What is an ADC "active channel" on a Tiny45?

Go To Last Post
3 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

From the Tiny45 RevG datasheet (still unlocked):

Quote:
• Bit 7:6,4 – REFS2:REFS0: Voltage Reference Selection Bits

These bits select the voltage reference (VREF) for the ADC, as shown in Table 20-2. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set). Whenever these bits are changed, the next conversion will take 25 ADC clock cycles. If active channels are used, using VCC or an external AREF higher than (VCC - 1V) as a voltage reference is not recommended, as this will affect the ADC accuracy.

Any guesses on what an "active channel" is? Fast-changing signal?

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Nobody with help for theusch? I'll try...
I think active=differential channels in this moment, look at ADC characteristics for differential channels in tiny24 datasheet, when conditions are Aref=4V Vcc=5V in opposite to Single ended channels 5V/5V. But this is my theory only.
BTW here is more mystery in ADMUX in this locked datasheet.
Szymon

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

or when 20x gain is used ?