Sunday, May 3, 2009

Surveyor SRV1 Camera

At work, we purchased 2 SRV1 Blackfin Surveyor camera boards for $200 each.

Basically small cameras attached to a powerful processing board. The Blackfin board is designed as a robot controller with built in image processing. In addition to PWM drivers, I think the default firmware does edge detection, blob tracking and centroid.

The documentation is sparse. The setup assumes that you bought the wireless radio, and robot body. But the users forum is great. Friendly folks of different experience levels. And the Administrator/Company owner asnwers tech support at night, same day!
No quibbles there!

Actually, it is supposed to work right out of the box: there is a java console to talk to the camera and transfer images (very slowly).

Well, mine didn't.
I needed to setup a serial connection for initial communication. I didn't have a 3.3V power supply (SRV1 is 3.3V processor).
What I had was
Sparkfun RS232 shifter (RS 232 to TTL, you supply the voltage)
Sparkfun FDTI Usb-RS232 with 3.3V output.

First thought was connect the FDTI Usb-RS232 to RS232 shifter to SRV1, and use 3.3V from FDTI to power the RS232 shifter and SRV1.

Okay, that didn't work. I figured I had screwed up the TX-RX pins somewhere amongst the multiple chips.

Second thought was connect the RS232 shifter to SRV1 (plain jane serial connection) and use the 3.3V from FDTI to power the RS232 shifter and SRV1.
That didn't work either. There are 3 LEDs on the SRV1:
LED 1 (yellow) RX
LED 2 (yellow) TX
LED 3 (red) Power
Boot sequence should be all three, then just 2 and 3.
Only power came on. Quick check showed that the supply voltage dropped to 2.9V
The FTDI Usb-RS232 3.3V couldn't supply enough current.

Well, I thought that I read you could pick off the unregulated battery supply to power it.
I had a 5V powered breadboard, so I tried that.
Oh, wow, all 3 LEDs, then just 2 and 3!
I connected using SRV1 java console, and I got an image! wait, that isn't right?
The image was mostly covered in black/green/pink rows.

I assumed that there was a connection problem in my circuit, so I chewed on that for a while. Finally I signed up for the Users Forum and asked for help.
First question: Are you using 3.3V?

Ug, so I borrowed a variable power supply and dialed in 3.3V. A perfect picture appeared!
Apparently, the blackfin won't boot with less than 3.0V AND the camera gets noisy (green rows) at more than 4.0V.

So now I can begin trying to get the camera system to do real work!

No comments:

Post a Comment