Need Help (Can't used AN8 and AN10 on SK40C)

[hafiz99]

Hello To all Pros i cant used AN8 and AN10 using PIC18F4580 with SK40C Because of SW1(RB0) and SW2(RB1) this circuit switch circuit let the current flow into PIC when switch is Open. =.=

Why they Design like this??? how to used AN connection like this????
The Port B0 and B1 already have 4.71v =.=

Can someone help me because i need to used 10 Analog input

[ABSF]

The SK40C was originally designed for 16F877A and later some of the low end 18F PIC chips were also taking advantage of it. Maybe its time for Cytron to come out with SK40D that would have all the switches and LED which can be deselected by jumpers.

The easiest way to solve your problem is to remove R5 and R6 (10K resistors) next to the UART socket location. But then the SW1 and SW2 on RB0 and RB1 would not function anymore.

I was also surprised to see that there was no diode in series with the resistor connected to MCLR as in the schematics. The manual was V1.2 DEC 2010.

Allen

[kl84]

i cant used AN8 and AN10 using PIC18F4580 with SK40C Because of SW1(RB0) and SW2(RB1) this circuit switch circuit let the current flow into PIC when switch is Open. =.=

Why they Design like this??? how to used AN connection like this????
The Port B0 and B1 already have 4.71v =.=

I guess they have no choice but to give up some pins for the basic circuit like switch and led. Afaik PORTD is reserved for LCD. For PIC16F877A, RB0 and RB1 don't have AN function. For PIC18F4550, out of all the I/O pins only analog has the most pins available and I've never use up to 10 analog pins before. Usually less than 5 AN pins are used. Haha...may be you are that 1% (or less?) who used up to 10 AN pins. If they choose other pins for switch and led, they will receive my complain then

Can someone help me because i need to used 10 Analog input

Do as ABSF suggested or cut off the track and connect it to other pin you wish to use.

Maybe its time for Cytron to come out with SK40D that would have all the switches and LED able to be deselected by jumpers.

Good idea...

[robosang]

Yup, most of old PIC does not have more than 8 channel of ADC. I guess why they use RB0 and RB1 as switch input might because the INT0 and INT1 is located there, that is external interrupt Of course they will need to choose some of the pin to use as switch and LED as basic input and output, else it will not be basic board , it will become a breakout board!

Nonetheless, Allen suggestion is good. Maybe a selector to enable and disable the switches and LEDs connection, just like what they did for Vusb and LCD backlight?

Yup, notice they din put diode at MCLR pin, I guess the resistor is big enough to clamp the voltage during programming.