LPCXpresso LPC1114 SSP multi-sector read and write SD card

When working with the FatFs file system, I found that in order to increase the read and write speed of the SD card, a multi-sector read and write function is needed. Of course, many people's first reaction is that it can be achieved by calling a single-sector read and write function in a loop? For example:

uint8 i;

for (i=0; i < count; i++)

{

    MMCWriteSingleBlock(); // Single sector write

    MMCReadSingleBolck(); // Single sector read

}

In fact, it can be implemented in this way, but if it is implemented in this way, there will be no advantage of multi-sector reading and writing. The speed will not be improved at all. So we consult the SD card technology and get the following timing:

Let's first look at the read and write timing of the single sector and multi-sector of the SD card. It can be found that the timing is basically the same. It's just that the multi-sector read function needs to send a stop command after the reading is completed. The implementation function is as follows:

Check the timing, and then the following functions are very easy to understand, so I won't go into details. In fact, the functions written in the SD card are the same, first look at the following timing:

Similarly, we found that the timing of single-sector writing and multi-sector writing is basically the same, except that the multi-sector writing function has an additional "send 'stop transmission token'". That is, the stop token, the function is as follows:

Comparing the above timing and functions is very easy to understand, so I won’t go into details.

Through the above timing and function implementation, we know that the multi-sector read and write function is much more efficient than the single-sector read and write function. Of course, appropriate modifications to some codes in the function will further improve the execution efficiency. I will not go into details here. Netizens with programming experience know how to change it.

Let's take a look at the implementation of the main function:

The experimental results are as follows:

 IMG_3424.JPG  (40.69 KB)

2010-5-23 08:10

 IMG_3427.JPG  (45.85 KB)

2010-5-23 08:10