gnupic: Cannot get 18f252 to blink
Subject:
Cannot get 18f252 to blink
From:
David Froseth ####@####.####
Date:
24 Oct 2006 19:17:25 +0100
Message-Id: <453E58A6.8030706@umich.edu>
I am having problems getting a 18f252 to flash an LED. I am using a
PICSTART Plus with a Keyspan usb-serial adapter. I am using gpasm and
picp with OS X. This setup has worked for the 16f84a and the 16f870 chips.
I have written this simple .asm program which compiles to a .hex file
successfuly:
;Title: 0.1flash252
;File Saved As: 0.1flash252.asm
;Clock Frequency: 4 MHz
;PIC chip: 18F252
;
;Description:
;
;testing RA0 flash with 18f252;
;
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Processor type::
processor 18f252
;List file directives
list p=18f252
;SFR equates and other 18fxxx specific declarations
include "/sw/share/gputils/header/p18f252.inc"
;Configuration bytes
__config _CONFIG1H, b'00100001' ;XT oscillator
__config _CONFIG2L, b'00001110' ;enable power-up timer
__config _CONFIG2H, b'00001110' ;watchdog timer disabled
__config _CONFIG3H, b'00000001' ;CCP2 on RC1
__config _CONFIG4L, b'10000001' ;Disable LVP
;All other configuation bits involve code protection.
;Default to protection-off (logic 1)
radix dec
;;;;;;;;;;;;;;;;;;;;;;;;;;
outer_delay equ 0x20 ;First counter
inner_delay equ 0x21 ;Second counter
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
org 0x0000
goto MainLine
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;High-priority interrupt service routine:
org 0x0008
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Low-priority interrupt service routine:
org 0x0018
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Main body of the program
MainLine
;;;;;;;;;;;;;;;;;;;;;;;;
;Inits
movlw b'00000110'
movwf ADCON1 ;sets POARTA pins as digital I/O
movlw b'11111110' ;Set the RA0 pin
movwf TRISA ; to output.
movlw b'11111111'
movwf TRISB
movlw b'00000000'
movwf TRISC
;;;;;;;;;;;;;;;;;;;;;;;;
;Start
flash_led
movlw b'00000001'
xorwf PORTA,f
call debounce
goto flash_led
;;;;;;;;;;;;;;;;;;;;;;;;
;Subroutines
debounce
movlw 0xff
movwf outer_delay
load_debounce_inner_delay
movlw 0xff
movwf inner_delay
decr_debounce_loop
decfsz inner_delay,f
goto decr_debounce_loop
decfsz outer_delay,f
goto load_debounce_inner_delay
return
end
_______________________________
The .hex file is :
:020000040000FA
:040000000CEF00F011
:08001800060EC16EFE0E926E91
:10002000FF0E936E000E946E010E801A1AEC00F013
:1000300014EF00F0FF0E206EFF0E216E212E1EEF3A
:0A00400000F0202E1CEF00F012006B
:020000040030CA
:08000000FF210E0EFF0181FF3C
:00000001FF
When I read the program memory out of the chip, I get:
$ picp /dev/tty.KeySerial1 18f252 -rp
:020000040000FA
:10000000040E0060000E926E9200000E000E0000C2
:10001000010C0000000000000000000000000000D3
:10002000000000000000000E000000000020006042
:100030000000000000000000020E016C0020046EB1
:100040000000000E004000000000012E250E0020E0
:10005000002023EF00F0020026EF00F0082E24EF2E
:1000600000F0052E22EF00F0120037EF00F00150F3
:10007000806E1200FFFFFFFFFFFFFFFFFFFFFFFF8C
:10070000F9263F0C060C5B0C4F0C660C6D0C7D0C37
:10071000070C7F0C6F0C400CFFFFFFFFFFFFFFFF7C
:00000001FF
This obviously does not look the same. Is this normal? Other chips
that are working show program memory reads that are different than the
.hex file, also. I know nothing about how .hex files work.
Can anybody help me get my 18f252 to blink? What am I missing?
Thanks
