Advanced Communication Methods for Pixy2

Pixy2 is pretty versatile when it comes to connecting through different interfaces.
It can communicate via serial methods like SPI, I2C, and UART, or you can also use USB—though there are some limitations if you want to go the analog digital route.
If you’re opting for USB, just remember that it usually needs an operating system to work, and you’ll want to use the libpixy2 library, much like what you’d do with a Raspberry Pi or BeagleBone Black.
And just a heads up: among all these options, USB is your go-to for the fastest communication speed!.

When it comes to speedy communication, USB really takes the crown as the fastest option out there.
If you’re using Pixy2 with an Arduino, SPI follows closely behind, reaching speeds of up to 2 MHz.
Now, if you’re working with another microcontroller that doesn’t support USB, don’t fret! SPI is still your go-to for that high-speed vibe.
On the other hand, UART offers decent speeds ranging from 19,200 bps to 125,000 bps.
And if you’re looking for flexibility, I2C might be the better choice for connections.
Just remember, since UART and I2C speed levels are pretty similar, it all boils down to your specific needs in each scenario..

Setting up the Piximon interface is super easy! First, just click on the gear icon to get started.
Then, dive into the Piximon document and locate the interface tab; this is where you’ll find all the juicy details on how data is outputted, covering everything from Arduino and ICPI to SPI and I2C.
Oh, and even though the Lego I2C is mentioned, we won’t go into that here.
On the back of the Pixy, you’ll spot a pin header with an RX pin and an SPI pin that work as Master In and Slave Out pins.
Plus, there’s a pin for 5V input or output—pin 3 is your SPI clock pin, and pin 4 is for SPI Master Out Slave In.
Easy peasy!.

Alright, let’s break down the pin definitions for UART and I2C.
So, the UART interface has a TX pin, which is super important for transmitting data.
Over on pin 5, you’ve got the I2C clock pin, which helps keep everything in sync.
Don’t overlook pin 6, and just for your reference, pin 7 is set aside as the SPI slave select pin.
For I2C, pin 9 is your data pin, called SDA, and you can power pin 10 with anywhere from 6 to 10 volts.
If you’re looking to control a servo motor via the SPI protocol, make sure to use pins 1, 3, and 4 for communication..

When it comes to SPI communication, there’s usually a slave select pin involved.
In this case, it’s hooked straight to the Arduino, making things super easy to connect.
What’s cool about this setup is that it actually uses that slave select pin , giving you a little more control while chatting with other SPIs.
Plus, you’ll want to remember that this setup uses four pins instead of the usual three, specifically pins one, three, four, and seven.
So, it’s pretty straightforward and opens up more options for managing your SPI communication..

Alright, let’s dive into I²C and UART connections! When you’re working with I²C, all you really need are just two pins: SDA and SCL, which are specifically pins five and nine on your setup.
If you’re looking to connect multiple devices, you can set a specific address to hook up up to 127 devices , but just a heads-up – if you’re using a Pixy2, it has a fixed address that limits you to just one.
Now, when it comes to the UART interface, you’ll need another pair of pins: TX and RX, which are pins one and four.
Plus, don’t forget you can play around with the baud rate by tweaking the settings in the configuration window!.

So, let’s talk about how the Pixy2 handles its analog outputs! It gives you these cool analog digital X and analog digital Y readings, which show the coordinates for the biggest object it recognizes.
But here’s the catch: it only has one analog output pin, which is pin 8.
This means you can only monitor one coordinate at a time.
To keep things organized, pin one is there to let you know if it successfully recognized something or not, and the voltage you’re dealing with ranges from 0 to 3.3V.
This voltage acts like an analog input to figure out the size of the coordinates.
Just keep in mind, since there’s only that one analog output pin, you’ll need to choose whether you want to track X or Y in the settings..

Alright, let’s break down how the system operates regarding coordinates and protocols.
First off, it gives you the X and Y coordinates of the biggest object that Pixy2 picks up.
If you see a high pin one, it means it’s recognized; a low pin means it missed it.
Now, when the voltage hits 0 V, X is all the way to the left, and at 3.3 V, it slides to the right.
The same goes for Y : 0 V is at the bottom, and 3.3 V takes it to the top.
Moving on to serial protocols like SPI, I2C, and UART, they each have their own ways of communicating, but their protocols are quite similar.
Typically, the packet structure has two fixed headers and a response with some slight variations, including hex values like AE and AF.
Lastly, don’t forget about that checksum, which is a 16-bit value coming right after the data length and is the total of all the data bytes that follow..

Let’s dive into how version requests and responses work! A version request kicks off with a hex value, either A2 or C1, and then it has a version request type of 14, which is actually 2 in hexadecimal.
Since there’s no additional data, the data length is zero.
When the response rolls in, it appears as AFC1, with a response type of 15 (which is F in hexadecimal) and a data length of 16 (that’s 10 in hexadecimal).
Don’t forget about the checksum—it’s a 16-bit value that’s crucial for making sure your data is valid, so double-check it before you proceed.
The first two bytes? They reveal the hardware version.
The next pair shows the firmware version, while the remaining bytes break down the firmware details in ASCII.
Stick around for the next session where I’ll explain the protocol in more detail and dive into serial communication!.