Real Time Clock with PIC

[VRL_15]

I want to implement RTC without using any timer in PIC 16F887.

I just want to read the time from RTC and display it on LCD in Hours: MIn: Sec format.

I tried the following code bt it did not work. Please help me out.

RTC_rd:
call I2C_STRT
movlw 0XD0 ; slave address + write
movwf I2C_Value
call I2C_SEND
movlw 0X00 ; set word address to seconds register
movwf I2C_Value
call I2C_SEND
call I2C_STRT
movlw 0XD1 ; slave address + read
movwf I2C_Value
call I2C_SEND
call read_RTC ; read the seconds data
movwf SECS ; save it
call ack

movlw 0X01 ; set word address to seconds register
movwf I2C_Value
call I2C_SEND
call I2C_STRT
movlw 0XD1 ; slave address + read
movwf I2C_Value
call I2C_SEND
call read_RTC ; read the seconds data
movwf MINS
call ack

movlw 0X02 ; set word address to seconds register
movwf I2C_Value
call I2C_SEND
call I2C_STRT
movlw 0XD1 ; slave address + read
movwf I2C_Value
call I2C_SEND
call read_RTC ; read the seconds data
movwf SECS
call nack
call I2C_STP
return

read_RTC:

bsf I2C_DTA ; set SDA for input
movlw 0x08 ; send 8 bits
movwf COUNTER5

bcf I2C_CLOCK ; SCL low (output)
clrf I2C_Value ; clear var
;rlf I2C_Value, 1 ; rotate carry in
;clrf I2C_Value ; clear var again

I2C_read_loop:
rlf I2C_Value, 1

bsf I2C_CLOCK ; SCL high (input)
btfsc PORTC,4
bsf I2C_Value, 0 ; if data out = 1, set bit

;bcf I2C_CLOCK

bcf I2C_CLOCK ; SCL low (output)

decfsz COUNTER5, 1
goto I2C_read_loop

movf I2C_Value, 0

return

ack:
bcf I2C_DTA ; set SDA for output
bsf I2C_CLOCK ; SCL high (input)

;nop
bcf I2C_CLOCK

;bcf I2C_CLOCK ; SCL low (output)
return



nack:
bsf I2C_DTA
bcf I2C_DTA ; set SDA for output
bsf I2C_CLOCK ; SCL high (input)
bcf I2C_CLOCK ; SCL low (output)

return

 

[VRL_15]

**broken link removed**

I tried the above link but it did not solve the problem.

I just want to read the data from DS1307(RTC) and not write anything to the RTC.

If anyone has an idea, please let me know.

Thank you.

 

[VRL_15]

anyone an idea please?

 

[VRL_15]

I am still finding it really difficult to just read the hours, minutes and seconds from DS1307 and display it on LCD.

If anyone has an idea please help me out.

I have tried another code but didn't work

RTC:
call read_RTC
read_regs:
movf SECS,0
call writebcd
;movwf temp15
;movlw 0xCB
;movwf PORTD
;call SND_CMD
;movf temp15,0
;movwf PORTD
;call SND_DTA
return
read_RTC:
call I2C_STRT
movlw 0xD0
movwf I2C_Value
call I2C_SEND
movlw 0x00
movwf I2C_Value
call I2C_SEND
call I2C_STRT
movlw 0xD1
movwf I2C_Value
call I2C_SEND
movlw 0x00
movwf I2C_Value
call I2C_SEND
call I2C_RD
movwf SECS
call I2C_STP
return
writebcd:
movwf temp16
swapf temp16,0
andlw 0x0F
addlw 0x06
btfss STATUS,DC
call lessnine
addlw 0x31
goto digit1

lessnine:
addlw 0x2A
return
digit1:
movlw 0xCB
movwf PORTD
call SND_CMD
movf temp16,0
movwf PORTD
call SND_DTA
return
I2C_RD:
bcf STATUS,RP1
bsf STATUS,RP0
clrf TRISC
bsf TRISC,4
bcf STATUS,RP1
bsf STATUS,RP0
clrf I2C_Value

movlw 0x08
movwf COUNTER5
goto I2C_read_loop
;rlf I2C_Value,1
;clrf I2C_Value
I2C_read_loop:
rlf I2C_Value,1
bsf I2C_CLOCK
btfsc PORTC,4
bsf I2C_Value,0
bcf I2C_CLOCK
decfsz COUNTER5,1
goto I2C_read_loop

movf I2C_Value,0
return

 

[VRL_15]

I am sure someone must have done this before.

Just reading the time from DS1307 and display it on LCD

Guys, please help me out

Thank you

 

[VRL_15]

there have been 87 views and no reply

has anyone never displayed the time on LCD by only reading it from DS1307???

 

[blueroomelectronics]

1. Learn to use code-tags;
2. Liberally comment your code
3. A schematic might be helpful, even if it is a simple I2C clock.