AT89C52 interface SD Memory Card

Dear Fren,

I will try to make it work. If the thing is work i will let you know.

Ya, may i know how to drive the data from C52 to MMC/SD? The MMC/SD bus signal max voltage is only 3.6V.

Thank you.

use voltage divider for data & control lines

Dear Fren,

I'm using transister to drive the data and control line. It work OK.

Now the testing board is working OK. May i know what's the next step to do the FAT system?

Please advice...
Thank you.

sending/receiving data both ok?

i mean sector reading/writing. well try to analyse the FAT code u downloaded from chan's website. you might need more ram i guess.

Dear Fren,

Yup, sending and receiving data to sector are ok.

If using chan's FAT code just need 1kRAM. I already wire up external ram for my testing board.

I have download the coding but don't know how to start. Please can you guide me?

Thank you,..

sure.. i have downloaded the code, rev 0.06

I need to check the code for its interfacing.. you may need RTC too.. but let me check

Dear Fren,

Thank you very much,..

Ya, the latest version is 0.06. If we need RTC on testing, is ok..I will ready for that. On the coding part i just add in some the basic part in diskio.c. I have ready fren...

Dear Fren,

May i know what's the status now? I still waiting your reply.

Thank you.

Sorry my PC got crashed i got it installed fully yest. I just looked at main.c file of AVR code, and in that code, chan has shown the complete usage and i think we just need to test this FAT module isn't it?

so we will first try with reading directory entry from root itself. here is one case i got from main file. We just need to find out what minimum needed for this FATFS to work.

case 'l' :	/* fl [<path>
] - Directory listing */
	res = f_opendir(&dir, ptr);
	if (res) { put_rc(res); break; }
	p1 = s1 = s2 = 0;
	for(;;) {
		res = f_readdir(&dir, &finfo);
		if ((res != FR_OK) || !finfo.fname[0]) break;
		if (finfo.fattrib & AM_DIR) {
			s2++;
		} else {
			s1++; p1 += finfo.fsize;
		}
		xprintf(PSTR("%c%c%c%c%c %u/%02u/%02u %02u:%02u %9lu  %s\n"), 
					(finfo.fattrib & AM_DIR) ? 'D' : '-',
					(finfo.fattrib & AM_RDO) ? 'R' : '-',
					(finfo.fattrib & AM_HID) ? 'H' : '-',
					(finfo.fattrib & AM_SYS) ? 'S' : '-',
					(finfo.fattrib & AM_ARC) ? 'A' : '-',
					(finfo.fdate >
>
 9) + 1980, (finfo.fdate >
>
 5) & 15, finfo.fdate & 31,
					(finfo.ftime >
>
 11), (finfo.ftime >
>
 5) & 63,
					finfo.fsize, &(finfo.fname[0]));
	}
	xprintf(PSTR("%4u File(s),%10lu bytes total\n%4u Dir(s)"), s1, p1, s2);
	if (f_getfree(ptr, &p1, &fs) == FR_OK)
		xprintf(PSTR(", %10luK bytes free\n"), p1 * fs->
csize / 2);
	break;

I think we also need to edit mmc.c driver file according to your code keeping the same name of functions. So check that file carefully. I think your first step to FATFS is this only, get your mmc code work with chan's library.

Dear Fren,

Hope your there everything is fine.
Thank for your guid line..but i still very blur when study the code...still don't know where to start and do the testing. The coding look very complicated and theirs mmc code very much difference then us .

Thank you,.