DAC61404: Read and Write register

I read it three times but returned value is 800000

I writed 80ABCD

Hi,

share code 

FPGA  Nios II

SPI Mode 1

SPI CLk 1MHZ

//------------------Write to NOP  ---------------
addr = 0x00;
data = 0xabcd;
isWrite = 1;
ret = pkgCmd(addr, data, isWrite);
printf("写NOP寄存器 %06X\n", (unsigned int)ret);

tx_data_array[0] = ret;
rx_data_array[0] = 0x000000;
SPI_OLED_WR(tx_data_array, rx_data_array, len);

//--------------------Read From NOP--------------
isWrite = 0;
addr = 0x00; //地址
ret = pkgCmd(addr, data, isWrite);
tx_data_array[0] = ret;
rx_data_array[0] = 0x000000;
SPI_OLED_WR(tx_data_array, rx_data_array, len);
SPI_OLED_WR(tx_data_array, rx_data_array, len);
printf("------- 读 NOP 寄存器 %06X\n", (unsigned int) (rx_data_array[0]));

/**
* SPIWrite Func
*/
void SPI_OLED_WR(alt_u32* tx_data, alt_u32* rx_data, int len) {
wifi_spi_command_pc(SPI_CTRL_CARD_BASE, 0, len, tx_data, len, rx_data, 0);
/*alt_avalon_spi_command(SPI_CTRL_CARD_BASE, 0,
len, tx_data, len, rx_data, 0);*/
}
;

//Pkg  CMD

alt_u32 pkgCmd(alt_u8 addr, alt_u16 data, int isWrite) {
alt_u32 ret = 0x000000;
ret = (addr << 16) | data; //8 + 16 = 24位
if (isWrite == 1) {
//写操作 最高位置0
ret = ret & 0x7fffff;
} else {
//读操作 最高位置1 1000 0000 ff ff ff ff
ret = ret | 0x800000;
}

return ret;
};

//----------------------------------spi func-----------------------------------------------------------

/******************************************************************************
* *
* License Agreement *
* author: pc
* pcjiushizhu@qq.com
******************************************************************************/

#include "alt_types.h"
#include "wifi_spi_base.h"
#include "altera_avalon_spi_regs.h"
#include "altera_avalon_pio_regs.h"
#include "io.h"
#include "system.h"
#include <unistd.h> // usleep()

#define READ_NOW
#define DELAY 1

int wifi_spi_command_pc(alt_u32 base, alt_u32 slave,
alt_u32 write_length, alt_u32 * write_data,
alt_u32 read_length, alt_u32 * read_data,
alt_u32 flags)
{
const alt_u32 * write_end = write_data + write_length;

alt_u32 status;

/* Warning: this function is not currently safe if called in a multi-threaded
* environment, something above must perform locking to make it safe if more
* than one thread intends to use it.
*/

IOWR_ALTERA_AVALON_SPI_SLAVE_SEL(base, 1 << slave);

/* Set the SSO bit (force chipselect) only if the toggle flag is not set */
if ((flags & ALT_AVALON_SPI_COMMAND_TOGGLE_SS_N) == 0) {
IOWR_ALTERA_AVALON_SPI_CONTROL(base, ALTERA_AVALON_SPI_CONTROL_SSO_MSK);
}

//2016.5.5，增加同步操作，同步线操作，拉高同步头，主程序没有改。
IOWR(PIO_SYNC_BASE,0, 0x01);

/*
* Discard any stale data present in the RXDATA register, in case
* previous communication was interrupted and stale data was left
* behind.清空rx
*/
IORD_32DIRECT(base,0);

/* Keep clocking until all the data has been processed. */
for (;;) {
//------------发送数据 --------------
do {
status = IORD_8DIRECT(base,8); //读SPI的status寄存器
} while ((status & 0x40) != 0x40); //TRDY=1表示txdata寄存器空，可以发起新的一次写入，TRDY=0则等待

{
if (write_data < write_end) {
IOWR_32DIRECT(base,4,(*write_data));
write_data++;
}
}
// usleep(10); //如果优化级别高了，就需要延时了。
//------------紧接着接收数据------------
do {
status = IORD_8DIRECT(base,8); //读SPI的status寄存器
} while ((status & 0x80) != 0x80); //RRDY=1表示rxdata寄存器满，可供读取，RRDY=0则等待

{
alt_u32 rxdata = IORD_32DIRECT(base,0);
(*read_data) = rxdata;
read_data++;

if (write_data == write_end)
break;
}

// usleep(10);//如果优化级别高了，就需要延时了。
}

/* Wait until the interface has finished transmitting */
do
{
status = IORD_ALTERA_AVALON_SPI_STATUS(base);
}
while ((status & ALTERA_AVALON_SPI_STATUS_TMT_MSK) == 0);

/* Clear SSO (release chipselect) unless the caller is going to
* keep using this chip
*/
if ((flags & ALT_AVALON_SPI_COMMAND_MERGE) == 0){
// int i=1000, j=1000;
// for(i=1000;i>0;i--){
//// for(j=1000;j>0;j--){
//// ;
//// }
// }
IOWR_ALTERA_AVALON_SPI_CONTROL(base, 0);
// usleep(5);
}
//同步线操作，拉低同步头
IOWR(PIO_SYNC_BASE,0, 0x00);
return read_length;
}

Hi, I will get back to you after reviewing code. 

1st read;

1. Write NOP with register address to be read back

//------------------Write to NOP  ---------------
addr = 0x00;
data = 0xabcd;
isWrite = 1;
ret = pkgCmd(addr, data, isWrite);
printf("写NOP寄存器 %06X\n", (unsigned int)ret);

tx_data_array[0] = ret;
rx_data_array[0] = 0x000000;
SPI_OLED_WR(tx_data_array, rx_data_array, len);

2. dummy read cycle ; read back data from previous set address 

//--------------------Read From NOP--------------
isWrite = 0;
addr = 0x00; //地址
ret = pkgCmd(addr, data, isWrite);
tx_data_array[0] = ret;
rx_data_array[0] = 0x000000;
SPI_OLED_WR(tx_data_array, rx_data_array, len);
SPI_OLED_WR(tx_data_array, rx_data_array, len);
printf("------- 读 NOP 寄存器 %06X\n", (unsigned int) (rx_data_array[0]));

2nd read;

repeat above step 1 & 2

3rd read;

repeat above step 1 & 2

please try above sequence in your code.

Thanks