PIC18F4550 problem, Please help!!!!

[soongkhim]

HI everyone,
My sample code as follow:
TRISA=0x00;
TRISB=0x00;
TRISC=0x00;
TRISD=0x00;

PORTA=0xFF;
PORTB=0xFF;
PORTC=0xFF;
PORTD=0xFF;

I want to ask why when i measure the voltage at pin RC4, RC5 and RB5 are logic '0' ?
what is the problem?
what should i do to overcome this problem?
PLEASE HELP!!!
THANK YOU.

[ABSF]

Try "LATC=0xff;" instead of "PORTC=0xff;"

Allen

[soongkhim]

how bout RB5?

[ABSF]

how bout RB5?

ditto

[soongkhim]

HI,
using LATC and LATB still do not solve my problems.
what can i do futher?

[soongkhim]

I just noticed that port c bit 4 and 5 cannot be implemented as normal i/o. but y port b bit 5 cannot cannot be set?

[ABSF]

I just noticed that port c bit 4 and 5 cannot be implemented as normal i/o. but y port b bit 5 cannot cannot be set?

correct, RC4 & RC5 cannot be used as digital output.

Unlike other PORTC pins, RC4 and RC5 do not have
TRISC bits associated with them. As digital ports, they
can only function as digital inputs. When configured for
USB operation, the data direction is determined by the
configuration and status of the USB module at a given
time. If an external transceiver is used, RC4 and RC5
always function as inputs from the transceiver. If the
on-chip transceiver is used, the data direction is
determined by the operation being performed by the
module at that time

RB5 should be able to use as digital output unless that port pin is either open-drain or faulty. Try to connect a 10K resistor to pull it high and see if it work.

Allen

[robosang]

learn something new today, thanks

So RC4 and RC5 is actually the D+ and D- right? Yup, checked datasheet, is for USB communication

[ABSF]

learn something new today, thanks

So RC4 and RC5 is actually the D+ and D- right? Yup, checked datasheet, is for USB communication

It was new to me too until I read the datasheet. There's new things to learn everyday!

Allen

[soongkhim]

Hi,
I want to ask, why when i wan to inputting to the p18f4550, it does not work.
what should i do?
Please advice.
Thanks.

CODE: SELECT_ALL_CODE

TRISA=0x0FF;
TRISB=0x0FF;
TRISC=0x00;
TRISD=0x00;
PORTC=0x00;
PORTD=0x00;
for(;;)
{
if(PORTBbits.RB0==1)
{
PORTC++;
}
else if (PORTA!=0x00)
{
PORTD++;
}
}


when i press the button connecting between rb0 and vdd, it does not work, same as to port a.
why was it?