Problem with SPI (Cyclone II)

Hello,

First of all, many thanks for your reply Daixiwen and I am sorry for my delay to answer.

I have got an oscilloscope and could see the spi signals. The mistake must make in this reception part of my code. This part is:

// last byte of spi memory address

// wait to transmit

wdata=0xf0;

while ((iord_altera_avalon_spi_status(spi_base) & altera_avalon_spi_status_trdy_msk)==0);

// send data

iowr_altera_avalon_spi_txdata(spi_base,wdata);

////////////// wait the end of transmission //////////////

while ((iord_altera_avalon_spi_status(spi_base) & altera_avalon_spi_status_tmt_msk)==0);

// wait to receive

while ((iord_altera_avalon_spi_status(spi_base) & altera_avalon_spi_status_rrdy_msk)==0);

// clean data

iord_altera_avalon_spi_rxdata(spi_base);

iowr_altera_avalon_spi_status(spi_base,0x00);

////// dummy bite to read the spi memory ifnormation

// wait to transmit

wdata=0x00;

while ((iord_altera_avalon_spi_status(spi_base) & altera_avalon_spi_status_trdy_msk)==0);

// send data

iowr_altera_avalon_spi_txdata(spi_base,wdata);

// wait the end of transmission

while ((iord_altera_avalon_spi_status(spi_base) & altera_avalon_spi_status_tmt_msk)==0);

// wait to receive

while ((iord_altera_avalon_spi_status(spi_base) & altera_avalon_spi_status_rrdy_msk)==0);

// read data

led_val=iord_altera_avalon_spi_rxdata(spi_base);

iowr_altera_avalon_spi_status(spi_base,0x00);

//disable cs

iowr_altera_avalon_spi_control(spi_base,~altera_avalon_spi_control_sso_msk);

usleep(25);

// display data

iowr_altera_avalon_pio_data(led_base,led_val);

The problem is when I send to the spi memory the last byte of the address which I want to read (emphasized in bold). The MOSI signal appears in the oscilloscopi such as I expected. By contrast, the MISO signal is not working when the spi memory, in principle, is sending the data of the desired address (0x0000F0). I have already checked the hardware connection several time, so I think the mistake must be by software.

I would be very grateful if anyone could give a piece of advice about my problem.

Many thanks,