Electronic – Adapt fatFS library to PIC32

fatpicsd

I'm developing an application with PIC32MX, that record 3 WAV sounds and store theme into SD. Unfortunately the speed that I have reach is 155 kB/s and is insufficient for my application. Then I have to move fatFS, that use multi sector write speed wich seems to solve my problem. I download the latest library for fatFS here (bottom of the page). I read on the internet that this code is generic and only some part of code needs to be adapted, based on microcontroller in use.
I have spent many time trying to understand what are this portions of code, but I still dont'find theme.
Anyone can help me?

EDIT: Finally I understand how to modify the fatFS for adapt it to my system.
But I have a little poblem. After I properly modified the "platform dependent" section with correct SPI and chip select pin, I tryied to compile. I obtained an error about windows.h and tchar.h, included in file integer.h. But in integer.h I see the ifdef, and I want compile the "embedded" section, not the windows section. If I try to delete the ifdef, I obtained this error: " ';' expected but 'fs_type' found ". This come from typedef struct of ff.h.
On internet there are project with the identical structure, why this doesn't compile?

Best Answer

Microchip Harmony and MLA both contain good fast file access libraries, supporting multiple backing stores including SD, MMC, CF-II, USB MSD, etc. I suggest you give them a go since they are already tailored to the PIC32 chips.

Related Solutions

Electronic – PIC32: How to use DSP Library

I find this best learned using the DCMI tool and simulation, although mipsfir doesn't sim for some reason.

mips_fft16/32 does fft and ifft. Its all the same, really. Transfers input from one domain to the other.

Your implementation has flaws. The output of the mipsfft is a complex number, I am surprised that even compiled. Do a study on complex numbers. I don't see your fftc define, but a size of 1 doesn't make sense in the mips_fft16 call. Its really pretty simple. If you want to create a sine wave in a sample buffer of 32, you put the (amplitute*32)value in din[1].re. din[2].re for a double sine, and so on. So for a sample rate of 16000, 16000/32 = 500 * 1 = 500hz. Note that your output is in dout[x].re. So a call to fft/ifft will look more like this for a 32 sized fft. mips_fft16(dout, din, fftc16c32, scratch, 6);

Also, remember that the output of an fft is going to be real and imaginary, so if you just want peaks don't forget that A squared + B squared = C squared.

Real and imaginary = phase of output, greatly simplified.

OC1RS = (PR2 + 1) * ( ((float)dout2[pos])/1023); // Write new duty cycle

This isn't the proper way to do this at all. The OC1RS update can be anywhere, but I suggest putting in inside a timer at some chosen sample rate, say 16000. Then feed OC1RS with an incrementing data pointer of some sort to walk through your output.

Electronic – FatFs: Why am I not able to properly read sector 0

Turns out the answer had to do with the way I was implementing the SPI transactions using the Nordic SDK.

My rcvr_mmc function looked like this:

static
void rcvr_mmc (
    BYTE *buff, /* Pointer to read buffer */
    UINT bc     /* Number of bytes to receive */
)
{
    nrf_drv_spi_transfer(&spi, NULL, 0, buff, bc);
}

I assumed my rcvr_mmc was working since I was correctly parsing command responses. However, sector reads weren't working at all. I didn't even see a full 512*8 clock cycles.

Once I realized that was happened, I looked more closely at the Nordic SDK SPI driver and discovered this:

https://devzone.nordicsemi.com/question/66434/nrf_drv_spi_transfer-larger-transfer-size/

Since sector reads pass bc=512, this resulted in nothing really being read. My very inefficient hack for now to get this work is:

int i;
uint8_t small_buf[1];
for (i = 0; i < bc; i++) {
    nrf_drv_spi_transfer(&spi, NULL, 0, small_buf, 1);
    buff[i] = small_buf[0];
}

Related Topic