NFCのトピックNHS3152 DAC, Single-Shot vs Continuous

NHS3152 DAC, Single-Shot vs Continuous

rcorder — Mon, 10 Sep 2018 19:33:07 GMT

I tried ADCDAC0 example code from the NHS31xx SW API doc:

Example-1 Single Shot Digital-to-Analog Conversion with Polling

   Chip_ADCDAC_Init(NSS_ADCDAC0);
   Chip_IOCON_SetPinConfig(NSS_IOCON, IOCON_ANA0_0, IOCON_FUNC_1);
   Chip_ADCDAC_SetMuxDAC(NSS_ADCDAC0, ADCDAC_IO_ANA0_0);
   Chip_ADCDAC_SetModeDAC(ADCDAC_IO_ANA0_0, ADCDAC_SINGLE_SHOT);
   Chip_ADCDAC_WriteOutputDAC(NSS_ADCDAC0, 3000);

I got a voltage pulse, then it returns to zero.

If I change the SetModeDAC to ADCDAC_CONTINUOUS, the voltage is held at the appropriate level.

Shouldn't the Output Hold Amplifier keep the output voltage continuous in Single-Shot, or what am I missing?

Re: NHS3152 DAC, Single-Shot vs Continuous

Kan_Li — Fri, 14 Sep 2018 10:09:23 GMT

Hi，

I am sorry, but from my understanding, that is just what single-shot should behave, otherwise what is the difference between single-shot and continuous mode?

Have a great day,
Kan

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Re: NHS3152 DAC, Single-Shot vs Continuous

driesmoors — Fri, 14 Sep 2018 11:52:21 GMT

Hi,

I asked around, and your observations are correct. The DAC functionality is not in a separate HW block, but is provided by the ADC HW block. The NHS3152 IC cannot hold the voltage level for a long duration in single-shot mode. If you need this, you must perform the conversion continually, as you already found out.

Kind regards,
Dries.

Re: NHS3152 DAC, Single-Shot vs Continuous

rcorder — Fri, 14 Sep 2018 12:28:28 GMT

Dries, Thanks for checking on this for me.

Has there been any characterization about the output "hold" amplifier (I used "" because it doesn't hold very long). Single-Shot mode doesn't seem too useful if 1) it doesn't hold, or 2) its decay isn't characterized.

Rod

Re: NHS3152 DAC, Single-Shot vs Continuous

driesmoors — Tue, 25 Sep 2018 08:30:15 GMT

Hi rcorder@corder-eng.com,

I could not find any characterization. As you said, single-shot mode just isn't very useful here. Also, decay is dependent on the other connection of the analog line.

Best,
Dries.