Interfacing DAC6571 using I2c with RT1020

[hanmant]

Hi all,

I have interfaced DAC6571 using I2c with i.Mx RT1020 processor.

i have used i2c DMA example from SDK.

I'm facing issue to write data on DAC ; it behaving very random .Not able set proper values on DAC.

Please guide me .

[hanmant]

Thanks for reply .

both line have 4.7K pull up. please check code and configuration:

#define I2C_SLAVE_DAC6571_ADDR_7BIT 0x4CU//(0x98U >> 1)

#define DAC_MASK_VALUE 0x03FF

   // DAC value should be 10 bits, so mask it to ensure it doesn't exceed 10 bits

   value &= DAC_MASK_VALUE;

   // Prepare the data to be sent in the required format

   BYTE data[2];

   data[INDEX0] = value >> SHIFT_8BIT; // Upper 8 bits

   data[INDEX1] = value & MAX_8BIT;     // Lower 8 bits

   // LPI2C master descriptor

   lpi2c_master_transfer_t masterXfer = {0};

   status_t reVal = kStatus_Fail;

   /* subAddress = 0x01, data = g_master_txBuff - write to slave.

start + slaveaddress(w) + subAddress + length of data buffer

+ data buffer + stop*/

   masterXfer.slaveAddress   = I2C_SLAVE_DAC6571_ADDR_7BIT;

   masterXfer.direction      = kLPI2C_Write;

   masterXfer.data           = data; //(0 to 1023)

   masterXfer.dataSize       = sizeof(data);

   masterXfer.flags          = kLPI2C_TransferDefaultFlag;

   // Send master non-blocking data to slave

   reVal = LPI2C_MasterTransferEDMA(I2C_MASTER, &g_m_edma_handle, &masterXfer);

   if (reVal != kStatus_Success)

   {

   return DAC_STATUS_FAIL;

   }

      // Wait for transfer completed.

   while (!g_MasterCompletionFlag)

   {

// Do Nothing

   }

   g_MasterCompletionFlag = false;

[mayliu1]

Hi @hanmant ,

Thank you for your interest in the NXP MIMXRT product, I would  like to provide service for you.

I check dac6571.pdf, It describe as follows.

The data you need to send is split into two parts.

But in software code, you  split data for 8bit.

 So, I think it is the reason why data is random. Please send data as the dac6571.pdf  described.

Wish it helps you.
If you still have question about it, please kindly let me know.

Best Regards

mayliu

[mayliu1]

Hi @hanmant ,

Thank you for your interest in the NXP MIMXRT product, I would  like to provide service for you.

I think the PD1 and PD0 setting is not correct. If you want DAC6571 work normal, PD1 and PD0 should set as 0.

Wish it helps you.
If you still have question about it, please kindly let me know.

Best Regards

mayliu

[hanmant · Accepted solution]

Thank for reply 

below is updated code but still it not working .

when i set if value = 500; then dac output should be like half of 3.3V .

but it giving like 3v sometimes or any random 

(you checked pin configuration , is it correct? please confirm) 

BYTE data[2];

data[INDEX0] = (value >> 6) & 0x0F; // Upper 4 bits of the 10-bit value

data[INDEX0] |= 0x00; // Set the two zeros and two power-down bits (00 11 XXXX)

data[INDEX1] = (value << 2) & MAX_8BIT; // Lower 6 bits of the 10-bit value followed by two don't care bits

// LPI2C master descriptor

lpi2c_master_transfer_t masterXfer = {0};

status_t reVal = kStatus_Fail;

/* subAddress = 0x01, data = g_master_txBuff - write to slave.

start + slaveaddress(w) + subAddress + length of data buffer

+ data buffer + stop*/

masterXfer.slaveAddress = I2C_SLAVE_DAC6571_ADDR_7BIT;

masterXfer.direction = kLPI2C_Write;

masterXfer.data = (UINT8*)data; //(0 to 1023)

masterXfer.dataSize = sizeof(data);

masterXfer.flags = kLPI2C_TransferDefaultFlag;

// Send master non-blocking data to slave

reVal = LPI2C_MasterTransferEDMA(I2C_MASTER, &g_m_edma_handle, &masterXfer);

[mayliu1]

Hi @hanmant ,

Thank you for your interest in the NXP MIMXRT product, I would  like to provide service for you.

SCL and SDA pin configuration should set as open drain.

Wish it helps you.

Best Regards

mayliu

[mayliu1]

Hi @hanmant ,

Thank you for your interest in the NXP MIMXRT product, I would  like to provide service for you.

I think RT1020 EVK I2C communication is normal work, the problems is about how control chip DAC6571.

I suggest you check DAC6571 data sheet in detail, Special pay attention to I2C write and read protocol.

For example:

1: Do you have set DAC6571 Configuration Register.

A Basic Guide to I2C (ti.com.cn)

2: Do you confirm I2C communication protocol is correct.

+2.7 V to +5.5 V, I2C Interface, Voltage Output 10-Bit DAC datasheet (Rev. B) (ti.com.cn)

 Please use a logic analyzer or an oscilloscope to check I2C protocol is correct as you send

Wish it helps you.
If you still have question about it, please kindly let me know.

Best Regards 

mayliu

[hanmant]

Thanks for reply .

whatever i configured it not correct?

[mayliu1]

Hi @hanmant ,

Thank you for your interest in the NXP MIMXRT product, I would  like to provide service for you.

I think RT1020 I2C communication work correctly. What I support before is out of my scope.

Chip DAC6571 is TI company's production, maybe you can contact DAC6571 supporter.

Wish it helps you.

Best Regards

mayliu

[hanmant]

i set like this .but not working

BYTE data[3];

data[INDEX0] = (value >> 6) & 0x0F; // Upper 4 bits of the 10-bit value

data[INDEX0] |= 0x30; // Set the two zeros and two power-down bits (00 11 XXXX)

data[INDEX1] = (value << 2) & MAX_8BIT; // Lower 6 bits of the 10-bit value followed by two don't care bits

[mayliu1]

Hi @hanmant ,

Thank you for your interest in RT MIMXRT product, I would like to provide service for you.

I would like you to confirm that the following points are correct.

1： whether the SDA and SCL hardware has pull-up resistors, and whether the I2C DMA demo software is configured in open-drain mode.

2：Please check if the address configuration for the DAC6571 chip is correct. If you are controlling the output, you should use the Address Byte, not Broadcast Address.

If it's convenient, please use a logic analyzer or an oscilloscope to check if each acknowledge bit of the I2C protocol is correctly pulled low.

3：Please confirm that the I2C configuration in the RT1020SDK demo is consistent with the configuration for the DAC6571.

Wish it helps you.

If you still have question about it, please kindly let me know.

Best Regards

mayliu