Cannot switch from sinc5 filter to wideband filter

Dear community,

I am having real trouble trying to switch from the sinc5 filter to the wideband filter on the AD7768-8. Firstly I want to confirm that the code below works perfectly when using the sinc5 filter (CHANNEL_MODE_B_ADDR ((uint8_t)0X02); the value of 0b00001000;), so it is unlikely a coding issue but rather an instruction/protocol issue.

• I can confirm that I am writing to the channel mode register correctly as I am reading back the correct values.
  • I am writing to: CHANNEL_MODE_B_ADDR ((uint8_t)0X02); the value of 0b00000000; 
    
    • This should set the filter to the wideband filter and the decimation to be x32 according to the datasheet. I can confirm that reading this register back does indeed give me 0b00000000.
  • I can also confirm that I am using the right channel mode (channel mode B). i.e. register 0x03 is set to 0b11111111.
• In terms of the electrical connections
  • SYNC_OUT is directly connected to SYNC_IN. 
  • The START pin is connected to the micro (PSoC 6) and sends a 'start' signal after setting the register (above):
    • Cy_GPIO_Pin_FastInit(ADC_START_PORT, ADC_START_PIN, CY_GPIO_DM_STRONG, 1, HSIOM_SEL_GPIO); // this drives it out: HSIOM_SEL_GPIO
      Cy_SysLib_Delay(5); 
      Cy_GPIO_Write(ADC_START_PORT, ADC_START_PIN, 0);
      Cy_SysLib_Delay(5);
      Cy_GPIO_Write(ADC_START_PORT, ADC_START_PIN, 1);
    • I can confirm that I can see this signal on the scope and is being send correctly to the ADC
• I have also tried to 'sync' the filter change using the SPI method using the following code

  • // First reset the ADC
    ctrl_buffer.binaryValue = DATA_CTRL_SYNC_0;
    tx_buffer[0] = (ctrl_buffer.address << 8) | ctrl_buffer.binaryValue;
    adc_spi_writeburst(&tx_buffer[0], 1);
    Cy_SysLib_DelayUs(5000);

    ctrl_buffer.binaryValue = DATA_CTRL_SYNC_1;
    tx_buffer[0] = (ctrl_buffer.address << 8) | ctrl_buffer.binaryValue;
    adc_spi_writeburst(&tx_buffer[0], 1);
    
    

  • where:
    • #define DATA_CTRL_ADDR ((uint8_t)0x06); // DATA CONTROL: SOFT RESET, SYNC, AND SINGLE SHOT CONTROL REGISTER
    • #define DATA_CTRL_SYNC_0 0b00000000; // First send this for SYNC
      #define DATA_CTRL_SYNC_1 0b10000000; // Then send this for SYNC

Unfortunately, I do not get any data out on the DOUT0 and DOUT1 pins when doing this while I get the data clocking out perfectly when the sinc5 filter is selected. Any advice would be much appreciated.