<< return to Pixycam.com

pixy flash memory usage

Pixy Hardware
#1

I was searching the forum about capturing pixel values and sending them over UART interface to a board.

the issues i saw;

  1. UART interface is slow to send real time images.
  2. the RAM is not enough to keep 640x400 images.

However, is there a way to save an image to flash memory (1 Mbyte) for sending it afterwards?
Speed will not be a problem in this application.

Thank you,

#2

Hello Necmi,
Good question! Flash devices tend to be much slower for writing. But is it fast enough? Pixy’s flash takes about 1us per byte (writing), so, for even a 320x200 frame, it would take 64ms, which is too slow. Ideally, you’d want it to take about 200ns or faster.

Edward

#3

Thank you very much for your answer.

According to the calculation, 640x400 frame will take 128 milliseconds. This time delay is not a problem for my application.The basic application is saving 640x400 frame into flash memory and send it through UART interface.

I am new to the Pixy applications; therefore, I made my choice after seeing RAM capacity (264 KBytes). It is unfortunate that we cannot use it.

Necmi

#4

Hello Necmi,
Pixy executes most of its code out of RAM because it is much faster (0 wait-state). The 264K of RAM is there and you can do what you want with it, but there are some trade-offs.

Can you describe your application? Maybe we can help you find a solution.

Edward

#5

Hello again,

It is a simple application. I want to save a single frame with 640x400 resolution, and send it to a microcontroller by UART interface. UART is my only choice.

Therefore, I need to save it to flash memory to send it afterwards or send it over RAM memory. I am open for suggestions.

Necmi

#6

Hello Necmi,
I can’t think of a straightforward way to do this with Pixy. (sorry)

What is on the other end of the UART? Does it have enough memory? That is usually the problem, which is one of the reasons we haven’t added this kind of functionality. Perhaps if you could explain your application. What do you plan on doing with a raw frame?

Edward

#7

Hello again,

Pixy is connected to an onboard computer by UART interface. This onboard computer is designed in university; therefore, it has enough memory to keep several images easily. The image transfer can take long time, this is not a problem. The camera will work in a dark environment. If the raw image data has enough values indicating a light source is present, this image will be saved in the onboard computer memory.

I have two requirements;

  1. Using UART interface
  2. 640x400 resolution

Thank you for your all answers.

Necmi

#8

Hello Necmi,
Thank you for the description. I feel like I understand your application better now.

I’ll log your requirements as a feature request. I’m not sure when it will get implemented, but we’re always open to new ideas.

thanks!

Edward