;; Thermomter - Copyright 2010 by Michael Kohn ;; Email: mike to mikekohn.net ;; Web: http://www.mikekohn.net/ ;; ;; Attiny2313 reading a DS18S20 temperature sensor with a 1 wire interface ;.include "tn2313def.inc" .device ATtiny2313 ; r0 = 0 ; r1 = 1 ; r2 = lower counter for waiting ; r3 = low counter for waiting ; r4 = high counter for waiting ; r5 = Read Bit value (0 or 1) / Write 255 and shift to know if it's done ; r7 = bit marker for writing .. so we know when 8 bits of the command are out ; r6 = 30 ; r8 = SREG in interrupt ; r9 = trigger a start temp ; r10 = conversion state: 0 = idle ; 1 = send_reset_pulse ; 2 = reset pulse done, ; 3 = send skip rom command (0xcc); ; 4 = wait skip rom command done ; 5 = send read command (0x44); ; 6 = wait read command done ; 7 = wait on convert done ; 8 = convert is done ; 9 = send_reset_pulse ; 10 = reset pulse done, ; 11 = send skip rom command (0xcc); ; 12 = wait skip rom command done ; 13 = send read scratchpad (0xbe) ; 14 = wait read scratchpad done ; 15 = read scratchpad ; 16 = all done ; r13 = Temp for writing hex ; r14 = Temp for reading rs232 ; r15 = 255 ; r16 = READ/WRITE low count ; r17 = Temp in main ; r18 = Temp for writing hex ; r19 = Temp for writing hex ; r20 = Temp in main ; r22 = Interrupt count ; r23 = command to send / byte read in ; r24 = response bytes ; r25 = bytes to read from scratchpad ; ; note: CLKSEL 1111 ; cycles sample rate @20 MHz ; 100 cycles per interrupt = 5us per interrupt ; ; 480us reset pulse = 96 interrupts (Sent by master) ; 60us to 240us presence pulse = 12 to 48 interrupts (Sent by DS18S20) ; 60us for a bit = 12 interrupts ; ; WRITE TIME SLOT 1: 5us low, 55us high, 1us recovery ; WRITE TIME SLOT 0: 60us low, 1us recovery ; ; READ TIME SLOT 1: 1us low, read 60us (bus is released), 1us recovery ; READ TIME SLOT 0: 1us low, read 60us (bus is held down), 1us recovery ; 1us @ 20 MHz is 20 cycles .equ RESET_PULSE = 96 .equ PRESENCE_PULSE = 48 .equ PULSE60 = 12 .macro ONE_WIRE_HIGH sbi PORTD, PD5 .endm .macro ONE_WIRE_LOW cbi PORTD, PD5 .endm .macro ONE_WIRE_OUTPUT sbi PORTD, PD5 sbi DDRD, PD5 .endm .macro ONE_WIRE_INPUT cbi DDRD, PD5 cbi PORTD, PD5 .endm .macro SKIP_ONE_WIRE_HIGH sbis PIND, PD5 .endm .macro SKIP_ONE_WIRE_LOW sbic PIND, PD5 .endm .macro PAUSE ldi r17, 2 mov r12, r17 count_r12: clr r13 count_r13: clr r14 count_r14: dec r14 brne count_r14 dec r13 brne count_r13 dec r12 brne count_r12 .endm .cseg .org 0x000 rjmp start .org 0x008 ijmp ; might as well ijmp, IJMP, go ahead and ijmp! start: ;; I'm busy. Don't interrupt me! cli ;; Set up stack ptr ;ldi r17, RAMEND>>8 ;out SPH, r17 ldi r17, RAMEND&255 out SPL, r17 ;; r0 = 0, r1 = 1, r15 = 255 eor r0, r0 eor r1, r1 inc r1 eor r15, r15 dec r15 ldi r17, 30 mov r6, r17 clr r9 ; don't force trigger clr r10 ; state = not going clr r3 clr r4 mov r2, r1 ;; Set up rs232 baud rate ldi r17, ((20000000/(16*1200))-1) >> 8 out UBRRH, r17 ldi r17, ((20000000/(16*1200))-1) & 0xff out UBRRL, r17 ; 1200 baud ;; Set up rs232 options ldi r17, (1<>8) out OCR1AH, r17 ldi r17, (99&0xff) ; compare to 100 clocks out OCR1AL, r17 ldi r17, (1<>8 ;ldi r30, ingenting&0xff ldi r31, pause_before_get_temp>>8 ldi r30, pause_before_get_temp&0xff ; Fine, I can be interrupted now sei test_mode: ldi r18, -99 test_mode_to_0: ser r17 mov r19, r18 rcall show_bcd PAUSE inc r18 brne test_mode_to_0 test_mode_to_99: clr r17 mov r19, r18 rcall show_bcd PAUSE inc r18 cpi r18, 100 brne test_mode_to_99 main: mov r20, r10 cpi r20, 2 brne not_state_2 ldi r23, 0xcc ; Skip Rom mov r7, r1 ONE_WIRE_OUTPUT ldi r29, send_char_1_wire>>8 ldi r28, send_char_1_wire&0xff movw r30, r28 inc r10 ; state = 3 rjmp main not_state_2: cpi r20, 4 brne not_state_4 ldi r23, 0x44 ; Convert T mov r7, r1 ONE_WIRE_OUTPUT ldi r29, send_char_1_wire>>8 ldi r28, send_char_1_wire&0xff movw r30, r28 inc r10 ; state = 5 rjmp main not_state_4: cpi r20, 6 brne not_state_6 ;;; DEBUG ;;;;;;;;; ;ldi r19, '>' ;;; ;rcall send_char ;;; ;mov r19, r23 ;;; ;rcall send_hex ;;; ;;; DEBUG ;;;;;;;;; clr r5 ldi r29, wait_for_convert_read_done>>8 ldi r28, wait_for_convert_read_done&0xff movw r30, r28 inc r10 ; state = 7 (wait for convert done) rjmp main not_state_6: cpi r20, 8 brne not_state_8 ;;; DEBUG ;;;;;;;;; ;ldi r19, 'R' ;;; ;rcall send_char ;;; ;;; DEBUG ;;;;;;;;; ldi r29, send_reset_pulse>>8 ldi r28, send_reset_pulse&0xff movw r30, r28 inc r10 ; state = 9 (wait for reset pulse) rjmp main not_state_8: cpi r20, 10 brne not_state_10 ldi r23, 0xcc ; Skip Rom mov r7, r1 ONE_WIRE_OUTPUT ldi r29, send_char_1_wire>>8 ldi r28, send_char_1_wire&0xff movw r30, r28 inc r10 ; state = 11 rjmp main not_state_10: cpi r20, 12 brne not_state_12 ;;; DEBUG ;;;;;;;;; ;ldi r19, '#' ;;; ;rcall send_char ;;; ;mov r19, r23 ;;; ;rcall send_hex ;;; ;;; DEBUG ;;;;;;;;; ldi r23, 0xbe ; Read scratch pad mov r7, r1 ONE_WIRE_OUTPUT ldi r29, send_char_1_wire>>8 ldi r28, send_char_1_wire&0xff movw r30, r28 inc r10 ; state = 13 (send read scratchpad) rjmp main not_state_12: cpi r20, 14 brne not_state_14 ldi r27, SRAM_START>>8 ldi r26, SRAM_START&0xff clr r7 ldi r25, 9 ldi r29, read_scratchpad>>8 ldi r28, read_scratchpad&0xff movw r30, r28 inc r10 ; state = 15 (read scratchpad) rjmp main not_state_14: cpi r20, 16 brne not_state_16 ldi r29, pause_before_get_temp>>8 ldi r28, pause_before_get_temp&0xff movw r30, r28 ;ldi r19, '|' ;rcall send_char ldi r27, SRAM_START>>8 ldi r26, SRAM_START&0xff ldi r25, 10 dump_mem: ld r19, X+ ;rcall send_hex rcall send_char dec r25 brne dump_mem lds r17, SRAM_START+2 lds r19, SRAM_START+1 clc ror r17 ror r19 rcall show_bcd clr r10 ; state = 0 (idle) rjmp main not_state_16: tst r9 brne start_temp in r20, UCSRA ; poll uart to see if there is a data waiting sbrs r20, RXC rjmp main ; if no data, loop around in r19, UDR ; read from serial tst r10 ; if (state != 0 || c != 't') { echo and ignore } brne no_start_temp cpi r19, 't' brne no_start_temp start_temp: clr r9 rcall memset mov r10, r1 ; state = 1 ;; Atomic BOOM! ldi r29, send_reset_pulse>>8 ldi r28, send_reset_pulse&0xff movw r30, r28 rjmp main no_start_temp: ;rcall send_char ; echo for debug rjmp main ;; show_bcd(r17, r19) - shows r19 in the bcd display. r17 is negative flags show_bcd: tst r17 breq not_neg cbi PORTD, PD4 neg r19 rjmp do_bcd not_neg: sbi PORTD, PD4 do_bcd: clr r17 slow_loser_div: cpi r19, 10 brlo done_with_div inc r17 subi r19, 10 rjmp slow_loser_div done_with_div: swap r17 or r19, r17 out PORTB, r19 ret ingenting: reti memset: ldi r27, SRAM_START>>8 ldi r26, SRAM_START&0xff ldi r19, 10 memset_again: st X+, r0 dec r19 brne memset_again ret ;; Set reset pulse pin low send_reset_pulse: in r8, SREG ONE_WIRE_OUTPUT ONE_WIRE_LOW ldi r31, reset_state>>8 ldi r30, reset_state&0xff ldi r22, RESET_PULSE out SREG, r8 reti ;; Keep reset pulse low for 480us reset_state: in r8, SREG dec r22 brne reset_state_continue ldi r31, wait_presence_pulse>>8 ldi r30, wait_presence_pulse&0xff ldi r22, PRESENCE_PULSE ONE_WIRE_INPUT ; 1-wire is now input reset_state_continue: out SREG, r8 reti ;; Wait for line to go low by the DS18S20, so we know the chip answers wait_presence_pulse: in r8, SREG SKIP_ONE_WIRE_LOW rjmp exit_wait_presence_pulse ldi r31, presence_pulse_start>>8 ldi r30, presence_pulse_start&0xff exit_wait_presence_pulse: out SREG, r8 reti ;; Wait for presence pulse to end presence_pulse_start: in r8, SREG SKIP_ONE_WIRE_LOW rjmp present_now dec r22 breq cant_find_presence out SREG, r8 reti cant_find_presence: ldi r31, ingenting>>8 ldi r30, ingenting&0xff clr r10 out SREG, r8 reti present_now: ldi r31, ingenting>>8 ldi r30, ingenting&0xff ONE_WIRE_OUTPUT ; 1 wire idle mov r23, r22 ; FIXME - DEBUG ;rcall send_hex inc r10 ; state = 2 out SREG, r8 reti ; void send_char(r19) : r14 trashed send_char: in r14, UCSRA ; check to see if it's okay to send a char sbrs r14, UDRE rjmp send_char ; if it's not okay, loop around :) out UDR, r19 ; output a char over rs232 ret ; void send_nibble(r19) : r14, r18 trashed send_nibble: cpi r19, 10 brlo hex_nibble_under_10 subi r19, 10 ldi r18, 'A' add r19, r18 rcall send_char ret hex_nibble_under_10: ldi r18, '0' add r19, r18 rcall send_char ret ; void send_hex(r19) : r13, r14, r18 trashed send_hex: mov r13, r19 swap r19 andi r19, 0x0f rcall send_nibble mov r19, r13 andi r19, 0x0f rcall send_nibble ldi r19, ' ' rcall send_char ret send_char_1_wire: in r8, SREG tst r7 ; if (r7 == 0) { done with this byte } brne bang_next_bit ldi r31, ingenting>>8 ldi r30, ingenting&0xff inc r10 ; state = 4, 8 out SREG, r8 reti bang_next_bit: ldi r22, PULSE60 lsl r7 ONE_WIRE_LOW ;ldi r29, send_char_1_wire>>8 ;ldi r28, send_char_1_wire&0xff sbrc r23, 0 rjmp command_bit_set ;;;;;;;;; ;ldi r19, '0' ;rcall send_char ;;;;;;;;; ldi r31, write_zero>>8 ldi r30, write_zero&0xff lsr r23 out SREG, r8 reti command_bit_set: ;;;;;;;;; ;ldi r19, '1' ;rcall send_char ;;;;;;;;; ldi r31, write_one>>8 ldi r30, write_one&0xff lsr r23 out SREG, r8 reti ;; Wait for a READ ZERO from the chip so we know the convert is done wait_for_convert: ONE_WIRE_OUTPUT ONE_WIRE_LOW ldi r29, wait_for_convert_read_done>>8 ldi r28, wait_for_convert_read_done&0xff ldi r31, read_start>>8 ldi r30, read_start&0xff out SREG, r8 reti wait_for_convert_read_done: in r8, SREG ONE_WIRE_OUTPUT tst r5 breq wait_for_convert ldi r31, ingenting>>8 ldi r30, ingenting&0xff inc r10 ; state = 6 out SREG, r8 reti read_scratchpad: in r8, SREG ONE_WIRE_OUTPUT ;;;;;;;;;;; ;mov r19, r5 ;rcall send_hex ;;;;;;;;;;; lsr r23 sbrc r5, 0 sbr r23, 128 ;sbrs r5, 0 ;cbr r23, 7 tst r7 brne read_next_bit ;;;;;;;;;;; ;mov r19, r23 ;rcall send_hex ;;;;;;;;;;; st X+, r23 mov r7, r1 tst r25 breq read_scratchpad_done dec r25 read_next_bit: ONE_WIRE_LOW lsl r7 ;clr r16 ldi r29, read_scratchpad>>8 ldi r28, read_scratchpad&0xff ldi r31, read_start>>8 ldi r30, read_start&0xff out SREG, r8 reti read_scratchpad_done: ONE_WIRE_OUTPUT ldi r31, ingenting>>8 ldi r30, ingenting&0xff inc r10 ; state = 10 out SREG, r8 reti write_one: in r8, SREG ONE_WIRE_HIGH dec r22 brne write_one_exit_int ;movw r30, r28 ldi r31, send_char_1_wire>>8 ldi r30, send_char_1_wire&0xff write_one_exit_int: out SREG, r8 reti write_zero: in r8, SREG dec r22 brne write_zero_exit_int ONE_WIRE_HIGH ;movw r30, r28 ldi r31, send_char_1_wire>>8 ldi r30, send_char_1_wire&0xff write_zero_exit_int: out SREG, r8 reti read_start: in r8, SREG ONE_WIRE_INPUT clr r16 ldi r31, read_bit>>8 ldi r30, read_bit&0xff ldi r22, PULSE60 out SREG, r8 reti read_bit: in r8, SREG SKIP_ONE_WIRE_HIGH ; sbis PIN, BIT inc r16 ; inc r16 if one wire is low dec r22 brne read_bit_exit ;cpi r16, (PULSE60-4) ;brlo read_a_zero ONE_WIRE_OUTPUT ;mov r19, r16 ;rcall send_hex tst r16 brne read_a_zero mov r5, r1 movw r30, r28 out SREG, r8 reti read_a_zero: clr r5 movw r30, r28 read_bit_exit: out SREG, r8 reti pause_before_get_temp: in r8, SREG inc r3 brne leave_pause inc r4 brne leave_pause dec r2 brne leave_pause mov r2, r6 mov r9, r1 leave_pause: out SREG, r8 reti signature: .db "Thermometer - Copyright 2010 - Michael Kohn - Version 0.02",0,0