?? minidds.asm
字號:
;
; Copyright (C) 2000 Jesper Hansen <jesperh@telia.com>.
;
; This program is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation; either version 2
; of the License, or (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, write to the Free Software Foundation,
; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
;
;
;*******************************************************************
;*******************************************************************
;
;Description
;
; Poor-mans DDS Synthesizer
;
; Author = Jesper Hansen
; Target = AT90S2313
; Date = 2001-02-15
;
; Code originally written for use with AVR-GCC in assembler mode
;
; Modified for the Atmel AVR assembler by:
;
; Leon Heller (leon_heller@hotmail.com)
; Date 4/10/02
;
; PB0..7 = D/A Data out
;
; PD0 RXD
; PD1 TXD
; PD2..6 not used
;
;*******************************************************************
;*******************************************************************
;
;
;
; Output frequency (using 24 bit accumulator) :
;
; f = deltaPhase * fClock/2^24
;
; fClock is in this case the CPU clock divided by the
; number of cycles to output the data ( 9 cycles )
;
; f = r24/r25/r26 * (11059200/9)/16777216
;
; f = r24/r25/r26 * 0.073242188
;
; fMax (theoretical) = 0.5 * fClock
;
;******************************************************************************
; start of code
;******************************************************************************
.nolist
.include "2313def.inc"
.list
.cseg
.org 0
rjmp RESET
.org 7
rjmp RX_COMPLETE_INT
;******************************************************************************
; code
;******************************************************************************
RESET:
ldi r16, RAMEND
out SPL, r16 ; setup stack pointer
ldi r16,5 ; set uart speed to 115 kbps
out UBRR,r16
ldi r16,0x98 ; enable RXint and enable tx/rx
out UCR,r16
sei ; global enable interrupts
ser r16 ;
out DDRB,r16 ; set all PORTB bits as output
; set sinewave output as default
ldi ZH,high(2*sine) ; setup Z pointer hi
ldi ZL,low(2*sine) ; setup Z pointer lo
; clear accumulator
ldi r29,0x00 ; clear accumulator
ldi r28,0x00 ; clear accumulator
; setup adder registers
ldi r24,0x56 ; setup adder value
ldi r25,0x35 ; to 1 kHz
ldi r26,0x00 ;
; main loop
;
; r28,r29,r30 is the phase accumulator
; r24,r25,r26 is the adder value determining frequency
;
; add value to accumulator
; load byte from current table in ROM
; output byte to port
; repeat
;
LOOP1:
add r28,r24 ; 1
adc r29,r25 ; 1
adc r30,r26 ; 1
lpm ; 3
out PORTB,r0 ; 1
rjmp LOOP1 ; 2 => 9 cycles
;**********************************************************************
; communication functionality
;**********************************************************************
;
; get char in r16
;
get_char:
in r16,USR ; wait for a byte to be ready
sbrs r16,7 ; ready ?
rjmp get_char ; no, wait some more
in r16,UDR ; get the byte
ret ; and return
;
; send char in r16
;
send_char:
push r16 ; save r16
send_c2:
in r16,USR ; wait for the transmitter to be ready
sbrs r16,5 ; ready ?
rjmp send_c2 ; no, wait some more
pop r16 ; restore r16
out UDR,r16 ; send char
ret ; ans return
;
; send the current frequency to the PC
; as a 5 byte sequence :
; 'F' folowed by a 32 bit phase accumulator value
;
;
send_data:
push r16 ; save r16
ldi r16,'F' ; flag
rcall send_char
clr r16 ; zero byte for 32-bit compatibility
rcall send_char ; MSB
mov r16,r26
rcall send_char ; high add
mov r16,r25
rcall send_char ; mid add
mov r16,r24
rcall send_char ; low add
ldi r16,0x0a
rcall send_char ; terminator
pop r16
ret
; add 1 to the phase accumulator
up_one:
adiw r24,1
clr r23
adc r26,r23
ret
; add 10 to the phase accumulator
up_ten:
adiw r24,10
clr r23
adc r26,r23
ret
; add 100 to the phase accumulator
up_hundred:
ldi r23,0x64
add r24,r23
clr r23
adc r25,r23
adc r26,r23
ret
; subtract 1 from the phase accumulator
down_one:
sbiw r24,1
clr r23
sbc r26,r23
ret
; subtract 10 from the phase accumulator
down_ten:
sbiw r24,10
clr r23
sbc r26,r23
ret
; subtract 100 from the phase accumulator
down_hundred:
clr r23
subi r24,0x64
sbc r25,r23
sbc r26,r23
ret
;
; read in 4 characters from the serial link
;
read_4:
rcall get_char ; read and ignore bits 32..24
rcall get_char ; read bits 23..16
mov r26,r16
rcall get_char ; read bits 15..8
mov r25,r16
rcall get_char ; read bits 7..0
mov r24,r16
ret
;
; Interrupt routine for incoming bytes on the RS232 link
;
RX_COMPLETE_INT:
push r16
in r16,UDR
cpi r16,'+' ; up one
brne tx_2
rcall up_one
rjmp tx_exit
tx_2:
cpi r16,'u' ; up ten
brne tx_3
rcall up_ten
rjmp tx_exit
tx_3:
cpi r16,'U' ; up hundred
brne tx_4
rcall up_hundred
rjmp tx_exit
tx_4:
cpi r16,'-' ; down one
brne tx_5
rcall down_one
rjmp tx_exit
tx_5:
cpi r16,'d' ; down ten
brne tx_6
rcall down_ten
rjmp tx_exit
tx_6:
cpi r16,'D' ; down hundred
brne tx_7
rcall down_hundred
rjmp tx_exit
tx_7:
cpi r16,'s' ; frequency setting
brne tx_8
rcall read_4
rjmp tx_exit
tx_8:
cpi r16,'?' ; just force a reply
brne tx_9
rjmp tx_exit
tx_9:
cpi r16,'1' ; request sinewave output
brne tx_10
ldi r31,high(2*sine) ; setup Z pointer hi
ldi r30,low(2*sine) ; setup Z pointer lo
rjmp tx_exit
tx_10:
cpi r16,'2' ; request sawtooth output
brne tx_11
ldi r31,high(2*sawtooth) ; setup Z pointer hi
ldi r30,low(2*sawtooth) ; setup Z pointer lo
rjmp tx_exit
tx_11:
cpi r16,'3' ; request triangle output
brne tx_12
ldi r31,high(2*triangle) ; setup Z pointer hi
ldi r30,low(2*triangle) ; setup Z pointer lo
rjmp tx_exit
tx_12:
cpi r16,'4' ; request squarewave output
brne tx_13
ldi r31,high(2*square) ; setup Z pointer hi
ldi r30,low(2*square) ; setup Z pointer lo
rjmp tx_exit
; unknown command, just ignore it
tx_13:
; always reply with the current frequency
tx_exit:
rcall send_data
pop r16
reti
;******************************************************************************
; data tables
;******************************************************************************
; force table to begin at 256 byte boundary
.org 0x200
sine: ; 256 step sinewave table
.db 0x80,0x83,0x86,0x89,0x8c,0x8f,0x92,0x95,0x98,0x9c,0x9f,0xa2,0xa5,0xa8,0xab,0xae
.db 0xb0,0xb3,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,0xc9,0xcc,0xce,0xd1,0xd3,0xd5,0xd8
.db 0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xed,0xef,0xf0,0xf2,0xf3,0xf5
.db 0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,0xfe,0xfe,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xfe,0xfe,0xfd,0xfc,0xfc,0xfb,0xfa,0xf9,0xf8,0xf7
.db 0xf6,0xf5,0xf3,0xf2,0xf0,0xef,0xed,0xec,0xea,0xe8,0xe6,0xe4,0xe2,0xe0,0xde,0xdc
.db 0xda,0xd8,0xd5,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,0xc4,0xc1,0xbf,0xbc,0xb9,0xb6,0xb3
.db 0xb0,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x98,0x95,0x92,0x8f,0x8c,0x89,0x86,0x83
.db 0x80,0x7c,0x79,0x76,0x73,0x70,0x6d,0x6a,0x67,0x63,0x60,0x5d,0x5a,0x57,0x54,0x51
.db 0x4f,0x4c,0x49,0x46,0x43,0x40,0x3e,0x3b,0x38,0x36,0x33,0x31,0x2e,0x2c,0x2a,0x27
.db 0x25,0x23,0x21,0x1f,0x1d,0x1b,0x19,0x17,0x15,0x13,0x12,0x10,0x0f,0x0d,0x0c,0x0a
.db 0x09,0x08,0x07,0x06,0x05,0x04,0x03,0x03,0x02,0x01,0x01,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x02,0x03,0x03,0x04,0x05,0x06,0x07,0x08
.db 0x09,0x0a,0x0c,0x0d,0x0f,0x10,0x12,0x13,0x15,0x17,0x19,0x1b,0x1d,0x1f,0x21,0x23
.db 0x25,0x27,0x2a,0x2c,0x2e,0x31,0x33,0x36,0x38,0x3b,0x3e,0x40,0x43,0x46,0x49,0x4c
.db 0x4f,0x51,0x54,0x57,0x5a,0x5d,0x60,0x63,0x67,0x6a,0x6d,0x70,0x73,0x76,0x79,0x7c
sawtooth: ; 256 step sawtoothwave table
.db 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f
.db 0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f
.db 0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28,0x29,0x2a,0x2b,0x2c,0x2d,0x2e,0x2f
.db 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x3a,0x3b,0x3c,0x3d,0x3e,0x3f
.db 0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f
.db 0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f
.db 0x60,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x6b,0x6c,0x6d,0x6e,0x6f
.db 0x70,0x71,0x72,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x7b,0x7c,0x7d,0x7e,0x7f
.db 0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87,0x88,0x89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f
.db 0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f
.db 0xa0,0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xab,0xac,0xad,0xae,0xaf
.db 0xb0,0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xbb,0xbc,0xbd,0xbe,0xbf
.db 0xc0,0xc1,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xcb,0xcc,0xcd,0xce,0xcf
.db 0xd0,0xd1,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xdb,0xdc,0xdd,0xde,0xdf
.db 0xe0,0xe1,0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xeb,0xec,0xed,0xee,0xef
.db 0xf0,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfe,0xff
triangle: ; 256 step trianglewave table
.db 0x00,0x02,0x04,0x06,0x08,0x0a,0x0c,0x0e,0x10,0x12,0x14,0x16,0x18,0x1a,0x1c,0x1e
.db 0x20,0x22,0x24,0x26,0x28,0x2a,0x2c,0x2e,0x30,0x32,0x34,0x36,0x38,0x3a,0x3c,0x3e
.db 0x40,0x42,0x44,0x46,0x48,0x4a,0x4c,0x4e,0x50,0x52,0x54,0x56,0x58,0x5a,0x5c,0x5e
.db 0x60,0x62,0x64,0x66,0x68,0x6a,0x6c,0x6e,0x70,0x72,0x74,0x76,0x78,0x7a,0x7c,0x7e
.db 0x80,0x82,0x84,0x86,0x88,0x8a,0x8c,0x8e,0x90,0x92,0x94,0x96,0x98,0x9a,0x9c,0x9e
.db 0xa0,0xa2,0xa4,0xa6,0xa8,0xaa,0xac,0xae,0xb0,0xb2,0xb4,0xb6,0xb8,0xba,0xbc,0xbe
.db 0xc0,0xc2,0xc4,0xc6,0xc8,0xca,0xcc,0xce,0xd0,0xd2,0xd4,0xd6,0xd8,0xda,0xdc,0xde
.db 0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xee,0xf0,0xf2,0xf4,0xf6,0xf8,0xfa,0xfc,0xfe
.db 0xff,0xfd,0xfb,0xf9,0xf7,0xf5,0xf3,0xf1,0xef,0xef,0xeb,0xe9,0xe7,0xe5,0xe3,0xe1
.db 0xdf,0xdd,0xdb,0xd9,0xd7,0xd5,0xd3,0xd1,0xcf,0xcf,0xcb,0xc9,0xc7,0xc5,0xc3,0xc1
.db 0xbf,0xbd,0xbb,0xb9,0xb7,0xb5,0xb3,0xb1,0xaf,0xaf,0xab,0xa9,0xa7,0xa5,0xa3,0xa1
.db 0x9f,0x9d,0x9b,0x99,0x97,0x95,0x93,0x91,0x8f,0x8f,0x8b,0x89,0x87,0x85,0x83,0x81
.db 0x7f,0x7d,0x7b,0x79,0x77,0x75,0x73,0x71,0x6f,0x6f,0x6b,0x69,0x67,0x65,0x63,0x61
.db 0x5f,0x5d,0x5b,0x59,0x57,0x55,0x53,0x51,0x4f,0x4f,0x4b,0x49,0x47,0x45,0x43,0x41
.db 0x3f,0x3d,0x3b,0x39,0x37,0x35,0x33,0x31,0x2f,0x2f,0x2b,0x29,0x27,0x25,0x23,0x21
.db 0x1f,0x1d,0x1b,0x19,0x17,0x15,0x13,0x11,0x0f,0x0f,0x0b,0x09,0x07,0x05,0x03,0x01
square: ; 256 step squarewave table
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
.db 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
;******************************************************************************
; end of file
;******************************************************************************
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