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Tool/software:
Hi there,
I've been looking at the DAC81401 and its EVM for an application as a waveform generator with an output range from +/-24V. The chip seems to fit our needs well in terms of operating ranges, but I am a bit unclear on the register setting and how, if possible, to set it in the EVM (and then later with the chip itself) to control the waveform of the output such as a sine wave or a square wave of programmable frequency/burst durations.
I appreciate the the help on the subject.
Thanks
Hi Samuel,
Please check the steps below for getting the ± 24V output on the DAC81401EVM -
Step - 1 jumper settings :
please refer to the figure : 3-1 in the DAC81401 EVM's user guide and table 3-2. DAC81401EVM jumper summary for more details
Step - 2 power supply settings :
• AVDD : 0 to 41.5 V (default + 15 V)
• AVSS : 0 to -21.5 V (default - 15 V)
• DVDD : 4.5 V to 5.5 V (default + 5 V)
• IOVDD : 1.7 V to 5.5 V (default 1.8V or 3.3 V or 5.0 V)
• (AVDD - AVSS) must not be greater than 43 V
• EXT HV POS (V+) - EXT HV NEG : ± 4 V to ±42.5 V or 8 V to 85 V (± 25 V for your application )
Step - 3 registers settings :
• Write 0x0A04 to the SPI_CONFIG (0x03) register to power up the device
• Write 0x0000 to the GEN_CONFIG (0x04) register to power up the internal reference
• Write 0xFFFE to the DAC_PWDWN (0x09) register to power up the DAC output
• Write 0x000D to the DACRANGE (0x0A) register to configure the DAC in ±6‑V range, this will give you ±24‑V after gain stage.
• Write 0x000D to the DACRANGE (0x0A) register to configure the DAC in ±6‑V range, this will give you ±24‑V after gain stage.
• Write 0x0000, 0x7FFF or 0xFFFF to the DAC (0x10) register to get -24V, 0V and +24V at the gain stage output.
Thanks,
Sanjay
Hi Sanjay,
Thanks for the response.
I understand the register settings for yielding the +/- 24V, my question is regarding how one can configure the DAC's waveform to generate square waves and/or control the frequency of the output, if this is possible.
Thanks
Essentially, I am looking to confirm that the DAC can generate arbitrary waveforms based on register setting configurations.
Hi Samuel,
Yes, this DAC can generate square or sinusoidal wave but it needs software to calculate and generate the corresponding codes. There is no inbuilt feature in this DAC for generating the square or sine wave.
To help you better in this context, I would like to know what's the spec that you are looking here, as in frequency range, THD value, accuracy, etc ?
Thanks,
Sanjay
Thanks Sanjay!
Does the GUI software associated with the EVM for this chip (DAC81401EVM) allow for the calculation and generation of these codes? If not, am I able to input a series of codes for the module to execute through to generate a desired output waveform or doesit not allow for inputting a sequence of codes?
We are looking to generate around a 5kHz sqaure wave burst that lasts around 200 microseconds. The other factors are more flexible.
Hi Samuel,
No, GUI doest not support for the calculation and generation of these codes.
But you can generate the sequence of codes in python and write that sequence codes through onboard FTDI module or any external SPI controller module. And you should be able to generate the 5 kHz sine wave of 200ms duration.
Disable the FTDI SPI via J22 and use the J12 connector in case you want to use the external SPI controller.
DAC81401EVM User's guide
And what is the update rate that are looking for here ?
Thanks,
Sanjay
Hi Sanjay,
That is perfect, thank you for clearing that up!
No exact number for the update rate yet, but likely north of 200kHz. Maybe around 300-400k
Thanks,
Samuel