ds1307

[mel4853]

I'm trying to read a ds1307 using code that Bruce wrote but it will only show 00:00:00 for time & date. I'm using real pic simulator. Do I blame it on simulator & go on?



DEFINE OSC 4

' Note: use 10K pull-up resistors on both SDA and SCL lines.
' DS1307 control pins
SDA Var PORTB.0 ' DS1307 SDA pin #5
SCL Var PORTB.1 ' DS1307 SCL pin #6

' Variables
DB Var BYTE[8] ' Data byte array
RTCSec Var DB[0] ' alias individual bytes in array
RTCMin Var DB[1]
RTCHour Var DB[2]
RTCDay Var DB[3]
RTCDate Var DB[4]
RTCMonth Var DB[5]
RTCYear Var DB[6]
RTCCtrl Var DB[7]
AMPM Var BIT
AM Con 0
PM Con 1

' Port configuration
TRISB = 0
TRISA = 0
CMCON = %00000111 ' Comparators = off

' 12-hour mode clock routine for the DS1307 RTC
GOSUB Write_1307 ' Write time & date on power-up

Main:
GOSUB Read_1307 ' Read the time & date

' Now display it
HSEROUT ["Time: "]
HSEROUT [DEC((RTCHour>>4)& $01), DEC(RTCHour & $0f),":"]
HSEROUT [DEC((RTCMin>>4)& $0f), DEC(RTCMin & $0f),":"]
HSEROUT [DEC((RTCSec>>4)& $0f), DEC(RTCSec & $0f)]

AMPM = RTCHour.0[5] ' Bit 5 of RCTHour indicates AM or PM

IF AMPM = AM THEN ' If RTCHour.bit5 = 0 it's AM
HSEROUT [" AM",13,10] ' Print AM
ELSE ' Else it's PM
HSEROUT [" PM",13,10] ' Print PM
ENDIF

HSEROUT ["Day: ", DEC(RTCDay & $07),13,10]
HSEROUT ["Date: ", DEC((RTCMonth>>4)& $01), DEC(RTCMonth & $0f),":"]
HSEROUT [DEC((RTCDate>>4)& $03), DEC(RTCDate & $0f),":"]
HSEROUT [DEC(((RTCYear>>4)& $0f)*100),DEC(RTCYear & $0f),13,13,10]
PAUSE 1000
GOTO Main

Read_1307:
' Read order is in Secs,Mins,Hours,Day,Date,Month,Year,Control
I2CRead SDA,SCL,$D0,$00,[STR DB\8] ' Read string of 8 bytes from DS1307
RETURN

Write_1307:
' $71 in the Hours register would make it 11 PM
' $51 in the Hours register would make it 11 AM
'
' Example:
' $51 = %0101 0001 <-- 1's position of hour
' ||||_________ 10's position of hour. 10+1 = 11 O-clock
' |||__________ 1 = PM, 0 = AM (in 12-hour mode)
' ||___________ 1 = 12-hour mode, 0 = 24-hour mode
' |____________ ignore this bit
'
' Set time & date to 11:59:00, Day 2, Date:Month:Year 30:08:2007
I2CWRITE SDA,SCL,$D0,$00,[$00,$59,$51,$02,$30,$08,$27,$90] ' Write to DS1307
RETURN ' Sec Min Hr Day D M Y Control

End

[Darrel Taylor]

I don't know anything about that simulator, but that code seems to work fine in the Proteus Simulator with a 16F88.
What chip are you using?

http://support.melabs.com/DT/DS1307_Bruce.jpg

[mel4853]

I'm using a 16F690. I have never used any rtc's at all so don't know if my simulator will do this. It does have a rtc ds1307 in it though. My simulator is keeping time off the computers time.This is my chip set up:


TRISC = %00000000
TRISB = %00000000
TRISA = %000000
CM1CON0.7 = 0 ' Comparators = off
CM2CON0.7 = 0 ' Comparators = off
ANSEL = %00000000
ANSELH = %00000000

[Darrel Taylor]

The code specifies PORTB.0 and PORTB.1 as SDA and SCL.
But the 16F690 doesn't have either RB0 or RB1, it only has RB4-RB7.

What pins are the DS1307 connected to in your simulation?

[mel4853]

SDA to PORTA.0 & SCL to PORTA.1 sorry forgot to post that also.

[Darrel Taylor]

Using a 16F690 with the changes you posted ... It still works.

I can't comment on the simulator you are using.
But I think you can assume the problem is not in Bruce's code.

http://support.melabs.com/DT/DS1307_16F690.jpg

[mel4853]

Thanks Darrel really thought it was my simulator, now I know that. Thanks again, will look more into how this works with my simulator or if I'm just SOL.

[Chirpy]

Some simulators wont set the time automatically to system time, Ive run into this in the past, but just have your PIC chip check the time on startup and if it's all 0s, have it set the time through the code to a certain time or date. They do that for more realistic hardware, just like as if you were to hook up a blank ds1307 chip up and just started using it.