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Altera_Forum's avatar
Altera_Forum
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16 years ago

Nios2 SPI

Hi,

I'm having some trouble reading from my IO expander with the SPI core from Altera :confused:

Can anybody provide me with an example on how to issue a correct read to the spi interface with the 'alt_avalon_spi_command' ??

Thanks :)

-mitch

7 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I use something like that 

     IOWR(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_TXDATA_REG, tosend);
    while (!(IORD(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_STATUS_REG) &  0x0020));
    return IORD(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_RXDATA_REG);
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I send 16bits. 1 read/write bit, 7 address bits and 8 datas bits. 

    void  WriteReg(alt_u8 adress, alt_u8 m_data)
{
    alt_u16 tosend;
    tosend = 0x8000 | ((adress << 8) & 0x7F00) | (m_data & 0x00FF);
    IOWR(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_TXDATA_REG, tosend);
    while (!(IORD(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_STATUS_REG) & 0x0020));
}
alt_u8  ReadReg(alt_u8 adress)
{
    alt_u16 tosend;
    tosend = (adress << 8) & 0x7F00;
    IOWR(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_TXDATA_REG, tosend);
    while (!(IORD(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_STATUS_REG) & 0x0020));
    return IORD(SPI_CYCLONE3_BASE, ALTERA_AVALON_SPI_RXDATA_REG);
}
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    16 years ago

    Hi

    I have the similar problem-i can write to the register, but when i try to read from register, i dont became anything, all signals-CS, CLK, MISO are 0...

    alt_spi_command run also, but only when i write to register...

    can anybody help me, any suggestion?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I ended up using the standard NIOS spi command like this:

    Write : 

     
wdata = 0x40; // Write command of the chip 
wdata = 0x09; // register adr
wdata = 0x2;  // value 
alt_avalon_spi_command(SPI0_BASE, 0,
3,
wdata,
0,
rdata,
0);

    Read : 

     
wdata = 0x41; // read command 
wdata = 0x12; // register adr 
ID = 0; 
alt_avalon_spi_command(SPI0_BASE, 0,
2,
wdata,
2, // reading 2 bytes 
rdata, // store bytes here 
0);

    Hope this helps :)

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    and how would that work without the standard command?

    I'm an altera newbee and have the same problem.

    i need to send 7 bit reg-addr.+1bit r/w and 16 bit data

    I'm trying with 

     
#include
<altera_avalon_spi_regs.h>
#include <altera_avalon_spi.h>
 
 
main{
int test;
 
while (!(IORD_ALTERA_AVALON_SPI_STATUS(SPI_BASE) & ALTERA_AVALON_SPI_STATUS_TRDY_MSK));
 
IOWR_ALTERA_AVALON_SPI_TXDATA(SPI_BASE, 0xFFFF);
 
while (!(IORD_ALTERA_AVALON_SPI_STATUS(SPI_BASE) & ALTERA_AVALON_SPI_STATUS_TRDY_MSK));
 
test=IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);
 
 
 
 
}

    but the thinks i write dont match with the read data... :(

    Any help?