18f4550-problem output

[MINHLE]

thank for ur words.

i did try bare pic18f4550, it runs well, and letters moving smothly. but when i add 595 shift register, the output is double and uncontrolable i.e. letter a, the result is 2 a,

the thinh that i make some change in the .inc file. it does not solve the problem. st wrong in my program. i tried to narrow down the problem. then see that the issue comes from the scan subroutine (tried it by directing pic18f to control the matrix display (without 595) i.e clear scan port after each scanning). but in this program i cannot.

note that the program runs well with pic16f877a and other pic16f's
regards,

[Normnet]

MINHLE

From the 18F4550 data sheet:
Digital input RC5 and RC4 are only available as port pins
when the USB module is disabled (UCON<3> = 0).

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.


Norm

[MINHLE]

thanks Norm,
i see it now, but in the program portC does not service. (PORTB.0,1,2 FOR DATA, LATCH AND CLK)
after several tests, i found that problem comes from peekcode.
direct input data to the 595, output is ok. but when i read data from flash memory by PEEKCODE, the problem appears.

READING data from flash memory - BYTE
WRITING data to flash memory - WORD

I attempted to isolate lower byte of data (word) reading from flash memory, it does not solve the issue

(note that changing osc configuration in the .inc does not effect the result)

in the section 5.6 (PBP REERENCE MANUAL) concerning POKECODE

"Note that POKECODE is a specialized command intended for use in
circumstances under which standard methods won't serve. LOOKUP
and LOOKUP2 are usually a better choice for constructing lookup
tables in code space"
REGARDS