	OUT	input.0.key-tab	F1
bit	OUT	input.0.key-q	F2
bit	OUT	input.0.key-w	F3
bit	OUT	input.0.key-e	F4
bit	OUT	input.0.key-r	F5
bit	OUT	input.0.key-capslock	F6
bit	OUT	input.0.key-a	F7
bit	OUT	input.0.key-s	F8
bit	OUT	input.0.key-d	F9
bit	OUT	input.0.key-f	F10
bit	OUT	input.0.key-leftshift	F11
bit	OUT	input.0.key-z	F12
bit	OUT	input.0.key-x	F13
bit	OUT	input.0.key-c	F14
bit	OUT	input.0.key-space	F15
bit	OUT	input.0.key-leftalt	Orange button
bit	OUT	input.0.key-right	Pad bottom
bit	OUT	input.0.key-down	Pad front
bit	OUT	input.0.key-up	Pad rear
bit	OUT	input.0.key-left	Pad top
bit	OUT	input.1.btn-middle	Wheel press
s32	OUT	input.1.rel-wheel-counts	Scroll wheel
bit	IN	input.1.led-numl	Red LED
bit	IN	input.1.led-capsl	Green LED
bit	IN	input.1.led-scrolll	Blue LED

The bit pins also have inverted values available on the corresponding -not pins. The LEDs have an -invert that flips the sense of the input pin. The rel-wheel pin has other useful tidbits as suffixes; the count changes by ±1 for each wheel detent.

The Tab key and all the letters auto-repeat, the various Shift and Alt keys do not. That seems to make no difference to the bit values reported by HAL.

The complete table, sorted by HAL pin name:

Type	Dir	Name	Nostromo key
bit	OUT	input.0.key-0
bit	OUT	input.0.key-0-not
bit	OUT	input.0.key-1
bit	OUT	input.0.key-1-not
bit	OUT	input.0.key-102nd
bit	OUT	input.0.key-102nd-not
bit	OUT	input.0.key-2
bit	OUT	input.0.key-2-not
bit	OUT	input.0.key-3
bit	OUT	input.0.key-3-not
bit	OUT	input.0.key-4
bit	OUT	input.0.key-4-not
bit	OUT	input.0.key-5
bit	OUT	input.0.key-5-not
bit	OUT	input.0.key-6
bit	OUT	input.0.key-6-not
bit	OUT	input.0.key-7
bit	OUT	input.0.key-7-not
bit	OUT	input.0.key-8
bit	OUT	input.0.key-8-not
bit	OUT	input.0.key-9
bit	OUT	input.0.key-9-not
bit	OUT	input.0.key-a	F7
bit	OUT	input.0.key-a-not
bit	OUT	input.0.key-apostrophe
bit	OUT	input.0.key-apostrophe-not
bit	OUT	input.0.key-b
bit	OUT	input.0.key-b-not
bit	OUT	input.0.key-backslash
bit	OUT	input.0.key-backslash-not
bit	OUT	input.0.key-backspace
bit	OUT	input.0.key-backspace-not
bit	OUT	input.0.key-c	F14
bit	OUT	input.0.key-c-not
bit	OUT	input.0.key-capslock	F6
bit	OUT	input.0.key-capslock-not
bit	OUT	input.0.key-comma
bit	OUT	input.0.key-comma-not
bit	OUT	input.0.key-compose
bit	OUT	input.0.key-compose-not
bit	OUT	input.0.key-d	F9
bit	OUT	input.0.key-d-not
bit	OUT	input.0.key-delete
bit	OUT	input.0.key-delete-not
bit	OUT	input.0.key-dot
bit	OUT	input.0.key-dot-not
bit	OUT	input.0.key-down	Pad left
bit	OUT	input.0.key-down-not
bit	OUT	input.0.key-e	F4
bit	OUT	input.0.key-e-not
bit	OUT	input.0.key-end
bit	OUT	input.0.key-end-not
bit	OUT	input.0.key-enter
bit	OUT	input.0.key-enter-not
bit	OUT	input.0.key-equal
bit	OUT	input.0.key-equal-not
bit	OUT	input.0.key-esc
bit	OUT	input.0.key-esc-not
bit	OUT	input.0.key-f	F10
bit	OUT	input.0.key-f-not
bit	OUT	input.0.key-f1
bit	OUT	input.0.key-f1-not
bit	OUT	input.0.key-f10
bit	OUT	input.0.key-f10-not
bit	OUT	input.0.key-f11
bit	OUT	input.0.key-f11-not
bit	OUT	input.0.key-f12
bit	OUT	input.0.key-f12-not
bit	OUT	input.0.key-f2
bit	OUT	input.0.key-f2-not
bit	OUT	input.0.key-f3
bit	OUT	input.0.key-f3-not
bit	OUT	input.0.key-f4
bit	OUT	input.0.key-f4-not
bit	OUT	input.0.key-f5
bit	OUT	input.0.key-f5-not
bit	OUT	input.0.key-f6
bit	OUT	input.0.key-f6-not
bit	OUT	input.0.key-f7
bit	OUT	input.0.key-f7-not
bit	OUT	input.0.key-f8
bit	OUT	input.0.key-f8-not
bit	OUT	input.0.key-f9
bit	OUT	input.0.key-f9-not
bit	OUT	input.0.key-g
bit	OUT	input.0.key-g-not
bit	OUT	input.0.key-grave
bit	OUT	input.0.key-grave-not
bit	OUT	input.0.key-h
bit	OUT	input.0.key-h-not
bit	OUT	input.0.key-home
bit	OUT	input.0.key-home-not
bit	OUT	input.0.key-i
bit	OUT	input.0.key-i-not
bit	OUT	input.0.key-insert
bit	OUT	input.0.key-insert-not
bit	OUT	input.0.key-j
bit	OUT	input.0.key-j-not
bit	OUT	input.0.key-k
bit	OUT	input.0.key-k-not
bit	OUT	input.0.key-kp0
bit	OUT	input.0.key-kp0-not
bit	OUT	input.0.key-kp1
bit	OUT	input.0.key-kp1-not
bit	OUT	input.0.key-kp2
bit	OUT	input.0.key-kp2-not
bit	OUT	input.0.key-kp3
bit	OUT	input.0.key-kp3-not
bit	OUT	input.0.key-kp4
bit	OUT	input.0.key-kp4-not
bit	OUT	input.0.key-kp5
bit	OUT	input.0.key-kp5-not
bit	OUT	input.0.key-kp6
bit	OUT	input.0.key-kp6-not
bit	OUT	input.0.key-kp7
bit	OUT	input.0.key-kp7-not
bit	OUT	input.0.key-kp8
bit	OUT	input.0.key-kp8-not
bit	OUT	input.0.key-kp9
bit	OUT	input.0.key-kp9-not
bit	OUT	input.0.key-kpasterisk
bit	OUT	input.0.key-kpasterisk-not
bit	OUT	input.0.key-kpdot
bit	OUT	input.0.key-kpdot-not
bit	OUT	input.0.key-kpenter
bit	OUT	input.0.key-kpenter-not
bit	OUT	input.0.key-kpminus
bit	OUT	input.0.key-kpminus-not
bit	OUT	input.0.key-kpplus
bit	OUT	input.0.key-kpplus-not
bit	OUT	input.0.key-kpslash
bit	OUT	input.0.key-kpslash-not
bit	OUT	input.0.key-l
bit	OUT	input.0.key-l-not
bit	OUT	input.0.key-left	Pad top
bit	OUT	input.0.key-left-not
bit	OUT	input.0.key-leftalt	Orange button
bit	OUT	input.0.key-leftalt-not
bit	OUT	input.0.key-leftbrace
bit	OUT	input.0.key-leftbrace-not
bit	OUT	input.0.key-leftctrl
bit	OUT	input.0.key-leftctrl-not
bit	OUT	input.0.key-leftmeta
bit	OUT	input.0.key-leftmeta-not
bit	OUT	input.0.key-leftshift	F11
bit	OUT	input.0.key-leftshift-not
bit	OUT	input.0.key-m
bit	OUT	input.0.key-m-not
bit	OUT	input.0.key-minus
bit	OUT	input.0.key-minus-not
bit	OUT	input.0.key-n
bit	OUT	input.0.key-n-not
bit	OUT	input.0.key-numlock
bit	OUT	input.0.key-numlock-not
bit	OUT	input.0.key-o
bit	OUT	input.0.key-o-not
bit	OUT	input.0.key-p
bit	OUT	input.0.key-p-not
bit	OUT	input.0.key-pagedown
bit	OUT	input.0.key-pagedown-not
bit	OUT	input.0.key-pageup
bit	OUT	input.0.key-pageup-not
bit	OUT	input.0.key-pause
bit	OUT	input.0.key-pause-not
bit	OUT	input.0.key-q	F2
bit	OUT	input.0.key-q-not
bit	OUT	input.0.key-r	F5
bit	OUT	input.0.key-r-not
bit	OUT	input.0.key-right	Pad bottom
bit	OUT	input.0.key-right-not
bit	OUT	input.0.key-rightalt
bit	OUT	input.0.key-rightalt-not
bit	OUT	input.0.key-rightbrace
bit	OUT	input.0.key-rightbrace-not
bit	OUT	input.0.key-rightctrl
bit	OUT	input.0.key-rightctrl-not
bit	OUT	input.0.key-rightmeta
bit	OUT	input.0.key-rightmeta-not
bit	OUT	input.0.key-rightshift
bit	OUT	input.0.key-rightshift-not
bit	OUT	input.0.key-s	F8
bit	OUT	input.0.key-s-not
bit	OUT	input.0.key-scrolllock
bit	OUT	input.0.key-scrolllock-not
bit	OUT	input.0.key-semicolon
bit	OUT	input.0.key-semicolon-not
bit	OUT	input.0.key-slash
bit	OUT	input.0.key-slash-not
bit	OUT	input.0.key-space	F15
bit	OUT	input.0.key-space-not
bit	OUT	input.0.key-sysrq
bit	OUT	input.0.key-sysrq-not
bit	OUT	input.0.key-t
bit	OUT	input.0.key-t-not
bit	OUT	input.0.key-tab	F1
bit	OUT	input.0.key-tab-not
bit	OUT	input.0.key-u
bit	OUT	input.0.key-u-not
bit	OUT	input.0.key-up	Pad right
bit	OUT	input.0.key-up-not
bit	OUT	input.0.key-v
bit	OUT	input.0.key-v-not
bit	OUT	input.0.key-w	F3
bit	OUT	input.0.key-w-not
bit	OUT	input.0.key-x	F13
bit	OUT	input.0.key-x-not
bit	OUT	input.0.key-y
bit	OUT	input.0.key-y-not
bit	OUT	input.0.key-z	F12
bit	OUT	input.0.key-z-not
bit	OUT	input.1.btn-middle	Wheel press
bit	OUT	input.1.btn-middle-not	… inverted
bit	OUT	input.1.btn-mouse
bit	OUT	input.1.btn-mouse-not
bit	OUT	input.1.btn-right
bit	OUT	input.1.btn-right-not
bit	IN	input.1.led-capsl	Green LED
bit	IN	input.1.led-capsl-invert
bit	IN	input.1.led-numl	Red LED
bit	IN	input.1.led-numl-invert
bit	IN	input.1.led-scrolll	Blue LED
bit	IN	input.1.led-scrolll-invert
s32	OUT	input.1.rel-wheel-counts	Scroll wheel
float	OUT	input.1.rel-wheel-position	=count/scale
bit	IN	input.1.rel-wheel-reset	Clear pos’n
float	IN	input.1.rel-wheel-scale	count→pos’n
s32	OUT	input.1.rel-x-counts
float	OUT	input.1.rel-x-position
bit	IN	input.1.rel-x-reset
float	IN	input.1.rel-x-scale
s32	OUT	input.1.rel-y-counts
float	OUT	input.1.rel-y-position
bit	IN	input.1.rel-y-reset
float	IN	input.1.rel-y-scale