AnsweredAssumed Answered

K22 FIFO Drain Flag RFDF not getting set

Question asked by Alberto Lubeiro on Sep 27, 2016
Latest reply on Sep 27, 2016 by EARL GOODRICH

Hi everybody,

Im working with a K22 and a M25P16 flash memory.

Im using the following function to communicate by SPI:

"void fnSPI_command(uint8_t ucCommand, uint32_t ulPageNumberOffset, volatile uint8_t *ucData, uint32_t DataLength)"


So far, i can read the manufacturer register and also the status register succsessfully.

When i try to write data, i see how the SPI signals MOSI, SCK ad CS are OK



But when i try to red the data:

   1- If i try to read 1 byte, i can't see anything at MISO and the code gets stuck at the first red code line.

   2- If i try to read at least 2 bytes, i can see 2 bytes at MISO but the code gets sutck at the second red code line


case READ_DATA_BYTES:  // read data from the chip
        WRITE_SPI1_CMD0((uint8_t)(ulPageNumberOffset >> 16));
        WRITE_SPI1_CMD0((uint8_t)(ulPageNumberOffset >> 8));
        ucTxCount = 4;
        SPI_FLASH_Danger = 1;   // mark that the chip will be busy for some time



if (ucTxCount != 0) {    //Read, with preamble writes?
        if ((ucTxCount == 1) && (DataLength > 1))
            WRITE_SPI1_CMD0(0xFF);           //We have to come out of here with two xmit cmds in FIFO, if at least 2 RX are coming
                //That's to make sure the TX FIFO keeps fully ahead of RX bytes and doesn't stall
        while (ucTxCount != 0) {                                             // while command bytes are going out
            if ((ucTxCount == 2) && (DataLength > 1))                       // before TX FIFO goes empty, put in 2 if we can!
                WRITE_SPI1_CMD0(0xFF);                                   // toss the associated RX bytes
            if (ucTxCount == 1)                                              // before TX FIFO goes empty, put in another
                if (DataLength == 1)                                         //Will this TX go with the last RX?
            // toss the associated RX bytes
           while( !(SPI1_SR & SPI_SR_RFDF_MASK) ) {}   IF I TRY TO READ A BYTE
            (void)  READ_SPI1_DATA();//*(volatile uint8_t *)(DSPI0_BLOCK + 0x38); // SPI0 POP RX FIFO Register (read-only);
            SPI1_SR |= SPI_SR_RFDF_MASK;



            while( !(SPI1_SR & SPI_SR_RFDF_MASK) ) {}   IF I TRY TO READ MORE THAN 2 BYTES
            *ucData++ = READ_SPI1_DATA();
            SPI1_SR |= SPI_SR_RFDF_MASK;
            if (DataLength == 2)                                         //Will this TX go with the last RX?
              if (DataLength > 2)
                WRITE_SPI1_CMD0(0xFF);                                   // Make an associated TX byte
          } while (DataLength != 0);



By the way, if i chage the value of ucTxCount = 1;//4; i receive data on MISO, i can't read it back from the function though. I get u8prueba = 0

fnSPI_command(READ_DATA_BYTES, 0x80001, &u8prueba, sizeof(u8prueba));



Any help will bw apreciated.


Thanks and best regards.