BUF16821-Q1: Read NV Gamma value is one of four is not correct

Hi Fandy,

i have notified our expert regarding this topic. Please expect a response by 6/12/19.

Thanks,

Aaron

Hi Fandy,

Got couple of questions:

- Is this a write to DAC registers or EEPROM?

- Is this an immediate write to DAC register or not? ( D15=1 or 0 )

-The issue is the read back? That's a DAC output voltage issue, or just a read back issue?

What I understood:

- After power on  the routine write to DAC register 0 to 3 "376hex" and reads back:

-OUT1: 0x376( correct )

-OUT2:0x2ff ( wrong)

- OUT3:0x001(wrong)

-OUT4:0x2ff(wrong)

Does it happened with multiple parts or just 1?

Thanks,

Costin

Hi Costin

thanks,Please see below answer from customer

- Is this a write to DAC registers or EEPROM? ---A:EEPROM

- Is this an immediate write to DAC register or not? ( D15=1 or 0 ) --- A:  D15:0; D14:1

-The issue is the read back? That's a DAC output voltage issue, or just a read back issue? --- A: just a read back issue, Actual outpu voltage is OK.

What I understood:

- After power on  the routine write to DAC register 0 to 3 "376hex" and reads back:

-OUT1: 0x376( correct )

-OUT2:0x2ff ( wrong)

- OUT3:0x001(wrong)

-OUT4:0x2ff(wrong)

Does it happened with multiple parts or just 1? --- A:multiple parts

//--------------------------------

//Read DAC source code as follows,is it OK?

...

for(i=0; i<4; i++)        //Read out1~4
{
CTP_I2C_WriteDat_BUF16821(0x40|addr[i]);    // not sure is correct??
buf = CTP_I2C_ReadDat_BUF16821(addr[i]);
printf("\n gamma dat[%d]= 0x%x;",i,buf);
Delay_ms(50); 
}

...

//--------------------------------------
uint8_t CTP_I2C_WriteDat_BUF16821(uint8_t dat)
{
I2C_Start(); 

I2C_Send_Byte(0x74<<1);
if(I2C_Wait_Ack())
{
I2C_Stop();
return 1;
}

I2C_Send_Byte(dat);

if(I2C_Wait_Ack())
{
I2C_Stop();
return 1;
}

  I2C_Stop();  

return 0;
}

...

//-----------------
uint16_t CTP_I2C_ReadDat_BUF16821(uint8_t reg)
{
uint8_t tmp1,tmp2;
uint16_t tmp;

I2C_Start(); 

I2C_Send_Byte(0x74<<1);

if(I2C_Wait_Ack())
{
I2C_Stop();
return 1;
}

  I2C_Send_Byte(reg);
if(I2C_Wait_Ack())
{
I2C_Stop();
return 1;
}

I2C_Start(); 

I2C_Send_Byte((0x74<<1)|0x01);

if(I2C_Wait_Ack())
{
I2C_Stop();
return 1;
}

tmp1=I2C_Read_Byte();

I2C_Ack();

tmp2=I2C_Read_Byte();

I2C_NAck();

tmp = tmp1&0x03;
tmp = (tmp<<8) + tmp2;

I2C_Stop();

return tmp;
}

Hi Costin:

Thanks for your help.

//----------------------test mode1:

{ 
 buf = CTP_I2C_ReadDat_BUF16821(0x01);
 printf("\n Read 0x01 = 0x%x;",buf);
 
 buf = CTP_I2C_ReadDat_BUF16821(0x00);
 printf("\n Read 0x00 = 0x%x;",buf);
} 

UART Print:

 Read 0x01 = 0x2ff;
 Read 0x00 = 0x1;

//----------------------test mode2:

{ 
 buf = CTP_I2C_ReadDat_BUF16821(0x00);
 printf("\n Read 0x00 = 0x%x;",buf);
 buf = CTP_I2C_ReadDat_BUF16821(0x01);
 printf("\n Read 0x01 = 0x%x;",buf);
} 

UART Print:

 Read 0x00 = 0x376;

 Read 0x01 = 0x2ff;

//--------------

Result: just test mode2 first output is correct

============================================

my question:

as BUF16821 DS page14 describtion:

"To read the data present in nonvolatile register for a particular DAC/VCOM channel, the master must first issue a general acquire command, or a single acquire command with the appropriate DAC/VCOM channelchosen."

can you give me an example code?  (Email: guicai_wang2@tianma.cn)

Thanks a lot.

Dear  Costin:

i find another issue:

if write dat "0x2ea" to NV 0x00 address,the read dat is not correct:

//-----------------

addr[0]=0x00;
dat[0]=0x2ea;
CTP_I2C_WriteReg_BUF16821(addr[0],0x4000|dat[0]);
buf = CTP_I2C_ReadDat_BUF16821(addr[0]);
printf("\n gamma dat[0]= 0x%x;",buf);

UART Print: gamma dat[0]= 0x2ff;

//----------------

change the write dat  "0x300",and write to the NV same address,the read dat is OK:

//---------------

addr[0]=0x00;
dat[0]=0x300; 
CTP_I2C_WriteReg_BUF16821(addr[0],0x4000|dat[0]); 
buf = CTP_I2C_ReadDat_BUF16821(addr[0]);
printf("\n gamma dat[0]= 0x%x;",buf);

UART Print: gamma dat[0]= 0x300;

//--------------

I do not know WHY?

Hi

The number of write to NV should not exceed 16

I’ll get back to you next week, this week I don’t have

data sheet access

Regards,

Costin