Node-Red Admin Interface

Project: Retrofitted GoTo Dob – Pt4

Pt1 | Pt2 | Pt3 | Pt4

SHOW ME THE BUTTONS!!

Today’s the day we get a grip… we take a stand… we GET CONTROL.

“Node-RED is a tool for wiring together hardware devices, APIs and online services in new and interesting ways.” – node-red.org

We’re going to install Node-Red and a few plugins, then we can finally shift away from playing typey-typey on a keyboard and get some more standardised control of our motors. Once we reach the end of this step, you’ll be able to control your motors using a USB Game Controller, any mobile device, over the web, via SkySafari using the Nexstar protocol… we’ll have basically achieved pretty much the level of control of a Dual Axis motor driven scope, non-GoTo. (If you remember from Pt3, I can’t work on getting the GoTo part of things running until my motor feedback encoders have turned up).

Node-Red: The LEGO™ of Code.

As per Pt3, our Pi is now running headlessly, so plugin the 12v PSU from your DRV8835 board, give it a minute to boot, then connect using SSH.

Before we can install Node-Red, we need to install Node. To do this we need the download link, and the download link depends on which RaspberryPi you’re using. Open the Node download page. On there you’ll see 3x download links for Linux Binaries entitled ARMv6, ARMv7, and ARMv8.

You need to right click and select “copy link” / “copy shortcut” / “copy target” (all depends what browser you use) on the correct one for your particular Pi.

  • Raspberry Pi 1 Model A / A+ / B / B+, or Zero = ARMv6
  • Raspberry Pi 2 Model B = ARMv7
  • Raspberry Pi 3 Model B = ARMv8

In your SSH window type…

wget

… followed by a space, then right click > paste the copied link. Here’s what it looks like for me at the time of writing on my model B+

wget https://nodejs.org/dist/v6.9.2/node-v6.9.2-linux-armv6l.tar.xz

Bash enter, and it’ll download that file and we can extract it. To do that we need the filename part of the link! That’s everything after the final /. Then we need the same but without the .tar.xz on the end. Look over both bits of code and you’ll see what I mean.

tar -xvf node-v6.9.2-linux-armv6l.tar.xz
cd node-v6.9.2-linux-armv6l
sudo cp -R * /usr/local/

That’s Node installed, and this will also have installed the node package manager tool for us… npm.

The reason installing node like this is a pain is because it’s version number, the v.6.9.2 in the commands above, changes over time as they release new updates. However, doing it this way is much more reliable.

The npm tool makes installing Node packages such as Node-Red MUCH simpler. You can copy and paste the code exactly from here on as there are no version numbers that are likely to change. Just copy and paste each line, hitting enter after each.

sudo npm cache clean
sudo npm install -g --unsafe-perm node-red

Now, if you’re doing this on a Mobile B+ or earlier go and amuse yourself for an hour or two. Installing Node-Red takes a LONG time on the more basic Raspberrys. On my Model B+, I managed a cigarette, breakfast, coffee and a shower in the time it took to complete. If you’re doing it on a Pi3, it’ll probably rattle through whilst you make a quick brew.

Once that’s done, run the next lump of commands. These download some scripts which make node-red start automagically when you fire up your Pi.

sudo wget https://raw.githubusercontent.com/node-red/raspbian-deb-package/master/resources/nodered.service -O /lib/systemd/system/nodered.service
sudo wget https://raw.githubusercontent.com/node-red/raspbian-deb-package/master/resources/node-red-start -O /usr/bin/node-red-start
sudo wget https://raw.githubusercontent.com/node-red/raspbian-deb-package/master/resources/node-red-stop -O /usr/bin/node-red-stop
sudo chmod +x /usr/bin/node-red-st*
sudo systemctl daemon-reload

Next we need to edit the /lib/systemd/system/nodered.service and tell it that user=root.

pico /lib/systemd/system/nodered.service

Use the arrow keys to move down to this line:

User=pi

and change it to

User=root

To save the changes and quit the editor, press Ctrl + O followed by Ctrl + X.

Now run the following commands which enable Node-Red, and install a few necessary plugins to allow us to control things attached to the Pi’s GPIO pins (ie: our DRV8835):

sudo systemctl enable nodered.service
cd ~/
git clone git://git.drogon.net/wiringPi
cd wiringPi
./build
cd ~/
sudo npm install -g raspi-io --unsafe-perm --force
sudo npm install -g node-red-contrib-gpio --unsafe-perm --force
sudo npm install -g node-red-contrib-admin --unsafe-perm
sudo npm install -g node-red-dashboard --unsafe-perm
sudo passwd root      {set a password when prompted!}
su                    {enter the password when prompted!}
mkdir ~/.node-red && cd ~/.node-red
npm install wiring-pi --unsafe-perm
npm install node-red-node-base64

We need to make a tweak to a file that was installed during the above next…

pico settings.js

Use the arrow keys to move down to a line containing the following:

	functionGlobalContext: {

and add a line directly beneath it as follows:

	    wpi: require('wiring-pi’)

Ctrl + O to save, Ctrl + X to exit.

And now, finally, run the following…

exit
sudo reboot

You can breathe now. That’s pretty much the last time we’ll need to anything major on the commandline with a bit of luck. Give it a few minutes to reboot and for everything to start, and then fire up a web browser, and navigate to our device using the name we set in Pt3, the same name we used for our SSH connection… on port 1880.

http://scope.local:1880/

You should be presented with a view somewhat similar to this… WELCOME TO NODE-RED!
node-red

Now let’s get the logic in place for doing some controlling! Select all of the code below, and copy.

[
    {
        "id": "ce01dcb1.0d0708",
        "type": "ui_slider",
        "z": "6e9dcce8.16d0ac",
        "name": "Speed",
        "label": "PWM Speed",
        "group": "529fa907.5b11e8",
        "order": 2,
        "width": "",
        "height": "",
        "passthru": true,
        "topic": "",
        "min": 0,
        "max": "480",
        "step": "",
        "x": 1550,
        "y": 100,
        "wires": [
            [
                "2033a63e.1db752",
                "768f7064.9ee06",
                "17540ba2.acbf54"
            ]
        ]
    },
    {
        "id": "593500d9.472898",
        "type": "ui_slider",
        "z": "6e9dcce8.16d0ac",
        "name": "Speed",
        "label": "PWM Speed",
        "group": "16013277.c83b7e",
        "order": 2,
        "width": "",
        "height": "",
        "passthru": true,
        "topic": "",
        "min": 0,
        "max": "480",
        "step": "",
        "x": 1550,
        "y": 460,
        "wires": [
            [
                "8f81d77d.913248",
                "57bd08e3.4074e",
                "f1d65120.e97d88"
            ]
        ]
    },
    {
        "id": "321f9e0a.7d180a",
        "type": "ui_switch",
        "z": "6e9dcce8.16d0ac",
        "name": "Direction",
        "label": "Direction",
        "group": "529fa907.5b11e8",
        "order": 4,
        "width": "",
        "height": "",
        "passthru": true,
        "topic": "",
        "onvalue": "1",
        "onvalueType": "num",
        "onicon": "",
        "oncolor": "",
        "offvalue": "0",
        "offvalueType": "num",
        "officon": "",
        "offcolor": "",
        "x": 1400,
        "y": 280,
        "wires": [
            [
                "645e68f.4975798"
            ]
        ]
    },
    {
        "id": "652d3f0e.09ae2",
        "type": "ui_switch",
        "z": "6e9dcce8.16d0ac",
        "name": "Direction",
        "label": "Direction",
        "group": "16013277.c83b7e",
        "order": 4,
        "width": "",
        "height": "",
        "passthru": true,
        "topic": "",
        "onvalue": "1",
        "onvalueType": "num",
        "onicon": "",
        "oncolor": "",
        "offvalue": "0",
        "offvalueType": "num",
        "officon": "",
        "offcolor": "",
        "x": 1380,
        "y": 640,
        "wires": [
            [
                "afe2732b.c81f78"
            ]
        ]
    },
    {
        "id": "645e68f.4975798",
        "type": "rpi-gpio out",
        "z": "6e9dcce8.16d0ac",
        "name": "Motor 1 Direction",
        "pin": "29",
        "set": true,
        "level": "1",
        "out": "out",
        "x": 1750,
        "y": 280,
        "wires": []
    },
    {
        "id": "afe2732b.c81f78",
        "type": "rpi-gpio out",
        "z": "6e9dcce8.16d0ac",
        "name": "Motor 2 Direction",
        "pin": "31",
        "set": true,
        "level": "1",
        "out": "out",
        "x": 1750,
        "y": 640,
        "wires": []
    },
    {
        "id": "6ff502aa.0b4db4",
        "type": "inject",
        "z": "6e9dcce8.16d0ac",
        "name": "Init 1",
        "topic": "",
        "payload": "1",
        "payloadType": "num",
        "repeat": "",
        "crontab": "",
        "once": true,
        "x": 90,
        "y": 160,
        "wires": [
            [
                "5f3a8643.d01b28",
                "a2f35daf.c5eab"
            ]
        ]
    },
    {
        "id": "2033a63e.1db752",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Motor 1 Speed",
        "func": "var pin = 26;\nvar wpi = context.global.wpi;\nwpi.wiringPiSetup();\nwpi.pinMode(pin, wpi.PWM_OUTPUT);\nwpi.pwmSetMode(wpi.PWM_MODE_MS);\nwpi.pwmSetRange(480);\nwpi.pwmSetClock(2);\nif(msg.payload){\n    wpi.pwmWrite(pin, parseInt(msg.payload));\n} else {\n    wpi.pwmWrite(pin, 0);\n}\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 1740,
        "y": 100,
        "wires": [
            []
        ]
    },
    {
        "id": "8f81d77d.913248",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Motor 2 Speed",
        "func": "var pin2 = 23;\nvar wpi = context.global.wpi;\nwpi.wiringPiSetup();\nwpi.pinMode(pin2, wpi.PWM_OUTPUT);\nwpi.pwmSetMode(wpi.PWM_MODE_MS);\nwpi.pwmSetRange(480);\nwpi.pwmSetClock(2);\nif(msg.payload){\n    wpi.pwmWrite(pin2, parseInt(msg.payload));\n} else {\n    wpi.pwmWrite(pin2, 0);\n}\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 1740,
        "y": 460,
        "wires": [
            []
        ]
    },
    {
        "id": "a4ae907d.6bb7f8",
        "type": "ui_chart",
        "z": "6e9dcce8.16d0ac",
        "name": "Motor 2 (Y / Alt / DEC)",
        "group": "16013277.c83b7e",
        "order": 5,
        "width": "",
        "height": "",
        "label": "Alt Axis",
        "chartType": "line",
        "xformat": "HH:mm:ss",
        "interpolate": "basis",
        "nodata": "No Data",
        "ymin": "-480",
        "ymax": "480",
        "removeOlder": "5",
        "removeOlderPoints": "",
        "removeOlderUnit": "60",
        "cutout": "",
        "x": 1930,
        "y": 419,
        "wires": [
            [],
            []
        ]
    },
    {
        "id": "3e5949e7.deb77e",
        "type": "ui_chart",
        "z": "6e9dcce8.16d0ac",
        "name": "Motor 1 (X / Az / RA)",
        "group": "529fa907.5b11e8",
        "order": 5,
        "width": "",
        "height": "",
        "label": "Az Axis",
        "chartType": "line",
        "xformat": "HH:mm:ss",
        "interpolate": "basis",
        "nodata": "No Data",
        "ymin": "-480",
        "ymax": "480",
        "removeOlder": "5",
        "removeOlderPoints": "",
        "removeOlderUnit": "60",
        "cutout": "",
        "x": 1936,
        "y": 58,
        "wires": [
            [],
            []
        ]
    },
    {
        "id": "f822aab.d15f158",
        "type": "debug",
        "z": "6e9dcce8.16d0ac",
        "name": "Current Speed",
        "active": false,
        "console": "false",
        "complete": "payload",
        "x": 900,
        "y": 200,
        "wires": []
    },
    {
        "id": "bcf80c97.cf8bb",
        "type": "HIDdevice",
        "z": "6e9dcce8.16d0ac",
        "connection": "2ea0db0d.dcda1c",
        "name": "Gamepad",
        "x": 100,
        "y": 240,
        "wires": [
            [
                "1b8ddc4f.6f8d8c"
            ],
            []
        ]
    },
    {
        "id": "61c8dccf.8e230c",
        "type": "switch",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "property": "payload",
        "propertyType": "msg",
        "rules": [
            {
                "t": "cont",
                "v": "20",
                "vt": "str"
            },
            {
                "t": "cont",
                "v": "10",
                "vt": "str"
            },
            {
                "t": "else"
            }
        ],
        "checkall": "true",
        "outputs": 3,
        "x": 470,
        "y": 240,
        "wires": [
            [
                "205dff56.1dbc5"
            ],
            [
                "205dff56.1dbc5"
            ],
            [
                "1fe4527a.912056"
            ]
        ]
    },
    {
        "id": "1b8ddc4f.6f8d8c",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "BufferHex to String",
        "func": "msg.payload = msg.payload.toString('hex');\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 290,
        "y": 240,
        "wires": [
            [
                "61c8dccf.8e230c"
            ]
        ]
    },
    {
        "id": "205dff56.1dbc5",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "MotorSpeed Logic",
        "func": "var stepsize = 22;\nvar currspeed = global.get(\"motorspeed\");\nif (msg.payload.slice(-2) == \"20\"||msg.payload.slice(-2)==\"20\") {\n    currspeed = currspeed + stepsize;\n} else if (msg.payload.slice(-2) == \"10\"||msg.payload.slice(-2)==\"10\") {\n    currspeed = currspeed - stepsize;\n}\nif (currspeed = 480) {\n    currspeed = 480\n}\nglobal.set(\"motorspeed\", currspeed);\nmsg.payload = currspeed;\nvar log = {};\nif (currspeed == 22) {\n    log.payload = \"Motor Speed now \"+currspeed+\" (MIN)\";\n} else if (currspeed == 480) {\n    log.payload = \"Motor Speed now \"+currspeed+\" (MAX)\";\n} else {\n    log.payload = \"Motor Speed now \"+currspeed;\n}\n\nreturn [msg,log];",
        "outputs": "2",
        "noerr": 0,
        "x": 670,
        "y": 200,
        "wires": [
            [
                "86292b52.9330b"
            ],
            [
                "f822aab.d15f158"
            ]
        ]
    },
    {
        "id": "5f3a8643.d01b28",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Init Global Vars",
        "func": "global.set(\"motorspeed\",44);\nglobal.set(\"m1dir\",1);\nglobal.set(\"m2dir\",1);",
        "outputs": 1,
        "noerr": 0,
        "x": 280,
        "y": 100,
        "wires": [
            []
        ]
    },
    {
        "id": "1fe4527a.912056",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Motor Direction Handler",
        "func": "var mg1, mg2, m1={}, m2={}, m3={}, m4={}, m5={}, m6={}, v = 0;\nvar speed = global.get(\"motorspeed\");\nif (msg.payload == '3f0000'){\n    global.set(\"m2dir\",1);\n    m6.payload = speed;\n    v = 1;\n}\nif (msg.payload == '3f7f00'){\n    global.set(\"m2dir\",0);\n    m6.payload = speed;\n    v = 1;\n}\nif (msg.payload == '7f3f00'){\n    global.set(\"m1dir\",1);\n    m5.payload = speed;\n    v = 1;\n}\nif (msg.payload == '003f00'){\n    global.set(\"m1dir\",0);\n    m5.payload = speed;\n    v = 1;\n}\nif (msg.payload == '7f0000'){\n    global.set(\"m1dir\",1);\n    global.set(\"m2dir\",1);\n    m5.payload = speed;\n    m6.payload = speed;\n    v = 1;\n}\nif (msg.payload == '7f7f00'){\n    global.set(\"m1dir\",1);\n    global.set(\"m2dir\",0);\n    m5.payload = speed;\n    m6.payload = speed;\n    v = 1;\n}\nif (msg.payload == '007f00'){\n    global.set(\"m1dir\",0);\n    global.set(\"m2dir\",0);\n    m5.payload = speed;\n    m6.payload = speed;\n    v = 1;\n}\nif (msg.payload == '000000'){\n    global.set(\"m1dir\",0);\n    global.set(\"m2dir\",1);\n    m5.payload = speed;\n    m6.payload = speed;\n    v = 1;\n}\nif (msg.payload == '3f3f00'){\n    global.set(\"m1dir\",1);\n    global.set(\"m2dir\",1);\n\n//    m5.payload = speed;\n//    m6.payload = speed;\n    v = 1;\n}\nif (v == 1) {\n    var gm1 = global.get(\"m1dir\");\n    if (gm1 == 1) {\n        mg1 = \"Forward\";\n    } else {\n        mg1 = \"Reverse\";\n    }\n    var gm2 = global.get(\"m2dir\");\n    if (gm2 == 1) {\n        mg2 = \"Forward\";\n    } else {\n        mg2 = \"Reverse\";\n    }\n    m1.payload = \"M1 Direction: \" + mg1;\n    m2.payload = \"M2 Direction: \" + mg2;\n    m3.payload = gm1;\n    m4.payload = gm2;\n    return [m5,m3,m2,m1,m6,m4];\n}",
        "outputs": "6",
        "noerr": 0,
        "x": 850,
        "y": 300,
        "wires": [
            [
                "4e4b9c11.53474c",
                "768f7064.9ee06",
                "17540ba2.acbf54"
            ],
            [
                "321f9e0a.7d180a"
            ],
            [],
            [],
            [
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                "57bd08e3.4074e",
                "f1d65120.e97d88"
            ],
            [
                "652d3f0e.09ae2"
            ]
        ]
    },
    {
        "id": "a2f35daf.c5eab",
        "type": "getHIDdevices",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "x": 260,
        "y": 160,
        "wires": [
            [
                "75a0a8aa.300fc"
            ]
        ]
    },
    {
        "id": "75a0a8aa.300fc",
        "type": "debug",
        "z": "6e9dcce8.16d0ac",
        "name": "Connected HID Devices",
        "active": true,
        "console": "false",
        "complete": "payload",
        "x": 490,
        "y": 160,
        "wires": []
    },
    {
        "id": "86292b52.9330b",
        "type": "ui_text",
        "z": "6e9dcce8.16d0ac",
        "group": "f50f09aa.7b4da",
        "order": 3,
        "width": "",
        "height": "",
        "name": "Controller Motor Speed",
        "label": "Current PWM Speed",
        "format": "{{msg.payload}}",
        "layout": "",
        "x": 930,
        "y": 160,
        "wires": []
    },
    {
        "id": "768f7064.9ee06",
        "type": "ui_text",
        "z": "6e9dcce8.16d0ac",
        "group": "529fa907.5b11e8",
        "order": 3,
        "width": "",
        "height": "",
        "name": "Motor 1 Speed",
        "label": "Current Speed",
        "format": "{{msg.payload}}",
        "layout": "",
        "x": 1740,
        "y": 180,
        "wires": []
    },
    {
        "id": "57bd08e3.4074e",
        "type": "ui_text",
        "z": "6e9dcce8.16d0ac",
        "group": "16013277.c83b7e",
        "order": 3,
        "width": "",
        "height": "",
        "name": "Motor 2 Speed",
        "label": "Current Speed",
        "format": "{{msg.payload}}",
        "layout": "",
        "x": 1740,
        "y": 380,
        "wires": []
    },
    {
        "id": "ed9ae77.7edd498",
        "type": "inject",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "topic": "",
        "payload": "44",
        "payloadType": "num",
        "repeat": "",
        "crontab": "",
        "once": true,
        "x": 710,
        "y": 160,
        "wires": [
            [
                "86292b52.9330b"
            ]
        ]
    },
    {
        "id": "5a9c05a4.5961f4",
        "type": "inject",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "topic": "",
        "payload": "0",
        "payloadType": "num",
        "repeat": "",
        "crontab": "",
        "once": true,
        "x": 1550,
        "y": 340,
        "wires": [
            [
                "57bd08e3.4074e",
                "5eafacb5.382f3c"
            ]
        ]
    },
    {
        "id": "8f2d52f7.f91cd",
        "type": "ui_text",
        "z": "6e9dcce8.16d0ac",
        "group": "f50f09aa.7b4da",
        "order": 4,
        "width": "",
        "height": "",
        "name": "Usable Speed Range",
        "label": "Usable Speed Range",
        "format": "22 - 480",
        "layout": "",
        "x": 140,
        "y": 40,
        "wires": []
    },
    {
        "id": "625d1cf9.254094",
        "type": "switch",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "property": "payload",
        "propertyType": "msg",
        "rules": [
            {
                "t": "nnull"
            },
            {
                "t": "else"
            }
        ],
        "checkall": "true",
        "outputs": 2,
        "x": 1230,
        "y": 460,
        "wires": [
            [
                "593500d9.472898"
            ],
            [
                "6dabfb5b.61488c"
            ]
        ]
    },
    {
        "id": "4e4b9c11.53474c",
        "type": "switch",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "property": "payload",
        "propertyType": "msg",
        "rules": [
            {
                "t": "nnull"
            },
            {
                "t": "else"
            }
        ],
        "checkall": "true",
        "outputs": 2,
        "x": 1170,
        "y": 100,
        "wires": [
            [
                "ce01dcb1.0d0708"
            ],
            [
                "f830102a.e33688"
            ]
        ]
    },
    {
        "id": "6dabfb5b.61488c",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Stop",
        "func": "msg.payload = 0;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 1390,
        "y": 480,
        "wires": [
            [
                "593500d9.472898"
            ]
        ]
    },
    {
        "id": "f830102a.e33688",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Stop",
        "func": "msg.payload = 0;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 1310,
        "y": 120,
        "wires": [
            [
                "ce01dcb1.0d0708"
            ]
        ]
    },
    {
        "id": "ab520a48.2e36f8",
        "type": "inject",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "topic": "",
        "payload": "0",
        "payloadType": "num",
        "repeat": "",
        "crontab": "",
        "once": true,
        "x": 1550,
        "y": 240,
        "wires": [
            [
                "768f7064.9ee06",
                "22baf9b8.3b14ce"
            ]
        ]
    },
    {
        "id": "fabe2704.90897",
        "type": "inject",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "topic": "",
        "payload": "1",
        "payloadType": "num",
        "repeat": "",
        "crontab": "",
        "once": true,
        "x": 1250,
        "y": 320,
        "wires": [
            [
                "321f9e0a.7d180a"
            ]
        ]
    },
    {
        "id": "6b84fa1d.1f5e74",
        "type": "inject",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "topic": "",
        "payload": "1",
        "payloadType": "num",
        "repeat": "",
        "crontab": "",
        "once": true,
        "x": 1210,
        "y": 640,
        "wires": [
            [
                "652d3f0e.09ae2"
            ]
        ]
    },
    {
        "id": "78bbbaaa.159494",
        "type": "link in",
        "z": "6e9dcce8.16d0ac",
        "name": "Nexstar Motor Receiver",
        "links": [
            "dd2234e7.8d6228",
            "1bf4eeb.c5f9211"
        ],
        "x": 215,
        "y": 300,
        "wires": [
            [
                "8f75bcab.a520c"
            ]
        ]
    },
    {
        "id": "8f75bcab.a520c",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Nexstar Motor Parser",
        "func": "var payload = msg.payload.split(\"x\");\nif (payload[0]=='M1' && payload[1]=='1'){\n    msg.payload=\"3f0000\";\n}\nif (payload[0]=='M1' && payload[1]=='0'){\n    msg.payload=\"3f7f00\";\n}\nif (payload[0]=='M2' && payload[1]=='1'){\n    msg.payload=\"7f3f00\";\n}\nif (payload[0]=='M2' && payload[1]=='0'){\n    msg.payload=\"003f00\";\n}\nglobal.set(\"motorspeed\",payload[2]);\nreturn msg;",
        "outputs": "1",
        "noerr": 0,
        "x": 420,
        "y": 300,
        "wires": [
            [
                "1fe4527a.912056"
            ]
        ]
    },
    {
        "id": "aba9d692.9e9578",
        "type": "tcp in",
        "z": "6e9dcce8.16d0ac",
        "name": "Nexstar In",
        "server": "server",
        "host": "",
        "port": "4030",
        "datamode": "stream",
        "datatype": "utf8",
        "newline": "",
        "topic": "",
        "base64": false,
        "x": 80,
        "y": 500,
        "wires": [
            [
                "9f0f41a.b40c4c",
                "ba604dc1.013278"
            ]
        ]
    },
    {
        "id": "7ac85152.5f29b",
        "type": "tcp out",
        "z": "6e9dcce8.16d0ac",
        "host": "",
        "port": "",
        "beserver": "reply",
        "base64": false,
        "end": false,
        "name": "reply to Nexstar",
        "x": 560,
        "y": 500,
        "wires": []
    },
    {
        "id": "9f0f41a.b40c4c",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "Nexstar Protocol",
        "func": "if (msg.payload == \"V#\"){\n    // SS sends V#\n    // Respond with 23# (for v2.3)\n    data = \"23#\";\n}\nif (msg.payload == \"t\"){\n    // SS sends t#\n    // Respond with 1# (Alt/Az)\n    // Options: 0 = Off\n    //          1 = Alt/Az\n    //          2 = EQ North\n    //          3 = EQ South\n    data = \"49#\";\n}\nif (msg.payload == \"e\"){\n    // SS sends e#\n    data = \"34AB0500,12CE0500#\";\n}\nmsg.payload = data;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 310,
        "y": 500,
        "wires": [
            [
                "7ac85152.5f29b"
            ]
        ]
    },
    {
        "id": "ba604dc1.013278",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "filter for motor cmd",
        "func": "if(!String.prototype.startsWith){\n    String.prototype.startsWith = function (str) {\n        return !this.indexOf(str);\n    }\n}\nif (msg.payload !== \"e\"){\n    if (msg.payload.startsWith('P')){\n        return msg;\n    }\n    if (msg.payload == \"M\"){\n        global.set(\"motorspeed\",0);\n    }\n}",
        "outputs": "1",
        "noerr": 0,
        "x": 310,
        "y": 560,
        "wires": [
            [
                "d436423.a85394",
                "54c6b28f.c778a4"
            ]
        ]
    },
    {
        "id": "e888f7a5.5f1bb",
        "type": "base64",
        "z": "6e9dcce8.16d0ac",
        "name": "b64 encode",
        "x": 634,
        "y": 560,
        "wires": [
            [
                "32e73aa3.b9996e"
            ]
        ]
    },
    {
        "id": "32e73aa3.b9996e",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "parse motor cmd",
        "func": "var axis = msg.payload.substr(3,1);\nvar dire = msg.payload.substr(5,1);\nvar sped = msg.payload.substr(6,1);\nif (sped == 'I') {\n    sped = '120'; //guiding\n} else if (sped == 'U') {\n    sped = '240'; //centering\n} else if (sped == 'c') {\n    sped = '360'; //finding\n} else if (sped == 'k') {\n    sped = '480'; //max!\n} else if (sped == 'A') {\n    sped = '0';\n}\nsped = ' '+sped;\n\nif (axis == 'R' && dire == 'A'){\n    msg.payload = \"M1x1x\"+sped;\n} else if (axis == 'R' && dire == 'Q'){\n    msg.payload = \"M1x0x\"+sped;\n} else if (axis == 'Q' && dire == 'A'){\n    msg.payload = \"M2x1x\"+sped;\n} else if (axis == 'Q' && dire == 'Q'){\n    msg.payload = \"M2x0x\"+sped;\n}\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 814,
        "y": 560,
        "wires": [
            [
                "1bf4eeb.c5f9211"
            ]
        ]
    },
    {
        "id": "1bf4eeb.c5f9211",
        "type": "link out",
        "z": "6e9dcce8.16d0ac",
        "name": "Nexstar Motor Control",
        "links": [
            "78bbbaaa.159494"
        ],
        "x": 959,
        "y": 560,
        "wires": []
    },
    {
        "id": "78dbe29a.3bb26c",
        "type": "comment",
        "z": "6e9dcce8.16d0ac",
        "name": "Nexstar Remote",
        "info": "This module handles Nexstar Serial Protocol over TCP,\notherwise known as \"SkyFi\".\n\nSimply connect to scope.local with port 4030",
        "x": 100,
        "y": 460,
        "wires": []
    },
    {
        "id": "d436423.a85394",
        "type": "switch",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "property": "payload",
        "propertyType": "msg",
        "rules": [
            {
                "t": "nnull"
            }
        ],
        "checkall": "true",
        "outputs": 1,
        "x": 481.5,
        "y": 560,
        "wires": [
            [
                "e888f7a5.5f1bb"
            ]
        ]
    },
    {
        "id": "54c6b28f.c778a4",
        "type": "switch",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "property": "payload",
        "propertyType": "msg",
        "rules": [
            {
                "t": "nnull"
            }
        ],
        "checkall": "true",
        "outputs": 1,
        "x": 482,
        "y": 615,
        "wires": [
            [
                "3651e217.e9b266"
            ]
        ]
    },
    {
        "id": "3651e217.e9b266",
        "type": "debug",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "active": true,
        "console": "false",
        "complete": "true",
        "x": 616.5,
        "y": 615,
        "wires": []
    },
    {
        "id": "22baf9b8.3b14ce",
        "type": "ui_gauge",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "group": "529fa907.5b11e8",
        "order": 1,
        "width": 0,
        "height": 0,
        "gtype": "gage",
        "title": "Az Speed",
        "label": "PWM Drive",
        "format": "{{value}}",
        "min": "-480",
        "max": "480",
        "colors": [
            "#CA3838",
            "#00B500",
            "#CA3838"
        ],
        "x": 1961.5,
        "y": 99,
        "wires": []
    },
    {
        "id": "5eafacb5.382f3c",
        "type": "ui_gauge",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "group": "16013277.c83b7e",
        "order": 1,
        "width": 0,
        "height": 0,
        "gtype": "gage",
        "title": "Az Speed",
        "label": "PWM Drive",
        "format": "{{value}}",
        "min": "-480",
        "max": "480",
        "colors": [
            "#CA3838",
            "#00B500",
            "#CA3838"
        ],
        "x": 1914,
        "y": 338,
        "wires": []
    },
    {
        "id": "17540ba2.acbf54",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "func": "if (global.get(\"m1dir\")==0) {\n    msg.payload = msg.payload*(-1);\n}\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 1707.5,
        "y": 58,
        "wires": [
            [
                "3e5949e7.deb77e",
                "22baf9b8.3b14ce"
            ]
        ]
    },
    {
        "id": "f1d65120.e97d88",
        "type": "function",
        "z": "6e9dcce8.16d0ac",
        "name": "",
        "func": "if (global.get(\"m2dir\")==0) {\n    msg.payload = msg.payload*(-1);\n}\nreturn msg; ",
        "outputs": 1,
        "noerr": 0,
        "x": 1711,
        "y": 420,
        "wires": [
            [
                "a4ae907d.6bb7f8",
                "5eafacb5.382f3c"
            ]
        ]
    },
    {
        "id": "529fa907.5b11e8",
        "type": "ui_group",
        "z": "",
        "name": "Motor 1 (Azimuth)",
        "tab": "49822692.fee8a8",
        "order": null,
        "disp": true,
        "width": "6"
    },
    {
        "id": "16013277.c83b7e",
        "type": "ui_group",
        "z": "",
        "name": "Motor 2 (Altitude)",
        "tab": "49822692.fee8a8",
        "order": 5,
        "disp": true,
        "width": "6"
    },
    {
        "id": "2ea0db0d.dcda1c",
        "type": "HIDConfig",
        "z": "",
        "vid": "1118",
        "pid": "39",
        "name": "Gamepad"
    },
    {
        "id": "f50f09aa.7b4da",
        "type": "ui_group",
        "z": "",
        "name": "Gamepad Control",
        "tab": "49822692.fee8a8",
        "order": 5,
        "disp": true,
        "width": "6"
    },
    {
        "id": "49822692.fee8a8",
        "type": "ui_tab",
        "z": "",
        "name": "Drive",
        "icon": "dashboard",
        "order": 0
    }
]

Now head to Node-Red, click the menu button in the top right corner, and choose Import > Clipboard. Paste in the box and hit the Import button then finally hit the large Deploy button. You should now see THIS:

theflow

Open a new tab in a web browser, or pick up your mobile connected to the same network, and head to…

http://scope.local:1880/ui

…and behold! A responsive web interface for our motor controller which will work on any mobile device on the same network! Use the PWM Sliders to set the motor speed, and the direction switches to set the motor direction.

node-red-ui

 

As an added bonus, if you’re a SkySafari user, you can configure it as follows, and the slew and rate buttons will function perfectly as the Node-Red flow I’ve provided also handles the basics of Celestron’s Nexstar Protocol…

 

skysafari

 

For USB Gamepad control, you need to connect up your gamepad, then restart the Raspberry Pi. When you return to Node-Red, head to the menu button in the top right corner, and select View > Debug Messages. Your gamepad should be detected towards the top, and should have a message listing it’s VendorID and ProductID (for mine these are 1118 and 39)

usbhid

Note these values down, then double click on the “Gamepad” node… click it’s pencil button, and enter the Vendor ID as VID and the Product ID as PID, and hit the Update button… then hit the Deploy button in the top right corner of Node-Red.

usbhid2

 

Head back to the web user interface at http://scope.local:1880/ui/, pick up your gamepad, and see if things work!

 

 

Sadly that’s about as much as we can do with our controller for this year… so I shall see you in 2017 with a fresh pair of encoders, and then we can look at setting accurate tracking rates (this should be somewhere around 25 on Motor 1’s PWM Slider based on the gearbox calcs etc back in Pt1 – if you get bored, see if you can work out how to add a sidereal switch to trigger a message payload of 25 to motor1!), adding alignment and GoTo functionality, and possibly integrated guiding via lin-guider. Have a happy whatever-festive-crap-you-celebrate holiday!! I shall be here, with my astro gear, getting downright dirty!

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