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exodia505
Joined: 07 Feb 2012
Posts: 34
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| MMC Card |
 Posted: Thu Feb 16, 2012 3:03 pm |
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Hello!!
I want to use MMC for simple application , who can give me an example?
Is MMC driver available in ccs ?
I found this code will be helpful?
For the original source, and hundreds more examples of PIC C code, see:
http://www.microchipc.com/sourcecode/#mmc
| Code: |
int mmc_init();
int mmc_response(unsigned char response);
int mmc_read_block(unsigned long block_number);
int mmc_write_block(unsigned long block_number);
int mmc_get_status();
/************************** MMC Init **************************************/
/* Initialises the MMC into SPI mode and sets block size, returns 0 on success */
int mmc_init()
{
int i;
SETUP_SPI(SPI_MASTER | SPI_H_TO_L | SPI_CLK_DIV_4 | SPI_SS_DISABLED);
*0x94 |= 0x40; // set CKE = 1 - clock idle low
*0x14 &= 0xEF; // set CKP = 0 - data valid on rising edge
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
for(i=0;i<10;i++) // initialise the MMC card into SPI mode by sending clks on
{
SPI_WRITE(0xFF);
}
OUTPUT_LOW(PIN_C2); // set SS = 0 (on) tells card to go to spi mode when it receives reset
SPI_WRITE(0x40); // send reset command
SPI_WRITE(0x00); // all the arguments are 0x00 for the reset command
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x95); // precalculated checksum as we are still in MMC mode
puts("Sent go to SPI\n\r");
if(mmc_response(0x01)==1) return 1; // if = 1 then there was a timeout waiting for 0x01 from the mmc
puts("Got response from MMC\n\r");
i = 0;
while((i < 255) && (mmc_response(0x00)==1)) // must keep sending command if response
{
SPI_WRITE(0x41); // send mmc command one to bring out of idle state
SPI_WRITE(0x00); // all the arguments are 0x00 for command one
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
i++;
}
if(i >= 254) return 1; // if >= 254 then there was a timeout waiting for 0x00 from the mmc
puts("Got out of idle response from MMC\n\r");
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
SPI_WRITE(0xFF); // extra clocks to allow mmc to finish off what it is doing
OUTPUT_LOW(PIN_C2); // set SS = 0 (on)
SPI_WRITE(0x50); // send mmc command one to bring out of idle state
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x02); // high block length bits - 512 bytes
SPI_WRITE(0x00); // low block length bits
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
if((mmc_response(0x00))==1) return 1;
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
puts("Got set block length response from MMC\n\r");
return 0;
}
/************************** MMC Get Status **************************************/
/* Get the status register of the MMC, for debugging purposes */
int mmc_get_status()
{
OUTPUT_LOW(PIN_C2); // set SS = 0 (on)
SPI_WRITE(0x58); // send mmc command one to bring out of idle state
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x00); //
SPI_WRITE(0x00); // always zero as mulitples of 512
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
return 0;
}
/************************** MMC Write Block **************************************/
int mmc_write_block(unsigned long block_number)
{
unsigned long i;
unsigned long varh,varl;
varl=((block_number&0x003F)<<9);
varh=((block_number&0xFFC0)>>7);
puts("Write block\n\r"); // block size has been set in mmc_init()
OUTPUT_LOW(PIN_C2); // set SS = 0 (on)
SPI_WRITE(0x58); // send mmc write block
SPI_WRITE(HIGH(varh));
SPI_WRITE(LOW(varh));
SPI_WRITE(HIGH(varl));
SPI_WRITE(0x00); // always zero as mulitples of 512
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
if((mmc_response(0x00))==1) return 1;
puts("Got response to write block\n\r");
SPI_WRITE(0xFE); // send data token
for(i=0;i<512;i++)
{
SPI_WRITE(i2c_eeprom_read(HIGH(i),LOW(i))); // send data
}
SPI_WRITE(0xFF); // dummy CRC
SPI_WRITE(0xFF);
if((SPI_READ(0xFF)&0x0F)!=0x05) return 1;
puts("Got data response to write block\n\r");
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
return 0;
}
/************************** MMC Read Block **************************************/
/**** Reads a 512 Byte block from the MMC and outputs each byte to RS232 ****/
int mmc_read_block(unsigned long block_number)
{
unsigned long i;
unsigned long varh,varl;
varl=((block_number&0x003F)<<9);
varh=((block_number&0xFFC0)>>7);
OUTPUT_LOW(PIN_C2); // set SS = 0 (on)
SPI_WRITE(0x51); // send mmc read single block command
SPI_WRITE(HIGH(varh)); // arguments are address
SPI_WRITE(LOW(varh));
SPI_WRITE(HIGH(varl));
SPI_WRITE(0x00);
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
if((mmc_response(0x00))==1) return 1; // if mmc_response returns 1 then we failed to get a 0x00 response (affirmative)
puts("Got response to read block command\n\r");
if((mmc_response(0xFE))==1) return 1; // wait for data token
puts("Got data token\n\r");
for(i=0;i<512;i++)
{
putc(SPI_READ(0xFF)); // we should now receive 512 bytes
}
SPI_READ(0xFF); // CRC bytes that are not needed
SPI_READ(0xFF);
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
SPI_WRITE(0xFF); // give mmc the clocks it needs to finish off
puts("\n\rEnd of read block\n\r");
return 0;
}
/************************** MMC get response **************************************/
/**** Repeatedly reads the MMC until we get the response we want or timeout ****/
int mmc_response(unsigned char response)
{
unsigned long count = 0xFFFF; // 16bit repeat, it may be possible to shrink this to 8 bit but there is not much point
while(SPI_READ(0xFF) != response && --count > 0);
if(count==0) return 1; // loop was exited due to timeout
else return 0; // loop was exited before timeout
}
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Thanks
_________________
NOway!! |
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temtronic
Joined: 01 Jul 2010
Posts: 9225
Location: Greensville,Ontario
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| Posted: Thu Feb 16, 2012 3:34 pm |
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First you MUST get the hardware correct.
Post your PIC information processor type.
It MUST be an L version(eg. 16LF887( if you want to connect direct to the MMC card
If you try to use an F version (eg. 16F887) you WILL destroy the MMC card...
Code is simple, but you MUST use the correct hardware. |
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exodia505
Joined: 07 Feb 2012
Posts: 34
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| Posted: Fri Feb 17, 2012 5:26 am |
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first of all , thanks
i want to use pic 16f877 , will i find difficulties? you mean needs 3.3 volts ?
i think this circuit will work (ofc its 16f873a) just need to change it to 877
what about code above ?is it good to use it or there is another one better ?[/img]
_________________
NOway!! |
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temtronic
Joined: 01 Jul 2010
Posts: 9225
Location: Greensville,Ontario
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| Posted: Fri Feb 17, 2012 6:48 am |
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That circuit will never work !!
Really, read the data sheets and see what are the required logic levels for the 16F877 PIC.
That PIC is 5 volt device, ALL MMC cards are 3 volts.
Hint. look at the charts/tables for min Vih for the PIC then ask if you can get that out of a 3.3volt MMC card.
if maxVohMMC < minVihPIC then 'can't be done'.
Simple math,no it's actually very simple arithmetic.. |
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exodia505
Joined: 07 Feb 2012
Posts: 34
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| Posted: Fri Feb 17, 2012 10:35 am |
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ok ok ok , let's back to software(code)
can you post a simple example of writting data (read from adc ) in MMC
using this function (mmc_write_block(address, size,*ptr);
!!!!!!!!!!!!!!!!!!
_________________
NOway!! |
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asmallri
Joined: 12 Aug 2004
Posts: 1634
Location: Perth, Australia
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| Posted: Fri Feb 17, 2012 1:11 pm |
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You are wasting your time using this processor.
Did you read the Kludge at the link you posted about using an EEPROM to buffer the writes for this processor?
Look for a pin compatible processor offering more RAM such as the PIC18F4620 to avoid this need for this messy and very very very slow KLUDGE.
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!
Last edited by asmallri on Sat Feb 18, 2012 3:41 am; edited 1 time in total |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Re: MMC Card |
| Posted: Fri Feb 17, 2012 3:18 pm |
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| exodia505 wrote: | I want to use MMC for simple application , who can give me an example?
Is MMC driver available in ccs ? |
RTFM.
Page 341, "Example programs" is a description of all the example programs that come with the CCS compiler. It even includes an mmc example.
Also have a look at the Code Library section of this forum, you will find two drivers there.
This website is full of examples for the High Tech compiler. This is a bad starting point as it requires knowledge of both the High Tech and CCS compiler to convert the programs. We are not going to do it for you, especially when CCS programs are ready available.
| Quote: | | ok ok ok , let's back to software(code) |
Without working hardware you will never be able to test the software.
One more important note on the hardware: Please, make it easier to yourself by using a PIC18 processor instead of PIC16. Writing to the MMC happens in blocks of 512 bytes and most PIC16's don't have this much RAM. The more RAM the better. Workarounds are possible for some situations, but difficult and not recommended for you as a beginner. |
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exodia505
Joined: 07 Feb 2012
Posts: 34
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| Posted: Sat Feb 18, 2012 8:18 am |
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Thanks !!
i'm working with pic 18f452 , it works well
_________________
NOway!! |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Sat Feb 18, 2012 8:51 am |
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The PIC18F452 doesn't run on 3V !!!
The PIC18LF452 does.
Save yourself a lot of trouble and have your whole circuit run on the same voltage as the MMC card.
Besides that, the PIC18F452 is old and not recommended for new designs. Many newer PIC18 processors exist that will run directly on 3V and are cheaper than the PIC18F452. |
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