Howto: Minimum VSCP wifi Level II node (VSCP PID detector)

In this  howto we will build a simple VSCP level II node that with the help of a PIR motion sensor detects motion and sends this as a VSCP event wireless to a VSCP daemon.

We use the famous ESP8266  for this  and work in the even more famous Arduino environment.  The ESP8266 comes in many flavors but a convenient form factor is the NodeMCU board.  You can buy it on Aliexpress or Ebay at a low-cost (USD 2.2).

There is also a baseboard available for the NodeMCU and I use it as it is convenient when working with a new design. It to is available on Aliexpress and Ebay at a low-cost (USD 1.54).

The last item you need is the PIR sensor, they to are available at low-cost. I bought mine from Ebay (USD 0.99).

If you haven’t set up your Arduino IDE for work with the ESP8266 you need to do that now.  Here is an excellent tutorial on how to do this. Make the blink example work before you move on.

I find the Arduino IDE a bit crude to work with so I use Visual Studio Code instead.  An excellent programming editor that works on all the major operation systems. I tend to use it more and more. But there are other options to such as Atom. Anyway instructions on how to get it working for Arduino development is here.  Make sure to set the “output” tag to a valid location in the .vscode/arduino.json file otherwise upload will be VERY slow.

You also need a VSCP daemon/server running for this example. All info about it is here.

To connect the sensor to the NodeMCU we need to know about he port mapping for the module which is a bit different from for other Arduino devices. It looks like this

static const uint8_t D0   = 16;
static const uint8_t D1   = 5;
static const uint8_t D2   = 4;
static const uint8_t D3   = 0;
static const uint8_t D4   = 2;
static const uint8_t D5   = 14;
static const uint8_t D6   = 12;
static const uint8_t D7   = 13;
static const uint8_t D8   = 15;
static const uint8_t D9   = 3;
static const uint8_t D10  = 1;

D0 has a blue LED connected to it so it is an obvious candidate for status. D1 can be used to connect to the PIR

The PIR device I have outputs a 3V signal even when powered with +5V so it is OK to connect directly to D1. So the three pins on the PIR

1     +5V
2     Output to D1 (High on detect)
3     GND

The LED on D0 light up when a LOW is written to it. This is opposite to the PIR output. We take care of this in software.

We implement a dump VSCP device here. This is a device that does not handle any of the register reads that “normal” VSCP requires and which don’t have a MDF file either. A dumb device has bit 14 set in the header.

We send two events. The heartbeat event (CLASS1.INFORMATION, Type=9) every minute. This event is recommended for all nodes as it is used for node discovery and detection. The other event we send is the detect event (CLASS1.INFORMATION, Type=49 detect) when an object is detected.

The test setup looks like this

and you can find the complete code is here

The heartbeat coming into the VSCP daemon (using VSCP works)

and the detect event

With the event in the VSCP daemon it is easy to add a DM row that for instance light up the lamps in a room. You can also use the rest or the websocket interface to do give visual feedback.

We will follow-up this howto with a post where we use the Expressif SDK instead of the Arduino and use a plain ESP8266 board. But also a ost where we implement a full Level II node that have registers and a MDF and show the advantage we get with a node like that over a dumb one.

An alternative wifi lib is documented here.