;********************************************************************
; Authors       : Tomer Gross - 322712753, Yaniv Korobkin - 207329525
; Date          : 14 on January, 2020
; File          : voltmeter_project.asm
; Description   : sample the voltage of the analog signal and send it through the uart
                ; every time that 'M' pressed
;********************************************************************
#include<ADUC841.H>

BSEG  ; define flags
    ADC_FLAG: DBIT 0  ; set when adc done sample
    TI_FLAG: DBIT 0  ; set when TI is set
    RI_FLAG: DBIT 0  ; set when we received 'M'

CSEG AT 00h
    JMP START

CSEG AT 23h  ; serial ISR
    JMP CHECK_INPUT

CSEG AT 33H  ; adc ISR
    SETB ADC_FLAG
RETI


CSEG AT 0100H
;______________________________________________________________________________
                                                    ; SERIAL INTERRUPT HANDLING

; in addition to prevent ovarlapping we handling the serial interrupt outside of the ISR
CHECK_INPUT:
    JBC TI, DONE_TRANSMITTING  ; if done transmiting then jump and clear TI

    CHECK:
        MOV R1, SBUF  ; get the pressed key's ASCII value
        CJNE R1, #'M', NOT_M_ME  ; in the case which the pressed key isnt 'M'
        SETB RI_FLAG
        JMP NOT_M  ; we need to clear TI&RI anyway to prevent redundent call for the interrupt service routine

    DONE_TRANSMITTING:
    SETB TI_FLAG  ; set to alert that a new character can be trasmitting

    NOT_M_ME:
    JMP INVALID_INPUT
    RETI

    NOT_M:
    CLR RI
    RETI
;____________________________________________________________________
                                                    ; MAIN PROGRAM
START:
    ; set UART
    ; puts the UART in 8-bit variable baud rate mode
    CLR SM0
    SETB SM1
    SETB REN  ;allow recieved signals

    ; setting timer 3
    ANL T3CON, #11111010B ; bit7 = enable bit, reserving bits 6-3, we allow only mode 010 (DIV=2)
    ORL T3CON, #10000010B ; bit7 = enables Timer 3 to provide the clock to the UART, bits 2-0: DIV = 2 = 010
    MOV T3FD, #32 ; baud-rate=115200bps according to formulas (as shown in the documentations)

    ; ADC setup
    MOV ADCCON1, #10111000B ; bit7 = adc mode is on, bit6 = disable external vref (as default its 2.5[v] - as we want), reserving bits 5-3, disable 3 last bits
    MOV ADCCON2, #00000000B ; we want to ensure that adc2 isnt working

    SETB ES  ; allow serial interrupts
    SETB EADC  ; allow adc interrupts
    SETB EA  ; allow global interrupts (should be last!)


POLLING:
    ; busy wait  - release when we receive 'M'
    JNB RI_FLAG, $
    CLR RI_FLAG  ; allow to get more 'M's

;____________________________________________________________________
                                                    ; SUBROUTINES
SAMPLE:
    PUSH PSW
    PUSH ACC

    SETB SCONV  ; sample the analog signal

    ; waiting for the adc to finish sample
    JNB ADC_FLAG, $
    CLR ADC_FLAG


PROGRAM:
    MOV A, ADCDATAL  ; save the low order adc data into the accumulator (we will take only the 4MSBs)
    SWAP A  ; we want the 4MSBs to be in the low order location
    ANL A, #00001111B  ; we dont care about 4 MSB now because they were the 4LSBs before the swap
    MOV R2, A  ; R2 saves the 4lsb in the new 8bit combined register

    MOV A, ADCDATAH  ; we know that in 8 bit mode the 4 high bits of ADCDATAH are zeros anyway
    SWAP A  ; we want the 4LSBs to be in the high order location
    MOV R3, A  ; R3 saves the 4msbs in the new 8bit combined register

    CLR A  ; ensures that accumulator is cleared

    ; combine the results into 8bit register
    MOV A, R2
    ADD A, R3
    MOV R4, A ; combined


    MOV A, R4  ; the accumulator saves the offset divided by 4, from the start of the volts table
    MOV B, #4D  ; multiply it by 4 to get the real offset of the 4 bits string (any volt lvl is in the format: "x.xx", length of 4)
    MUL AB  ; according to table we built, each voltage level its in location of multiplication of 4
    MOV DPTR, #VOLTS  ; dptr point to the start of the table


    ; max offset is 250(for 2.5 volts)*4 = 1000d that can be represented in atleast 10 bits so its devided between two 8 bits register
    ; that can save together offset of length 16 bits

    ; A contains the 8 low bits of the offset - going to DPL
    ADD A, DPL
    MOV DPL, A

    ; B contains the 8 high bits of the offset - going to DPH
    MOV A, B
    ADD A, DPH
    MOV DPH, A

    ;MOV R3, A ; the string address
    ;MOV DPTR, A


    MOV R5, #4D ; repeat 4 times - length of output
    CLR REN  ; block received signals while transmiting string
TRAN_STRING:
    CLR A
    MOVC A, @A+DPTR  ; get character
    MOV SBUF, A  ; transmit to the uart
    JNB TI_FLAG, $  ; wait for transmitting over
    CLR TI_FLAG  ; allow transmitting other characters
    INC DPTR  ; move on to the next character
    DJNZ R5, TRAN_STRING  ; repeat r5 times

    MOV SBUF, #13D  ; transmit carriage return
    JNB TI_FLAG, $
    CLR TI_FLAG
    MOV SBUF, #10D  ; transmit line feed
    JNB TI_FLAG, $
    CLR TI_FLAG

    SETB REN  ; allow signals again
    POP ACC
    POP PSW

    JMP POLLING


    INVALID_INPUT:  CLR REN
                PUSH PSW
                PUSH ACC
                CLR A
                MOV DPTR, #ERR
                MOV R5, #16D
     PRINTING:
                MOVC A, @A+DPTR
                MOV SBUF, A
                JNB TI_FLAG, $  ; wait for transmitting over
                CLR TI_FLAG
                INC DPTR  ; move on to the next character
                DJNZ R5, PRINTING
                SETB REN  ; allow signals again
                POP ACC
                POP PSW
                SETB REN

                RETI
;____________________________________________________________________
                                                        ; VOLTS TABLE

CSEG AT 150H
ERR:
    DB 'INVALID ERROR'
    DB 13
    DB 10
    DB 0

CSEG AT 0200H

VOLTS:

    ; theoretically the voltage that can be represented in 8 bit register can arrive to 2.55[v] but
    ; practically the Vref is just 2.5[v] so its never can reach this value
    DB '0.00'
    DB '0.01'
    DB '0.02'
    DB '0.03'
    DB '0.04'
    DB '0.05'
    DB '0.06'
    DB '0.07'
    DB '0.08'
    DB '0.09'
    DB '0.10'
    DB '0.11'
    DB '0.12'
    DB '0.13'
    DB '0.14'
    DB '0.14'
    DB '0.15'
    DB '0.16'
    DB '0.17'
    DB '0.18'
    DB '0.19'
    DB '0.20'
    DB '0.21'
    DB '0.22'
    DB '0.23'
    DB '0.24'
    DB '0.25'
    DB '0.26'
    DB '0.27'
    DB '0.28'
    DB '0.29'
    DB '0.30'
    DB '0.31'
    DB '0.32'
    DB '0.33'
    DB '0.34'
    DB '0.35'
    DB '0.36'
    DB '0.37'
    DB '0.38'
    DB '0.39'
    DB '0.40'
    DB '0.41'
    DB '0.42'
    DB '0.43'
    DB '0.44'
    DB '0.45'
    DB '0.46'
    DB '0.47'
    DB '0.48'
    DB '0.49'
    DB '0.50'
    DB '0.51'
    DB '0.52'
    DB '0.53'
    DB '0.54'
    DB '0.55'
    DB '0.56'
    DB '0.57'
    DB '0.58'
    DB '0.59'
    DB '0.60'
    DB '0.61'
    DB '0.62'
    DB '0.63'
    DB '0.64'
    DB '0.65'
    DB '0.66'
    DB '0.67'
    DB '0.68'
    DB '0.69'
    DB '0.70'
    DB '0.71'
    DB '0.72'
    DB '0.73'
    DB '0.74'
    DB '0.75'
    DB '0.76'
    DB '0.77'
    DB '0.78'
    DB '0.79'
    DB '0.80'
    DB '0.81'
    DB '0.82'
    DB '0.83'
    DB '0.84'
    DB '0.85'
    DB '0.86'
    DB '0.87'
    DB '0.88'
    DB '0.89'
    DB '0.90'
    DB '0.91'
    DB '0.92'
    DB '0.93'
    DB '0.94'
    DB '0.95'
    DB '0.96'
    DB '0.97'
    DB '0.98'
    DB '0.99'
    DB '1.00'
    DB '1.01'
    DB '1.02'
    DB '1.03'
    DB '1.04'
    DB '1.05'
    DB '1.06'
    DB '1.07'
    DB '1.08'
    DB '1.09'
    DB '1.10'
    DB '1.11'
    DB '1.12'
    DB '1.13'
    DB '1.14'
    DB '1.15'
    DB '1.16'
    DB '1.17'
    DB '1.18'
    DB '1.19'
    DB '1.20'
    DB '1.21'
    DB '1.22'
    DB '1.23'
    DB '1.24'
    DB '1.25'
    DB '1.26'
    DB '1.27'
    DB '1.28'
    DB '1.29'
    DB '1.30'
    DB '1.31'
    DB '1.32'
    DB '1.33'
    DB '1.34'
    DB '1.35'
    DB '1.36'
    DB '1.37'
    DB '1.38'
    DB '1.39'
    DB '1.40'
    DB '1.41'
    DB '1.42'
    DB '1.43'
    DB '1.44'
    DB '1.45'
    DB '1.46'
    DB '1.47'
    DB '1.48'
    DB '1.49'
    DB '1.50'
    DB '1.51'
    DB '1.52'
    DB '1.53'
    DB '1.54'
    DB '1.55'
    DB '1.56'
    DB '1.57'
    DB '1.58'
    DB '1.59'
    DB '1.60'
    DB '1.61'
    DB '1.62'
    DB '1.63'
    DB '1.64'
    DB '1.65'
    DB '1.66'
    DB '1.67'
    DB '1.68'
    DB '1.69'
    DB '1.70'
    DB '1.71'
    DB '1.72'
    DB '1.73'
    DB '1.74'
    DB '1.75'
    DB '1.76'
    DB '1.77'
    DB '1.78'
    DB '1.79'
    DB '1.80'
    DB '1.81'
    DB '1.82'
    DB '1.83'
    DB '1.84'
    DB '1.85'
    DB '1.86'
    DB '1.87'
    DB '1.88'
    DB '1.89'
    DB '1.90'
    DB '1.91'
    DB '1.92'
    DB '1.93'
    DB '1.94'
    DB '1.95'
    DB '1.96'
    DB '1.97'
    DB '1.98'
    DB '1.99'
    DB '2.00'
    DB '2.01'
    DB '2.02'
    DB '2.03'
    DB '2.04'
    DB '2.05'
    DB '2.06'
    DB '2.07'
    DB '2.08'
    DB '2.09'
    DB '2.10'
    DB '2.11'
    DB '2.12'
    DB '2.13'
    DB '2.14'
    DB '2.15'
    DB '2.16'
    DB '2.17'
    DB '2.18'
    DB '2.19'
    DB '2.20'
    DB '2.21'
    DB '2.22'
    DB '2.23'
    DB '2.24'
    DB '2.25'
    DB '2.26'
    DB '2.27'
    DB '2.28'
    DB '2.29'
    DB '2.30'
    DB '2.31'
    DB '2.32'
    DB '2.33'
    DB '2.34'
    DB '2.35'
    DB '2.36'
    DB '2.37'
    DB '2.38'
    DB '2.39'
    DB '2.40'
    DB '2.41'
    DB '2.42'
    DB '2.43'
    DB '2.44'
    DB '2.45'
    DB '2.46'
    DB '2.47'
    DB '2.48'
    DB '2.49'
    DB '2.50'
END START