SPI 24 bit communication

Hi Ramesh,

ramesh rahi said:

    i think the problem is chip select pin .how to control spi chip select pin

Are you using SPISTEA or any GPIO? You can configure SPISTEA as GPIO19 and control the same manually.

Regards,

Gautam

The spi data register is left aligned.
You have to change it to
The SPI_write(mySpi, 0x16 << 8);

It is in the documentation but TI didn't made very much effect to make it easy to find.

i tried that one also .but it is not working

i have one doubt my controller spi buffer is 16 bit. for example i want to send 24 bit data how this one is possible ?

my part of code

//GPIO_setMode(myGpio, GPIO_Number_19, GPIO_19_Mode_GeneralPurpose);
//GPIO_setDirection(myGpio, GPIO_Number_19, GPIO_Direction_Output);
//GPIO_setPullUp(myGpio, GPIO_Number_19, GPIO_PullUp_Enable);

//GPIO_setHigh(myGpio, GPIO_Number_19);


// Setup a debug vector table and enable the PIE
PIE_setDebugIntVectorTable(myPie);
PIE_enable(myPie);

spi_init(); // Initialize SPI
spi_fifo_init(); // Initialize the SPI FIFOs

//SPI_write(mySpi, 0x0000 | 0x64<<1); // refer data sheet table 4 for shifting (64= wiper 40K)
//GPIO_setLow(myGpio, GPIO_Number_19);
SPI_write(mySpi, 0x00);
SPI_write(mySpi, 0x64<<1);
//GPIO_setHigh(myGpio, GPIO_Number_19);

Regards,
Ramesh

The out put of digital trim-pot is varying when i use gpio as SPISTEA

if i use SPISTEA pin as chip select digital trim-pot output is 40k
if i use GPIO pin as chip select digital trim-pot output is 70k


my code

// Initalize GPIO
GPIO_setPullUp(myGpio, GPIO_Number_16, GPIO_PullUp_Enable);
GPIO_setPullUp(myGpio, GPIO_Number_17, GPIO_PullUp_Enable);
GPIO_setPullUp(myGpio, GPIO_Number_18, GPIO_PullUp_Enable);
//GPIO_setPullUp(myGpio, GPIO_Number_19, GPIO_PullUp_Enable);
GPIO_setQualification(myGpio, GPIO_Number_16, GPIO_Qual_ASync);
GPIO_setQualification(myGpio, GPIO_Number_17, GPIO_Qual_ASync);
GPIO_setQualification(myGpio, GPIO_Number_18, GPIO_Qual_ASync);
//GPIO_setQualification(myGpio, GPIO_Number_19, GPIO_Qual_ASync);
GPIO_setMode(myGpio, GPIO_Number_16, GPIO_16_Mode_SPISIMOA);
GPIO_setMode(myGpio, GPIO_Number_17, GPIO_17_Mode_SPISOMIA);
GPIO_setMode(myGpio, GPIO_Number_18, GPIO_18_Mode_SPICLKA);
//GPIO_setMode(myGpio, GPIO_Number_19, GPIO_19_Mode_SPISTEA_NOT);

GPIO_setPullUp(myGpio, GPIO_Number_19, GPIO_PullUp_Enable);
GPIO_setMode(myGpio, GPIO_Number_19, GPIO_19_Mode_GeneralPurpose);
GPIO_setDirection(myGpio, GPIO_Number_19, GPIO_Direction_Output);


GPIO_setHigh(myGpio, GPIO_Number_19);


// Setup a debug vector table and enable the PIE
PIE_setDebugIntVectorTable(myPie);
PIE_enable(myPie);

spi_init(); // Initialize SPI
spi_fifo_init(); // Initialize the SPI FIFOs

GPIO_setLow(myGpio, GPIO_Number_19);
SPI_write(mySpi, 0x0000 | 0x64<<1); // refer data sheet table 4 for shifting (64= wiper 40K)
GPIO_setHigh(myGpio, GPIO_Number_19);

//GPIO_setLow(myGpio, GPIO_Number_2);
//SPI_write(mySpi, 0x00<<8);
//SPI_write(mySpi, 0x64<<9);
//GPIO_setHigh(myGpio, GPIO_Number_2);


Regards,
Ramesh

dear sir,

In my project i wants to communicate with ade7763 energy meter ic through SPI by using TMS320f28027 .

for example if i send mode register address (8 bit) 0x09 means it will return (16 bit) 0x000C from that register.now i checked the MISO signal by CRO it gives the same output 0x000C .but the value read by my spi code is data1= 255 and data2= 0

i tried with separate GPIO for cs .but the same problem is continuing .please help me to solve this problem

my code

while(1)
{

SPI_write(mySpi, 0x09<<8);
DELAY_US(6);
SPI_write(mySpi, 0x00); // dummy data 1
DELAY_US(4);
while(SPI_getRxFifoStatus(mySpi) == SPI_FifoStatus_Empty){
}
data1=SPI_read(mySpi);
SPI_write(mySpi, 0x00); // dummy data 2
DELAY_US(4);
while(SPI_getRxFifoStatus(mySpi) == SPI_FifoStatus_Empty){
}
data2=SPI_read(mySpi);

printf("data1:%d data2:%d\r\n",data1,data2);

for(i=0;i<100;i++)
DELAY_US(10000);
}


Regards
Ramesh

dear sir,

In my project i wants to communicate with ade7763 energy meter ic through SPI by using TMS320f28027 .

for example if i send mode register address (8 bit) 0x09 means it will return (16 bit) 0x000C from that register.now i checked the MISO signal by CRO it gives the same output 0x000C .but the value read by my spi code is data1= 255 and data2= 0

i tried with separate GPIO for cs .but the same problem is continuing .please help me to solve this problem

my code

while(1)
{

SPI_write(mySpi, 0x09<<8);
DELAY_US(6);
SPI_write(mySpi, 0x00); // dummy data 1
DELAY_US(4);
while(SPI_getRxFifoStatus(mySpi) == SPI_FifoStatus_Empty){
}
data1=SPI_read(mySpi);
SPI_write(mySpi, 0x00); // dummy data 2
DELAY_US(4);
while(SPI_getRxFifoStatus(mySpi) == SPI_FifoStatus_Empty){
}
data2=SPI_read(mySpi);

printf("data1:%d data2:%d\r\n",data1,data2);

for(i=0;i<100;i++)
DELAY_US(10000);
}


Regards
Ramesh

Ramesh,

I will reply to this question on the new post you created.

-Mark