S12 / MagniV Microcontrollers中的主题 Re: S12XDP512 File System SDCard

S12XDP512 File System SDCard

vbelloir — Mon, 03 Mar 2008 17:38:30 GMT

Dear guys,

I'm new in the forum, so let me introduce myself.
I m an hardware ingineer in a french company.
I'm not famillar with S12X micro controller. I 'm used to design with ARM9 processor.
For A customer, I must use a S12XDP512 proc. The customer wants to interface a flash memory like SDcard, and store some log datas on it. He also wants the data to be easily red in a Windows system.

In my opinion, the SD memory can be interfaced with the S12X with the SPI bus. It want be a problem I think. But I don't know how to organize the datas in the SD card. Doesn't somebody has already used a file system like FAT (or another file system readable by Windows) with a S12X. I'm afraid that FAT will be to large for the MCU flash memory!!

Thanks a lot for your help.

Vincent

Re: S12XDP512 File System SDCard

JimDon — Mon, 03 Mar 2008 22:44:38 GMT

- You will have to use Fat.
- It can be done in 2K-4K.
- It is not an easy job, so I recommend this chip instead.

You can get the chip qty 1 for about 12.00.

Re: S12XDP512 File System SDCard

vbelloir — Tue, 04 Mar 2008 00:24:38 GMT

Ok, it seems to be interrested.
If I well understand the DOSonChip already has a FAT?
This is the DOSonChip onboard chip (CD17B10) which organizes the datas and file with FAT?

It could be a good solution, but does someone has already tried to implements FAT in an OSless code?

Message Edited by vbelloir on 2008-03-03 04:52 PM

Re: S12XDP512 File System SDCard

JimDon — Tue, 04 Mar 2008 00:52:38 GMT

Correct, both fat16 & fat32.
You talk to the chip via rs-232 or SPI and just send open, read and write commands..
You can just buy the chip and put it on your board for production.

Re: S12XDP512 File System SDCard

vbelloir — Tue, 04 Mar 2008 00:55:28 GMT

Sorry Jim, I was editing my post when your sent your new one.
Your solution seems to be good, but I still want to know if I can found a FAT file system for OSLess software.

Re: S12XDP512 File System SDCard

JimDon — Tue, 04 Mar 2008 01:21:00 GMT

How much are you willing to spend?

If you do it yourself, you it will cost way more of your time (and money) than to just buy it.
The problem with a file system is testing it. It sounds easy enough but it is not.
Just because you write a few files and read them on you PC does not mean problems won't
come up later.
Whats more, there are several different kinds of SD cards, that need support and testing.
Even the size of the card matters.
Then you will need to optimize it as running a file system with out sector buffers the size of the the flash sectors (32K) means it is slow, very slow unless you tweak the heck out it.
Trust me, I've done it.

If you are asking if there is a free, well tested, reliable one then the answer is no.

The reason why is if you went through the trouble to do this, you would not want to give it away. Plus there is never ending support issues.

You can buy code, but in the end you will find that the dosonchip is a good way to go. No memory used, no code to port, if you change micros no problems.

Here is one you can buy, read the site it is just the first one I stumbled upon, I am sure the are many more.
http://www.blunkmicro.com/fat.htm

Re: S12XDP512 File System SDCard

vbelloir — Tue, 04 Mar 2008 01:28:01 GMT

I found the Blunk Fat port.
I agree with you when you say that a file system is very difficult to develop and to test.
I won't try to develop it by myself, this is not my job and I don't think I will be able to do that.
I'm just looking for all the solution I can find (free or not) that can fit my needs : write datas on a SDcard, that can be readable by Windows.

Thanks you for your help. I really appreciate.

I agree with you when you said that the Dosonchip is probably the good solution.

Vincent

Re: S12XDP512 File System SDCard

peg — Tue, 04 Mar 2008 05:05:52 GMT

Hello Vincent,

You could take a look at this.

I don't know anything about it other than it exists here.