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AD5755-1 Not Responding

Hi,

We have purchased AD5755-1 Eval board and able to generate DAC voltages in the Eval board which we bought. Later we made our own custom board for AD5755-1, along with other peripherals. The custom board were not able to give DAC voltages, later when we checked SPI lines using oscilloscope, the MISO lines were not giving anything to master, while CS,MOSI,SCK were going to slave.

Hardware Settings in Eval board :

LDAC ->GND,CLEAR ->GND,POC ->GND,RESET ->DVDD .

Software Code For Generating DAC Voltage :

{0x7c,0x85,0x55};  // Software Reset , As AD0 = AD1 = 1

{0x7c,0x60,0x04};  // DC [Default settings only]

{0x7c,0x41,0x03};  // DAC Ch-A Setting [-10--+10V]

{0x7d,0x41,0x03};  // DAC Ch-B Setting [-10--+10V]

{0x60,0xff,0xff};  // DAC Ch-0 Value

{0x61,0xcf,0xff};  // DAC Ch-1 Value

{0x7c,0x20,0x30}; //OUTEN_ALL,DCDC_ALL

Above are the Software and Hardware settings in Eval board and we are able to measure programmed DAC voltages in Eval board. But same Code in custom hardware is not giving required voltages.

We also tried reading DC register using {0xfa,0x00,0x00} and nop {0x7c,0xe0,0x00}. In Eval board, its giving required register value, where as in custom board its not giving anything (Also verified using oscilloscope).

Kindly look into the issue and help me to resolve the issue, Thanks in Advance

Notes:

We are using SC18IS602B, i2c-spi convertor for using spi communication. CS0 is connected to AD74412R and CS1 is connected to AD5755-1.

The MOSI and MISO after SC18IS602B, were wrong in schematics and swapped for proper functioning.

AD74412R, connected to other channel is working fine

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