File System for the RC

[chris31]

The link isnt working do to an extra ")" at the end of the link. If you got to http://www.ladyada.net/make/minty/ it works.

[JimGRobot]

Originally Posted by EHaskins

Did you get the SPI working or are you just using an rs232-TTL converter?

My testing has been solely with the SPI port. I built an RS-232 to SPI bridge using an SX-48 microcontroller development board that echos input from the serial port out to the SPI port, and the reverse as well.

Doing this makes for some funky operation from the terminal, but it really boils down to typing an extra space character to get the DOS prompt back from the module. It ignores the extra spaces, so no harm done... I also wrote some testing code that talks SPI directly to the thing.

I have some more information and a link to the test program here, http://www.techranch.com/blog/, and will be posting more info soon...

One thing about SPI on the RC. There is a built-in SPI port on the PIC chip, but I think it is used to talk to the master processor. The test code I wrote just bit-twiddles some port pins to generate the clock signals. SPI can use as few as 3 pins, but this one uses 5; data out, data in, clock, chip select, and busy. There are 2 others available, data direction and reset. I am currently resetting the chip from a port pin, but I doubt that I really need to do this. The data direction signal would make communication with the module more predictable, but I probably won't use it.

I will be posting some more sample code on the blog...

I hope this helps.

Thanks,
Jim

[Mike Copioli]

Hey guys, it sounds like you are trying to do exactly what we did last year with Chicken AID. The only difference is we used a USB thumb or an SD card. We used a development board that we created to prototype Chicken AID. The Board uses SPI to communicate to the SD and USB host. We use USART to communicate to the R/C the board has a built in RS232 converter.
Here is the link http://www.crosstheroadelectronics.com/uPICFAT.htm
The development system is around $150. But it is a complete, out of the box solution. It includes the board, the plug in with examples, it also comes with a power supply, LCD and serial cable.

Mike Copioli
CTRE

[EHaskins]

Can you post the code you have finished?

[JimGRobot]

You can read more about my work here:

http://www.techranch.com/blog/

And you can download my current test file from here:

http://www.techranch.com/Files/SPI_Test.c

[JimGRobot]

Originally Posted by Bharat Nain

If you don't mind, what are it's annoying qualities and good ones?

The good qualities in general are its low cost and basic ease to use. I think it is very cool that we can drop a file system on the RC to make autonomous ops better.

The annoying qualities are that it runs on 3.3 VDC instead of 5 VDC, and that the commands must be lower case and the file names must be upper case, etc. One catch using the SPI interface is that you have to send meaningless bytes to have it send data back to you, but that is the case with any SPI device.

Access to file data is very primitive, and I haven't had time to write some higher level code for accessing the data, but considering the simple task we have of simply reading from a file, it should work OK.

I have some more information here, http://www.techranch.com/blog/, and will be posting more...

Thanks,
Jim