How to use Sun Path Finder

Sun path diagrams can tell you a lot about how the sun will impact your site and building throughout the year. Stereographic sun path diagrams can be used to read the solar azimuth and altitude for a given location. Sun path finder is a device that helps you to read the Stereographic Sun Path Diagrams ans shading analysis.

Azimuth Lines - Azimuth angles run around the edge of the diagram.

Altitude Lines - Altitude angles are represented as concentric circular dotted lines that run from the centre of the diagram out.

Date Lines - Date lines start on the eastern side of the graph and run to the western side and represent the path of the sun on one particular day of the year.

Hour Lines - Hour lines are shown as figure-eight-type lines that intersect the date lines and represent the position of the sun at a specific hour of the day. The intersection points between date and hour lines give the position of the sun.

Step by Step Guide to use Sun Path Finder:

1. Locate the required hour line on the diagram. 

2. Locate the required date line, remembering that solid are used for Jan-June and dotted lines for July-Dec. 

3. Find the intersection point of the hour and date lines. Remember to intersect solid with solid and dotted with dotted lines. 

4. Draw a line from the very centre of the diagram, through the intersection point, out to the perimeter of the diagram. 

5. Read the azimuth as an angle taken clockwise from north. In this case, the value is about 62°. 

6. Trace a concentric circle around from the intersection point to the vertical north axis, on which is displayed the altitude angles. 

7. Interpolate between the concentric circle lines to find the altitude. In this case the intersection point sits exactly on the 30° line. 

8. This gives the position of the sun, fully defined as an azimuth and altitude.

Battery Management System

A battery management system (BMS) is an electronic system that controls the charging and discharging of a rechargeable battery (cell or battery pack) by protecting the battery from operating outside its safe operating area monitoring its state, calculating secondary data, reporting that data, controlling its environment, and balancing it.

Basic Features of BMS:

Overcharge Protection: Protects the cells as well as the battery from overcharding beyond its safe limit.

Deep Discharge Protection: Protects the cells as well as the battery from deep discharding while powering a load.

Cell Balancing: When a cell is fully charged bypass that cell to let the other cells to be charged.

Types of BMS depend upon the type of cells as well as the number of cells in series. As per the number of cells in series, BMS is classified as

1S: Only one cell

2S: 2 number cells in series

3S: 3 number cells in series

and so on...

The voltage of BMS depends upon the cell type like for Li-Ion 1S BMS its rated voltage is 3.7V. For 2S it would be 7.4V. On the other hand for lithium ferro-phosphate cell (LiFePO4), 1S BMS would be 3.2V and 2S would be 6.4V, and so on...

 Every BMS has it's terminal marked connection needs to be done as per marking. 

 

 

For this lithium ferro-phosphate 1S BMS
B- Terminal is for Battery Negative
B+ Terminal is for Battery Positive
P+ is for Power Positive
P- is for Power Negative 

B+ and B- connects with the battery and P+ and P- go to the load or charger.

For the above Round type Li-Ion BMS also B+ and B- connects with the battery and P+ and P- go to the load or charger.

 This lithium ferro-phosphate 2S BMS has five terminals apart from B+, B-,  P+, P- it has one extra terminal that is BM. This BM terminal goes to the middle terminal of the battery series.

 The Li-Ion 2S BMS also has the same pin configuration.

 For 3S Li-Ion BMS, the Connection diagram is shown above. The lithium ferro-phosphate does not come with a 3S configuration.

Instead lithium ferro-phosphate BMS comes with 4S configuration. The connection diagram is shown.

Surge Protection Device

A voltage spike is a transient event, typically lasting 1 to 30 microseconds, that may reach over 1,000 volts. Lightning that hits a power line can give a spike of over 100,000 volts and can burn through wiring insulation and cause fires, but even modest spikes can destroy a wide variety of electronic devices, computers, battery chargers, modems and TVs etc, that happen to be plugged in at the time. However, lightning and utility power anomalies only account for 20% of transient surges. The remaining 80% of surge activity is produced internally. Although these surges may be smaller in magnitude, they occur more frequently and with continuous exposure can degrade sensitive electronic equipment within the facility.

A Surge Protector or a spike suppressor, surge suppressor, surge diverter, Surge Protection Device (SPD) or transient voltage surge suppressor (TVSS) is an appliance or device intended to protect electrical devices from voltage spikes in alternating current (AC) circuits. 

Typically the surge device will trigger at a set voltage, around 3 to 4 times the mains voltage, and divert the current to earth. Some devices may absorb the spike and release it as heat. They are generally rated according to the amount of energy in joules they can absorb.

There are three types of power surge protectors:

• Type I: This Power surge protector is installed at the origin such as the main distribution board.

• Type II: It is installed sub-distribution boards.

• Type III: This power surge protector is installed at the protection load.

Reference:
[1] https://en.wikipedia.org/wiki/Surge_protector
[2] https://new.abb.com/low-voltage/products/surge-protective-devices
[3] https://www.se.com/in/en/product-subcategory/1615-acti-9-surge-protection-devices-spds/

How to make Pulse Oximeter at Home

In our previous blog, we interfaced Pulse-Oximeter (Max30100) Module to NodeMCU. With a little bit of modification that can be upgraded to a full functioning Pulse-Oximeter. We have interfaced 0.96" I2C OLED display before. Today we made a Pulse-Oximeter using that knowledge.

Follow our previous blogs for a better understanding of the scenario.
Pulse Oximeter MAX30100 Interface with NodeMCU
OLED Display Interface with Arduino

Things we need:

• NodeMCU
• Max30100 Module
• 0.96" OLED I2C Display Module 
• Female Berg Strip Connector
• Dot Vero Board
• Soldering Kit
• Nut and Bolts 1/8"
• PVC Spacer Tube

Connection Diagram:
Now follow the diagram below to do the connections.

After the connection is done upload the code below.

Source Code:

Video:
Watch the video for a better understanding.

Reference:

[1] Sarkar, S., Ghosh, A., Chakraborty, M., & Mondal, A. (2024). Design, Hardware Implementation of a Domestic Pulse Oximeter Using IOT for COVID – 19 Patient. International Journal of Microsystems and Iot, 2(1), 469–475. https://doi.org/10.5281/zenodo.10629635

Nokia 5110 LCD Display interface with Arduino

This LCD device is mainly used in Arduino but it can be connected with any 3.3V controller. These LCDs are used in Nokia 3110/5110 cell phones. It is a very cheap monochrome LCD module made of 84 x 48 pixels. It can be used to display graphics and text together. This display is based on the PCD8544 driver.

Pin configuration of this device is almost like the 16x2 LCD module only instead of 8 data pins one serial data in (Din) pin and one clock (Clk) are there. The list of the pins and their description are listed below.

RST: Pin type active low, so 0V Resets the LCD

CE: Cheap Enable is used to enable the device before sending anything to the LCD

DC: Data/Command is used to select between Rata Register or Command Register

DIN: Data In is used to send information serially to the display. It could be Data or Command

CLK: Clock is used to synchronize the display with the controller

VCC: To power, the pin 5V or 3.3V is applied here

BL: This pin is used to power the Backlight of the display

GND: This is used to ground the device.

Things we need

• Nokia 5110 Display
• Arduino
• Resistors
  1. 1k Ohms x 5 Nos.
  2. 330 Ohms / Potentiometer 1k
• Jumper Wires
• Bread Board

Connection Diagram:

pin 7 - Clock (CLK) pin 6 - Data In (DIN) pin 5 - Data/Command select (D/C) pin 4 - Chip Enable/select (CE/CS) pin 3 - Reset (RST)

Before you upload the code library needs to be installed. Please follow the below mention instruction to install the library.

https://creativestudio1973.blogspot.com/2019/11/introduction-to-arduino-library-manager.html

In the code below we have displayed text, then we have displayed the same text in inverted mode, after that we have rotated the text finally we displayed the ASCII table.
Source Code 1:

Video 1:

Here in the second code, we tested display by displaying an image. To display the image we have to convert the image into code. To do that open the link image2cpp. 
Link: http://javl.github.io/image2cpp/

Go to "Choose Files" and select the file from your computer.

Select the "Canvas Size" to 84x48 and "Scaling" as Scale to fit. Then check the preview to make sure everything is alright.

Now select the "Code Output Format" to "Arduino code" and click on "Generate code"

Finally copy the code and add that to the code below to display an image of your own.

Source Code 2:

Video 2:

Pulse Oximeter MAX30100 Interface with NodeMCU

The MAX30100 has integrated pulse oximetry and heart-rate monitor sensor integrated circuit with I2C interface. NodeMCU is mostly preferred as it is a 3.3V controller.

Components Required:

• Pulse Oximeter MAX30100
• NodeMCU
• Jumper Wires
• Bread Board
• Soldering Kit (Optional)

Before the connection is done there is slight modification needs to be done. The board shown above has little issue with NodeMCU or any other controller. As the NodeMCU is a 3.3V controller it sends or receives I2C signals at a 3.3V logic level. MAX30100 usually comes with its I2C bus pulled up to 1.8V. This is why if you don't make any modifications, the code might not run. Although without modification, you would be able to check its I2C address but rest of the functions won't work.

Now before we go for the modification let's see the Pinout of MAX30100. It has 14 pins. The I2C bus is at Pin 2 and Pin 3 is SCL and SDA. Pin 13 is for INT (Interrupt), Pin 11 and 12 is for Power and Ground.

If we look at the module we will be able to find that Pin 2(SCL), Pin 3(SDA), Pin 5(IR_DRV), Pin 6(R_DRV), Pin 13(INT) are connected to the header. Pin 9(R_LED+) and Pin 10(IR_LED+) are connected to 3.3V. Pin 11(VDD) is connected to 1.8V. Pin12(GND), Pin4(PGND) are connected to the ground. 

Above the red marked 3 pin device is a 1.8V regulator supplying 1.8V to VDD (Pin 11) and also to the three 4.7k Ohms pull-up resistors.

Here we have three 4.7k Ohm resistor pulling up Pin 2(SCL), Pin 3(SDA), Pin 13(INT) up to 1.8V. Here we have to make a change and we have to pull these pins up to 3.3V to connect them with NodeMCU. This could be done in two ways.

Option 1: Remove them and connect 3 external 4.7k Pull up Resistors for 3.3V.

Option 2: Without removing them we will use them by making a slight change in the module. To do that at first with a help of a sharp cutter we will disconnect them from the 1.8V pin of the regulator. Just make a cut at the Red marked position shown in the image below. To make sure the disconnection is complete check continuity using a Multimeter. Do it carefully so that no damage happens at any other part of the device.

Then Connect the points shown below. Make sure during soldering no other points get connected.

If the above step is difficult for you then you can connect these two. Both the pins are 3.3V so they won't make any difference.

For me the first option was easier so after mofification my module looks like this.

Connection Diagram:

Now connect the pins accordingly.

• VIN to nodeMCU 3.3V Pin
• SCL to nodeMCU D1 Pin
• SDA to nodeMCU D2 Pin
• INT to nodeMCU D0 Pin
• GND to nodeMCU GND Pin

Before you upload the code library needs to be installed. Please follow the below mention instruction to install the library.
https://creativestudio1973.blogspot.com/2019/11/introduction-to-arduino-library-manager.html

Source Code:

Video:

Datasheet:

https://datasheets.maximintegrated.com/en/ds/MAX30100.pdf

Reference:
[1] Sarkar, S., Ghosh, A., Chakraborty, M., & Mondal, A. (2024). Design, Hardware Implementation of a Domestic Pulse Oximeter Using IOT for COVID – 19 Patient. International Journal of Microsystems and Iot, 2(1), 469–475. https://doi.org/10.5281/zenodo.10629635

Light Sensor BH1750 Interface with Arduino

Light Intensity is an important parameter. This could be measured by various components (eg. LDR) with proper calibration. This is why BH1750 is easy to use. It has an I2C interface so data could be extracted easily using the I2C Bus.

Things we need:

• BH1750
• Arduino
• Jumper Wires
• Bread Board (Optional)

Connection Diagram:

Connection is very simple, BH1750 has five pins Vcc, Gnd, SCL, SDA, Addr. Connect the pins accordingly.

• VCC pin to Arduino 5V
• GND pin to Arduino Ground
• SCL pin to Arduino A5
• SDA pin to Arduino A4

Once the connection is done open Arduino IDE and upload the code below.

Before you upload the code library needs to be installed. Please follow the below mention instruction to install the library.
https://creativestudio1973.blogspot.com/2019/11/introduction-to-arduino-library-manager.html

Source Code:

Video: