Reading sensor values via I2C on Arduino

First up, you’ll want to check out the PM2008 datasheet and take a close look at the I2C section.
There are mainly two ways to work with I2C: sending commands and reading data, but for our needs, we’re all about that data reading.
So, start by sending a command, and then you can dive into reading the data.
Don’t forget, the PM2008 has a specific address you need, which is 0x28 in hexadecimal for grabbing 32 bytes.
Just a heads-up: when it comes to sending commands, you might actually use 0x50 instead of 0x28..

Understanding I2C addressing can be a bit tricky, especially since data sheets can be a mixed bag of explanations.
For example, when you take the hexadecimal value 0x50 and convert it to binary, it shows up in a specific format that may differ from one sheet to another.
If you drop the last digit from that binary value, you end up with 28.
Now, here’s a crucial point: the I2C address uses just 7 bits.
This means that in a one-byte format, the first seven bits represent the address, while the final bit is used to indicate whether you’re writing or reading.
So, when you’re writing values to an I2C slave—like a sensor or another electronic component—you simply add a 0 after the address to signal that it’s a write operation..

When it comes to I2C, doing a read operation is as simple as adding a 1 to your value, which in our example bumps 50 up to 51.
If you’re using Arduino, the good news is that it automatically adds that 0 or 1 for you, which means less hassle—just double-check the address in your data sheets.
The address you’re working with follows the I2C standard , sitting at 7 bits and showing up as 0x28, while the command addresses are 0x50 and 0x51, creating a little confusion.
Keep in mind that different sensor manufacturers might mix things up with their protocol formats, so it’s crucial to send and receive your data according to their specific guidelines.
Lastly, don’t forget about the checksum! You’ll be performing an XOR operation from the first byte onward, and make sure to set up your macro constants for the address and STX early on in your coding journey..

So, first off, you really need to allocate a buffer—that’s super important for keeping things running smoothly.
Once you’ve got that set up, you can dive into the code to get the wire initialized by starting with serial.begin(9600) .
For the best performance, it’s a smart move to handle your hardware control code before the serial code, just to get all your setups sorted first.
You’ll want to read those sensor values every three seconds using a separate function, especially when handling wire requests from address 32.
And don’t forget, when you’re reading, you’re gonna need to shift one bit back and add a 1 to nail that hex value of 51 , so make sure you use the right Arduino commands for it..

Let’s take a closer look at serial communication! First off, the wire we use is quite similar to what you’d find with TB wire, and when inserting, it’s essential to place it correctly.
Now, keep an eye on that IDX buffer; once it hits 32, you’re out! This means it can gather data until it breaks out, but watch out—sometimes it can exit early if it detects any false data.
Also, checking for STX, which is the start of text, and CS for checksum is super important.
If there’s any hiccup in following these protocols, the whole process just halts.
Lastly, the TCS, or temporary checksum, gets its value from buffer 0, and we kick off TI, or temporary index, at zero..

Let’s dive into the calculation process! It kicks off by taking a random value and subtracting 2 , and then we’ll subtract 1 from that result, which eventually leads us to 31 .
After that, we execute an XOR operation from i all the way up to 30 , and just like that, the last bit becomes 31 .
If things don’t match up with Csperl-AMD1, it’s crucial to grasp what that means.
Plus, nailing a successful checksum operation is key for keeping our data safe, which is usually confirmed with an OK message from the system..

So, once we finish parsing everything successfully, the first thing we do is kick off the wire and serial.
We’ll be calling the read function every 3 seconds to snag 32 bytes of data.
While that’s happening, the wire keeps on looping as long as the data looks good, and it’ll only stop when our buffer hits 30.
If we find the ID buffer isn’t quite right or if the checksum doesn’t match up, that’s our cue to pack it up and exit.
If all goes well, we can dive into parsing the data one byte at a time, but honestly, we can skip the nitty-gritty details here and just check the datasheet for that info..

In this session, we’re diving into how to read PM2008 sensor data using I2C communication.
This is super important for various sensors and actuators, especially when you can’t find the right Arduino libraries.
While it’s not too tough, it’s really important to check out the data sheet carefully.
That’s because different sensors can have different protocols and checksum methods that might impact how they communicate.
Once you get the hang of these nuances, you’ll find that you can do direct I2C communication without too many hiccups..