Tool/software:
I am having an issue with DAC81408EVM when trying to transmit more than 4 channels to DAC. If I only transmit 4 channels, everything is fine. If I try to transmit more than 4 channels, then the DAC will output for a couple of seconds and then stop all output. Not sure why this is happening. The following is my setup.
VAA 5V, VDD 5V, VIO 3.3V, VCC/VSS 9V, SPI Transfer Rate 20 MHz, Default DAC Range of 0 to 5V
My startup sequence is as follows:
Set Trigger Register (0x0E) with 0x000A for Soft Reset.
Set SPI Config Register (0x03) to 0x0A94 (default plus enable CRC checking and set device in active mode).
Read back SPI Config Register (0x03) and verify it is 0x0A94.
Set Broadcast Config Register (0x05) to 0xF00F (default plus disable Broadcast).
Read back Broadcast Config Register (0x05) and verify it is 0xF00F.
Set Sync Config Register (0x06) to 0x0FF0 (default plus DAC set to synchronous output in response to LDAC trigger).
Read back Sync Config Register (0x06) and verify it is 0x0FF0.
Set DAC Power Config Register (0x09) to 0xF00F (default plus power up the DAC output channels).
Read back DAC Power Config Register (0x09) and verify it is 0xF00F.
Then every 4 msecs I do the following:
Set DAC Output 0 Register (0x14)
Set DAC Output 1 Register (0x15)
Set DAC Output 2 Register (0x16)
Set DAC Output 3 Register (0x17)
Set Trigger Register (0x0E) with 0x0010 for LDAC trigger to synchronous DAC output
Read Status Register (0x02). If status indicates TEMP-ALM then Soft Reset via Trigger Register and repeat startup sequence. If status indicates CRC-ALM then clear Alarm Event via Trigger Register.
The above appears to work, I get good data on DAC Outputs 0, 1, 2 and 3.
If I add Set DAC Output 4 Register (0x18) to the sequence, then I get a couple of seconds of good data before all DAC outputs go to near zero volts (around 300 mV on oscilloscope). Status Register is not reporting any errors, previously SPI viewed timing on oscilloscope did not show anything unusual after moving from four to five channels.
Thanks in advance for any help you can provide me in resolving this issue.
Best regards,
Frank