ADC DMA Filter 16bits. Noise in VDD/2

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
lock attach
Attachments are accessible only for community members.
Anonymous
Not applicable

Hello,

I'm trying to configure a filter with 16 bits data from an ADC DelSig. I have configured the coherency to MID in the ADC and the filter and the "dalign" is enabled in the filter. I think that I have configured the DMA properly. Howver when I see the data filtered, it have some noise. Originally I was reading a sensor wih the ADC but later I have try with a potenciometer with the same result.The noise appear when the voltage cross VDD/2. What could be the problem? Thank you

FIR900HzPot.pngFIR900HzPot2.png

FIR900HzPot.png

0 Likes
2 Replies
odissey1
Level 9
Level 9
First comment on KBA 1000 replies posted 750 replies posted

Check ADC and DMA alignment and coherency settings to this

PSoC 5LP – 16 Bit and 24 Bit Digital Filter Code Examples - Hackster.io

Secondary, avoid channel B of the Filter as it seems to have a bug in the implementation

Filter Channel B 16 bit DMA issue

0 Likes
Anonymous
Not applicable

In my project I had configured the ADC and the Filter as the follow:

ADC

  • Coherency: MID (ADC_SetCoherency(ADC1_COHER_MID)

Fiter

  • Coherency: MID (Filter_SetCoherency(Filter_CHANNEL_A, Filter_KEY_MID))
  • Dalign: Enabled (Filter_SetCoherency(Filter_CHANNEL_A, Filter_KEY_MID))

DMA

  • ADC sample pointer: ADC_DelSig_DEC_SAMP_PTR
  • Filter Stage ponter: Filter_STAGEA_PTR

This configuration is found in the components Datasheets.

The sugested project has the follow confingurarion:

ADC

  • Coherency: LOW

Fiter

  • Coherency: MID (Filter_SetCoherency(Filter_CHANNEL_A, Filter_KEY_MID))
  • Dalign: Filter_DALIGN_REG =  Filter_DALIGN_REG | FILTER_DATA_ALIGN;  with FILTER_DATA_ALIGN = 0x05

DMA

  • ADC sample pointer: ADC_DelSig_DEC_SAMP_16B_PTR
  • Filter Stage ponter: Filter_STAGEA_PTR

However i have tried with the las confiuration and I have the same result. The problem could be the imput range with the 16bits resolution?

FIR900HzPot3.png

Thank you.

0 Likes