PICkit4: ICSPCLK and ISPCLK used also as analog input

Dear all,
due to space constraints I need to use also the following pins as analog inputs:
 
- RA0
- RA1
 
the analog signals are taken from an op amp output through a resistive divider as into the attached image, my question is if this type of setup may have some effect on the PICkit4 and programming perspective. The analog signals at the divider input can swing between 1V up to 4V.
 
The PIC have a 3.3V power supply voltage.
 
Pins RA0 and RA1 see an equivalent Thevenin circuit composed of a voltage generator with a voltage swing between 0.5V up to 2V in series with a 5k resistance, these voltage level and source impedance should being compatibile with the PIC ADC input module so my principal doubt is if the PICkit4 will be able to properly work and then perform the PIC programming.
 
Thanks for any hint you can let me know!
 
Best regards
F.
 

Dear @ric
during programming the analog voltage can be not equal to zero.
I've foun over the net a schematic of the PICKIT4, I don't know if this is true, but let suppose of yes, we can do some considerations about it.
 
Looking at the equivalent circuit and using the Miller theorem give the expression for the voltage at the PIC ICSP pins, then by substituting the numerical values we have:
 
VICSP_PIN=VPIKIT4*0,98+VAN*3,22*10^-3
 
so the contribute of the analog signal seems negligible regarding the one that came from the PICKIT4.
Because I think that the communication from PICKIT and PIC is bidirectional may have some transient glitch related the analog voltage when the pin change direction from input to output and output to input then this may have some inpact or not, it can be subject for some further investigation.
 
Could you please let me know what is your thinking about?
 
Thanks and best regards.
F.
 

TechDpt
I've foun over the net a schematic of the PICKIT4

Looks more like PICkit2.
 
The worst case is when the OpAmp is producing higher voltage. When you connect PICkit, and PICkit doesn't drive the programming pins, the PICkit's pulldown will tranform your voltage divider. The low resistor will become 4.7 || 10 = 3.2k. So, the voltage on Vdd will be 0.24 of the OpAmp voltage. If OpAmp goes to 5V, you'll get 1.2V, which may be Ok, even for 3.3V VDD.
 
BTW: I used similarly sized voltage divider in the design of my new programmer, except that PIC16LF1459 uses RC0 and RC1 as programming pins. Both programming pins are analog during PIC operations. IMHO, analog is very good use for programming pins. It is much better than using these pins to drive LEDs or FETs.
 

I always put a 390r resistor in series with op amp output into a2d.
 
Be careful with positive going signasl that can go above the rails.
PIC32 a2d dont have diode to +ve rail so need an external one. BAT85 is good.
I forgot and my PIC kept crashing.