Temp Meter

the on-chip temperature sensor
The '51 does not have any such thing, you need to specify the actual derivative.

Need assistance in C or assembler ...
does that translate to "send me the code?". Sounds like that when nothing else is said.

Erik

the on-chip temperature sensor
The '51 does not have any such thing, you need to specify the actual derivative.

Need assistance in C or assembler ...
does that translate to "send me the code?". Sounds like that when nothing else is said.

Erik

; Temp_2.ASM
; This program configures the on-chip temperature sensor with the ADC.
; An external 18.432MHz crystal is used as the system clock source.
; The ADC is configured for left-justified mode, GAIN = 2, using Timer3 overflows
; as the start-of-conversion source.
; Timer3 is configured in auto-reload mode to overflow every 10ms.
; The ADC conversion complete interrupt handler reads the ADC value and compares it
; Tmp = (about 25 degrees C), stored in ROOMCODE.
; If the measured Tmp is below this value, the LED is turned off.
; If the measured value is above ROOMCODE, the LED is turned on.
; The LED switch point value - ROOMCODE.
;
; EQUATES
$INCLUDE (C8051F000.inc)
LED EQU P1.6 ;LED on target board ('1' is LED ON)
SYSCLK EQU 18432 ;SYSCLK frequency in kHz
TC_10ms EQU (SYSCLK / 12) * 10 ;number of timer counts in 10ms
ROOMCODE EQU 0xb3f0 ;left-justified ADC value for 25 degrees C.
;
; VARIABLES
;
MYDATA SEGMENT DATA ; declare DATA segment
RSEG MYDATA ; select DATA segment
; ADC data variables
TEMPCODE: DS 2 ; holding register for temp code (16-bit)
; stored MSB-first
;
; STACK

STACK SEGMENT IDATA ; declare STACK segment
RSEG STACK
DS 80h ; reserve 128 bytes for stack
;
; MACRO DEFINITIONS
; RESET AND INTERRUPT VECTOR TABLE
;
CSEG AT 0
ljmp Main
org 7bh
ljmp ADC0_ISR ; ADC0 end of conversion interrupt

; MAIN PROGRAM CODE
;
Temp_2 SEGMENT CODE ; declare CODE segment
RSEG Temp_2 ; select CODE segment
USING 0 ; using register bank 0
Main:
mov WDTCN, #0deh ; disable watchdog timer
mov WDTCN, #0adh
mov SP, #STACK-1 ; init stack pointer
mov OSCXCN, #67h ; enable external crystal oscillator at 18.432MHz
clr A ; wait at least 1ms
djnz acc, $ ; wait 512us
djnz acc, $ ; wait 512us
osc_wait: ; poll for XTLVLD-->1
mov a, OSCXCN
jnb acc.7, osc_wait

orl OSCICN, #08h ; select external oscillator as
; system clock source
orl OSCXCN, #80h ; enable missing clock detector
mov XBR2, #40h ; Enable crossbar and weak pull-ups
orl PRT1CF, #40h ; enable P1.6 (LED on target board) as push-pull
acall ADC0_Init ; initialize ADC0 and temp sensor
acall Timer3_Init ; initialize Timer3
acall Timer3_Start ; enable Timer3
acall ADC0_Enable ; enable ADC
setb EA ; enable global interrupts
sjmp $ ; spin forever
; MAIN SUBROUTINES;
; INTERRUPT VECTORS
;
; ADC0_ISR
;
; ISR is activated on the completion of an ADC sample.
; When event occurs, the ADC value is copied to the holding variable TEMPCODE, and is
; compared with the code for 25 degrees C.
; If the temperature is above 25 degrees C, the LED is turned on.
; If the temperature is below 25 degrees C, the LED is turned off.
; There is no correction for self-heating.
;
ADC0_ISR:
push PSW ; preserve registers
push acc
clr ADCINT ; clear ADC0 interrupt flag
mov TEMPCODE, ADC0H ; copy MSB of ADC0 result into
; TEMPCODE
mov TEMPCODE+1, ADC0L ; copy LSB of ADC result into
; TEMPCODE

; compare TEMPCODE with value expected for 25 degrees C
; if (TEMPCODE - ROOMDEG) < 0, then turn LED off, otherwise, turn it on.
; calculate TEMPCODE - ROOMREG and store in TEMPCODE (16-bit subtract)

clr C
mov a, TEMPCODE+1 ; subtract LSBs
subb a, #LOW(ROOMCODE)
mov TEMPCODE+1, a ; store new LSB
mov a, TEMPCODE ; subtract MSBs (and carry)
subb a, #HIGH(ROOMCODE)
mov TEMPCODE,a ; store new MSB
setb LED ; turn LED on.
jnc ADC0_ISR_END ; exit if subtract result was positive,
clr LED ; otherwise, turn LED off then exit
ADC0_ISR_END:
pop acc
pop PSW

reti

;

; SUBROUTINES
;-
; Timer3_Init
;
; Routine initializes Timer3 in 16-bit auto-reload mode to overflow
; at 100Hz using SYSCLK/12 as its time base. Exits with Timer3
; stopped and Timer3 interrupts disabled.
;
Timer3_Init:
mov TMR3CN, #00h ; stop Timer3, clear TF3, use
; SYSCLK/12 as timebase
mov TMR3RLH, #HIGH(-TC_10ms); init reload values
mov TMR3RLL, #LOW(-TC_10ms)
mov TMR3H, #0ffh ; set to auto-reload immediately
mov TMR3L, #0ffh
anl EIE2, #NOT(01h) ; disable Timer3 interrupts
ret
;
; TIMER3_Start
; This routine starts Timer3
;
Timer3_Start:
orl TMR3CN, #04h ; set TR3
ret
;
; Initialize ADC0 for left-justified mode monitoring the
; on-chip temp sensor at a gain of '2'. Leaves ADC in disabled state.

ADC0_Init:
clr ADCEN ; disable ADC
mov REF0CN, #07h ; enable temp sensor, bias
; generator, and output
; buffer
mov AMX0SL, #0fh ; select TEMP sensor as ADC0
; input
mov ADC0CF, #80h ; set SAR clock to SYSCLK/16
orl ADC0CF, #01h ; PGA Gain = 2
mov ADC0CN, #45h ; ADC disabled, low power
; track mode, ADC0 conversions
; initiated by overflow on
; Timer3, left-justified data
ret
;
; This routine enables the ADC and ADC interrupts.
ADC0_Enable:
setb ADCEN ; enable ADC
orl EIE2, #02h ; enable ADC EOC interrupt
ret;
; End of file.
END