; MODIFIED BY TERRY COTTON ZS1AYJ TO ALLOW ASSEMBLY ; USING ATMEL AVR STUDIO. ; Copyright (C) 2000 Jesper Hansen . ; ; 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 is written for use with AVR-GCC in assembler mode ; flag: -x assembler-with-cpp ; ; ; 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 ;****************************************************************************** #include "2313def.inc" ; .section .text .org 0 rjmp RESET .org 14 rjmp RX_COMPLETE_INT ;****************************************************************************** ; data tables ;****************************************************************************** ; force table to begin at 256 byte boundary .org 0x80 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 ;****************************************************************************** ; code ;****************************************************************************** RESET: ldi r16, RAMEND out SPL, r16 ; setup stack pointer ; Following calculation uses 11059 KHz crystal ; BAUD = fosc / 16(UBRR+1) ; UBBR = (fosc/16*BAUD)-1 (35.999 - 1) ; UBBR = 35 (0x23) ldi r16,0x023 ; set uart speed to 19.2 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 r31,1 ; setup Z pointer hi ldi r30,0 ; setup Z pointer lo ; clear accumulator ldi r29,0x00 ; clear accumulator ldi r28,0x00 ; clear accumulator ; setup adder registers ldi r24,0x55 ; 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 r31,1 ; setup Z pointer hi ldi r30,0 ; setup Z pointer lo rjmp tx_exit tx_10: cpi r16,'2' ; request sawtooth output brne tx_11 ldi r31,2 ; setup Z pointer hi ldi r30,0 ; setup Z pointer lo rjmp tx_exit tx_11: cpi r16,'3' ; request triangle output brne tx_12 ldi r31,3 ; setup Z pointer hi ldi r30,0 ; setup Z pointer lo rjmp tx_exit tx_12: cpi r16,'4' ; request squarewave output brne tx_13 ldi r31,4 ; setup Z pointer hi ldi r30,0 ; 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 ;****************************************************************************** ; end of file ;******************************************************************************