TMS320F280025C: Questions about ADCDACLOOPBACK register in Analog Subsystem

Matt Dash

Prodigy 240 points

Part Number: TMS320F280025C

Hi, experts,

may you have a nice day!

TRM says it can enabble loopback from DAC to ADCs, so

1.which CMPSS DAC can be loopbacked to adc?

2.which adc channel can be used to sample DAC output?

I cannot find any description in trm, thanks very much for your attention!

over 3 years ago

0 Hadi Moradisizkoohi over 3 years ago

TI__Expert 7100 points

Hi Matt,

Thanks for your patience.

1) Based on Table 14-14 in TRM, COMP DAC A can be loopbacked to ADC A and ADC C.

2) Based on Table 14-1 in TRM, A3 and C5 are internally connected to sample DAC output.

Regards,

Hadi

0 Matt Dash over 3 years ago in reply to Hadi Moradisizkoohi

Prodigy 240 points

hi, hadi,thanks for your reply. but i am still confused:

1.in 280025, i only could find CMPSSxHDAC or CMPSSxLDAC, can't find DACA signal.

2.as for VDAC connected to A3/C5, it's not DAC output, but a pin used for CMPSSxDAC reference.

is some mistake in trm? hoping for your replying. best wishes!

+1 Hadi Moradisizkoohi over 3 years ago in reply to Matt Dash

TI__Expert 7100 points

Hi Matt,

You're right...As you said A3/C5 are connected to VDAC.

In fact, DACA is used for safety checking and used in ADC. In Table 14-4 it is mentioned that "Note: Setting this bit to 1, will override the CHSEL specification for the ADC. ADC would sample COMPDACA output irrespective of the value of CHSEL". This implies that it does not use any ADC channel for this feature. Also, this feature is enabled only for CMPSS 1 and ADC A and C.

We need to document it in a better way. Thanks for bringing this to my attention.

Regards,

Hadi

0 Matt Dash over 3 years ago in reply to Hadi Moradisizkoohi

Prodigy 240 points

thank you very much, hadi. in past days, i tested this function, and the result is as your answer, this great.

0 Hadi Moradisizkoohi over 3 years ago in reply to Matt Dash

TI__Expert 7100 points

You are welcome, Matt.

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TMS320F280025C: Questions about ADCDACLOOPBACK register in Analog Subsystem