CS5460A to 8051/8052: How to read data

[Pachi]

Hello

I am facing a problem interfacing the Cirrus CS5450A to Atmel 89C51/ 89C52 microcontroller.

I want to know how to read data from the 5460A. The SCK, SDO, SDI pins are being read through T0, T1 and WR pins (Port 3 pins 4,5,6). I went through the datasheet of 5460 and tried some code, but the bytes read are some arbitrary value.
Following is the code:



void read_data (void)
{
write_to_register(0xE8, 0xFF, 0xFF, 0xFF); //Start conv, Nop, Nop, Nop
write_to_register(0xFF, 0xFF, 0xFF, 0xFE); //Sync1, Sync1,Sync1,Sync0
read_register(0x0E); //Read Current Register
}

void write_to_register(char command,char low,char mid,char high)
{
transfer_byte(command);
transfer_byte(high);
transfer_byte(mid);
transfer_byte(low);
return;
}

void read_register(char command)
{
transfer_byte(command);
high_byte = recieve_byte(); /*Receive Bytes*/
mid_byte = recieve_byte();
low_byte = recieve_byte();
return;
}


void transfer_byte(char number)
{
unsigned int q, x, b[8];
for(q = 7; q != 0; q--) //convert to binary
{
x = number / (1 << q);
number = number - x * (1 << q);
b[q]=x;
}
SCLK=0;

for (q=7; q!=0; q--)
{
SDI= b[q]; //place bit to transmit
SCLK=1; SCLK=0; //pulse the clock
}
SDI=1;
return;
}


char recieve_byte(void)
{
unsigned int i;
unsigned char x[8], sync[8]="11111110";
SDI=1;
for (i=0; i<8; i++)
{
x=SDO; //receive bit
SDI= sync; //datasheet says Sync0 should be strobed on SDI
//while reading from SDO

SCLK=1; SCLK=0; //pulse the clock
}
return x;
}

Added after 20 minutes:

The output is:
high_byte= mid_byte= low_byte =10

Also, the write_to_register function calls are making no effect (same output without them). Without read_register, the values are 0 each, so read_register does work, but not properly (it always shows these values no matter what the current/voltage read is)

 

[mandar_mahajan]

kindly refer the following link, it may help u.

 

[Pachi]

I read through that post and implemented the initializations. but there still seems to be a problem. the 24 bit data read is still 00 00 00. Here's the modified code.

void begin()
{
unsigned int i;
RESET=0; //initial reset
SDelay(100);
RESET=1;

write_to_register(0x5E, 0x00, 0x00, 0x01); //status reg= 000001
write_to_register(0x40, 0x00, 0x00, 0x04); //config reg= 000004
write_to_register(0x4A, 0x00, 0x00, 0x32); //cycle count=000032
write_to_register(0x78, 0x00, 0x00, 0x08); //control reg=000008
write_to_register(0x74, 0x80, 0x00, 0x00); //mask reg= 800000
write_to_register(0xE8, 0xFF, 0xFF, 0xFF); //start conv, nop, nop, nop
write_to_register(0xFF, 0xFF, 0xFF, 0xFE); //nop, nop, nop, nop

read_register(0x0E); //read inst current reg
SDelay(200); //delay

for (i=0;i<50;i++)
{
P2=0xFF; led1=0; P0=Display((high_byte>>4)& 0x0F); //Display High
SDelay(300);
P2=0xFF; led2=0; P0=Display((high_byte)& 0x0F);
SDelay(300);

P2=0xFF; led3=0; P0=Display((mid_byte>>4)& 0x0F); //Display Mid
SDelay(300);
P2=0xFF; led4=0; P0=Display((mid_byte)& 0x0F);
SDelay(300);

P2=0xFF; led5=0; P0=Display((low_byte>>4)& 0x0F); //Display Low
SDelay(300);
P2=0xFF; led6=0; P0=Display((low_byte)& 0x0F);
SDelay(300);
}
return;
}

void write_to_register(char command,char low,char mid,char high)
{
transfer_byte(command); //Transfer command followed by 24 bit data
transfer_byte(high);
transfer_byte(mid);
transfer_byte(low);
return;
}


void read_register(char command)
{
transfer_byte(command);
high_byte = recieve_byte(); //Receive Bytes
mid_byte = recieve_byte();
low_byte = recieve_byte();
return;
}

void transfer_byte(char number)
{
unsigned int i;
for (i=0; i<8; i++)
{
if (number & 0x80) SDI=1; //bit to be transferred is put on SDI
else SDI=0;

SDelay(100); //delay
SCLK=1; SDelay(100); SCLK=0; SDelay(100); //pulse clock

number = number<<1; //next bit
}
return;
}


char recieve_byte(void)
{
unsigned int i;
unsigned char x, sync=0xFE;
SDI=1;
for (i=0; i<8; i++)
{
x=x|SDO; //bit recieced from SDO is stored
x=x <<1;

if(sync &0x80) SDI=1; //strobing nop on SDI while reading
else SDI=0; //as per 5460 datasheet
sync= sync<<1;

SDelay(100); //delay
SCLK=1; SDelay(100); SCLK=0; SDelay(100); //pulse clock
}
return x;
}

Added after 26 minutes:

I also tried writing to the register im reading.

write_to_register(0x4E, 0xFF, 0xFF, 0xFF); //write instead of start conv, nop, nop, nop
write_to_register(0xFF, 0xFF, 0xFF, 0xFE); //nop, nop, nop, nop

no change.

 

[mandar_mahajan]

I hav not gone through ur code, but just try it with pins other thanTo & T1 of controller.

 

[Pachi]

The circuit is hardwired on a PCB. cant change it. i think its a software problem.