Hi All,

I am hoping someone can help me interpret the P89LPC935 User Manual details in relation to the function on Pin 23.

User manual available here
http://www.standardics.nxp.com/support/d...lpc936.pdf

Pin 23 = P0.4/ CN1A/ KBI4/ DAC1/ AD13 from the LPC935 from the User Manual.

This pin has multi-functions which are turned off/on by bits in DIFFERENT sfr's.

My thinking is..........
With two functions turned-on (selected) at the same time - their function blocks are connected internally and at pin 23.

Question
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Assume: The DAC1 feature is enabled and the Comparator 1 is enabled in their respective SFRs.

Because Pin 23 CN1A =DAC1 ..... are they connected internally. This is what I am is after.(if the respective SFRs are enabled)

I want to compare a) Internal Reference set to -in:CMP1 TO b) DAC1 output (+in:CMP1) CN1A at pin23. Hence the DAC output can be calibrated against the internal reference with s/w.

My Assumption
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CN1A = DAC1 when the following SFR bits are enabled

Enable DAC1 by setting
ENADC1=1 in ADCON1 sfr turn on ADC1 block
ENDAC1 =1 in ADMODB sfr select DAC1 (instead of ADC1)

Enable Analogue Comparator 1
CE1 = 1 in CMP1 sfr Enable comparator 1
CP1 = 0 in CMP1 sfr +in Comparator 1 selects CN1A
CN1 = 0 in CMP1 sfr -in Comparator 1 selects Vref


I am hoping you can confirm my assumption with the settings above CN1A = DAC1 on pin 23.

Thanks in advance.
Joe