Choosing Microcontrollers

ThanhDan · Joined: 07 Jun 2022 Posts: 19

Hi I'm choosing a microcontroller for my line following robot project. The robot is basically a small AGV that can carry a 2kg colored package. I need a color sensor to identify the color of the package and a camera to track the line. Based on the above requirements, how do I choose my microcontroller (i.e the sensors feed this much data back in 1 sec and the MCU has this much memory therefore it can handle the data sent back to it...)

temtronic · Posted: Tue Oct 11, 2022 5:24 am

Something like an analog RGB sensor to detect colour would need 3 analog inputs ( R,G,B ). You could use an RGB LED in 'reverse' though it'll take so bench time to get it to work,BTDT prePIC.....sigh that was a LONG time ago....

Providing that the colour 'tags' or boxes are the same distance from the vehicle, you only need to run the 'calibration function' once.

I'm sure there's probably some real fancy 'colour detectors' out there today, even using say a digicamera as the 'input', but as a 'home project' keeping it simple is best.

Ttelmah · Joined: 11 Mar 2010 Posts: 19219

A 'camera', sounds a very complicated way of doing a line follower.
Normally these are done by a linear array sensor. Much easier to interface
and much simpler code.
If you do want to use a camera, you probably quadruple the amount of
storage space needed in the chip, and may well find it very difficult to
interface to a PIC.

temtronic · Posted: Tue Oct 11, 2022 9:09 am

I 'think' he just wants the camera to detect the coloured boxes. If so, dead simple as you can buy a RGB module for <$10 ! I2C interface,so just 2 wires !

Ttelmah · Joined: 11 Mar 2010 Posts: 19219

He says: "and a camera to track the line."....

PrinceNai · Joined: 31 Oct 2016 Posts: 452 Location: Montenegro

PIXY2 camera: https://pixycam.com/pixy2/

I have one, but I never tried to interface it with a PIC. They do offer the code for Arduino and Pi.

Ttelmah · Joined: 11 Mar 2010 Posts: 19219

That is nice, since you are not dealing with the image. Problem is, even for
very small images, the PIC in general does not have the memory to cope
with images. With that you program the camera to actually do the line
detection.

temtronic · Posted: Wed Oct 12, 2022 5:04 am

Do you HAVE to use a camera as the white line sensor ? It's tremendously far more complicated both in hardware and software to be used as a 'white line sensor (wls)' !

One of the simplest wls is a single LED and 2 photo detectors. Only requires 2 analog pins and some simple ADC code. You read the sensors and determine where the white line is. Once properly calibrated, the PIC will be able to follow the line very,very well. You could think of it as a 3 pixel wide 'camera'.

Using a real 'camera', especially any RGB (colour input) requires a LOT of code ,probably beyond the abilities of 99.44% of the current PICs.
If, IF, you can find a camera module that has 'zone' programming, can be turned into a B&W camera, then it 'may' be possible to have a PIC see the white line. Far too complicated when an EASY 'off the shelf' wls is available.

Can it be done, yes... should it be done, no. Unless you have 1-2 years to devote to this one task.

newguy · Joined: 24 Jun 2004 Posts: 1902

Pretty sure this is a school assignment Jay. This bit:

PrinceNai · Joined: 31 Oct 2016 Posts: 452 Location: Montenegro

Still an interesting topic, maybe not for the OP, but for the others.

Most likely it is a school assignment, as Newguy said. If the sensors are fixed (meaning they are provided by the school), they also must have a box of PIC's somewhere that are able to do the job at hand. It is just too hard to find anything that is readily buyable these days (that also fits your needs and one can get in a reasonable time) for the school not to provide those too. If that is the case, that PIC's are already there, it is a non-question. Just grab the fastest and biggest memory wise you can get. Possibly supported by the old MPLAB. Because in that case only your programming will frustrate you, not the environment on top of that.

BTW, as every year in this time, things are slow at work. So I had time to think about the sensors. The one from an optical mouse? For a line follower?

ThanhDan · Joined: 07 Jun 2022 Posts: 19

ThanhDan · Joined: 07 Jun 2022 Posts: 19

ThanhDan · Joined: 07 Jun 2022 Posts: 19

ThanhDan · Joined: 07 Jun 2022 Posts: 19

Ttelmah · Joined: 11 Mar 2010 Posts: 19219

Think about it. Even a tiny picture will be perhaps 192*128 pixels. Even
in B&W, one byte per pixel. Needs then 24576 bytes to hold just a single
frame. The 877 has 192 bytes.....

Even if you have no different grey scales, just a single pixel on/off, a frame
still needs 3072 bytes. Sixteen times what the chip has.