Sensor ESP32

Intro

ESP32 to monitor different sensors in HX and displays data on LCD mounted under the machine.

It also sends the data to the other ESP using the ESP Now protocol.

Sensors for:

1.  Temperature Group Head

2. Temperature Boiler (thermocouple screwed down into outside of boiler)

3. Flow rate

4. Pressure sensor

Software at Gitlab

ESP Now 

to send data to Webserver ESP32

ESP's have a protocol called "ESP Now" that lets ESP32's and ESP8266's talk to each other over 2.4 GHz without going through a router.

But I couldn't get an ESP8266 to broadcast to a ESP32, so I used two ESP32's, and I have  can them broadcast to each other.

Random Nerd Tutorial ESP Now

There is extra code to figure out the wifi channel to use, and initialize wifi.  Its in mostly in setup.

Sensor ESP32 uses the mac address of the Webserver ESP32, so you need to figure out the mac address of the ESP32 used for webserver.  I put the mac address in the credentials.h file

The same structure needs to be in both ESP's, to format the data sent.  It lets the receiver figure out how to process the data. 

My structure is:

typedef struct struct_message {

    int Sid;

    double StempGroup;

    double StempBoiler;

    double Srate;       //ml/s from flowmeter

    double StotalML;    //total ml from flowmeter for this shot

    double Spressure;

    double Sweight;    //placeholder for weight

    int StimerPump;    //not used, used timer from start of flow instead

    int StimerFlow;

    int SreadingId;

} struct_message;

LCD

Used an 16x2 Ebay I2C LCD

If the link doesn't work, search for "i2c 16x2 lcd" on ebay, you should find plenty of choices.

Random Nerd LCD Tutorial

Easy to connect, uses +5VDC, so +5, ground, and two I2C wires, for clock (SCL) and data (SDA).

SDA connects to ESP32 GPIO 21 

SCL connects to ESP32 GPIO 22

VCC to ESP32 5V pin

GND to ground

Temperature Sensors

I built the temperature sensor part of this when I first bought the Expobar, around 10 years ago.  There were fewer options at the time, and I used a TC4 thermocouple interface board that is mostly used for coffee roasters.  I had one available.

Even though it has 4 inputs, I use two.  One is for grouphead temp, the other I have screwed into the boiler exterior.

This schematic is for a newer version of the board, with more features.  I just use the TC inputs and ambient temp sensor part of it

The J2 analog connector is where you connect the I2C lines.  

Power is 5V from ESP32 5V pin

Pressure sensor

Bought a "0-4.5V Stainless Steel Pressure Transducer Sender Sensor Oil Fuel 1/8NPT Air US" in the 200 psi version from ebay.

Link here, but ebay links expire, you can search for one on ebay.

200 psi = 13.8 bar, its output is: 0.5V~4.5V linear voltage output. 0 psi outputs 0.5V, 100 psi outputs 2.5V, and 200 psi outputs 4.5V

I calculated this will output 3.3V at 9.8 bar.  You don't want to go much over 3.3V to a ESP32 GPIO pin, so this works since my OPV will keep the pressure at about 9 bar max.

Based on this numbers, I calculated  how to convert, and use this in the program
PresBar = (MeasPres-660)/382;  //scale pressure sensor value to bar
The 660 is to account for 0.5V = 0 psi.  382 converts psi to bar.  Seems to be accurate, I get the same reading from this and from my analog pressure gauge.  

To install, I cut the teflon tubing after the OPV, and added a 6mm Tee connector.  The teflon tubing is 4mm x 6mm.

5508K162   Push-to-Connect Tube Fitting for Air and Water High-Temperature, Tee Connector, 6mm Tube OD

2129T25       5 feet of 4mm x 6mm fep tubing

5508K123       High-Temperature, Straight Adapter, 6mm Tube OD, 1/8 BSPT Male. (already had this)

This 1/8" FIP brass coupler fitting from Home Depot

So add the Push to Connect Tee somewhere inline with the teflon tubing coming out of the OPV (from pump out)

Add a piece of 6mm fep (teflon) tubing to top of tee, add 6mm to 1/8 BSPT Male adapter to other end of tube.

Male adapter goes to Home Depot coupler, and pressure sensor into other side of coupler.

Wiring

+5V to Red, Ground to black, GPIO to yellow

Flow Meter

https://www.aliexpress.us/item/3256805722047763.html?spm=a2g0o.detail.0.0.2b552f6aOVQkbO&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40000.327270.0&scm_id=1007.40000.327270.0&scm-url=1007.40000.327270.0&pvid=ba076755-6828-42ff-a70e-00196d2f632f&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.40000.327270.0,pvid:ba076755-6828-42ff-a70e-00196d2f632f,tpp_buckets:668%232846%238110%231995&pdp_npi=4%40dis%21USD%219.00%215.4%21%21%2165.00%21%21%402101c6e317001729200988505e4408%2112000034881498524%21rec%21US%21823979159%21 

.8 to 18 ml/s, 3V

Try a USN-HS06P

.7 to 2.5 ms/s

aliexpress

  Sensor: YF-S401

  https://bc-robotics.com/shop/liquid-flow-meter-yf-s401/

  Datasheet: outputs 5880 pulses per liter (approximately 1 pulse per 0.17mL

I measured it as 5298 pulses per liter, 1 pulse per 0.189ml.  So I set the cal factor to 5.298

    flowRate = ((1000.0 / (millis() - previousFlow)) * pulse1Sec) / calibrationFactor;

This is called about once per second. 
pulse1Sec is number of pulses since last call
previousFlow is time in millis when they was last called
result is in ml/sec

Bought a 932-9505-B Flow Meter from ebay

Datasheet link

There are many other similar models, I picked this one because it has the lowest linear flow rate, 0.033 l/min which is 33 ml/min or about 0.5 ml/sec  

On the graph for this model, the highest flow shown is 0.4 l/min.    Thats 400 ml/min or 6.7 ml/sec.  Much faster than I would want a shot to flow at.

I figured a shot flows in a range of 20-40 ml in 30 secs.   Easy math to use 30ml/30 secs or 1 ml/sec

Flow meter was added on the input side of the pump, between the pump and the water tank.

Horizontal position used, its when the contacts facing up

power supply +3.8 to +20 VDC

2382 pulses / liter

0.41 gr/pulse

Example code

Alternates here

May be able to find as replacement part for delonghi or other machines for less 

Case and Wiring

Bought the case and LCD bezel a long time ago

Bezel link (Mouser)

Don't remember where the case came from