PIC16F887 and DS1307

Printable View

- 26th June 2008, 19:53
menta

PIC16F887 and DS1307

I've been reading all posts here regarding the DS1307 RTC, but I really can't get it to work.
I just get the value '0' when trying to read it.
Is soething in my code is wrong ?

Code:

RTCSec var byte ' Seconds RTCMin var byte ' Minutes RTCHour var byte ' Hours RTCWDay var byte ' Weekday RTCDay var byte ' Day RTCMonth var byte ' Months RTCYear var byte ' Year RTCCtrl var byte ' Control SetTime var byte ' 12/24 Hour Clock SetSec var byte ' Seconds SetMin var byte ' Minutes SetHour var byte ' Hours SetDay var byte ' Day SetMonth var byte ' Months SetYear var byte ' Year TimeOut var word ' Variable for SetUp Menu Time-Out RTCSec=1 RTCMin=4 I2CWRITE PORTC.4,PORTC.3,$D0,$00,[RTCSec,RTCMin,RTCHour,RTCWDay,RTCDay,RTCMonth,RTCYear,RTCCtrl] pause 100 main: I2CRead PORTC.4,PORTC.3,$D0,$00,[RTCSec,RTCMin,RTCHour,RTCWDay,RTCDay,RTCMonth,RTCYear,RTCCtrl] SEROUT PORTC.6,6,[254,1] toggle PORTD.7 : pause 1000 SEROUT PORTC.6,6,[254,128,#RTCSec] pause 1000 goto main
- 26th June 2008, 19:59
skimask

Quote:

Originally Posted by menta

I've been reading all posts here regarding the DS1307 RTC, but I really can't get it to work.
I just get the value '0' when trying to read it.
Is soething in my code is wrong ?

A quick search on DS1307 will get you a long way. But since your SEARCH function seems to be broken, I'll show you use mine.
http://rentron.com/PicBasic/SERLED.htm
No, this code isn't 100% perfect for what you need, but I'll bet ANYTHING that you can easily modify for your purposes.

And besides, why are you trying to set the same time that you're trying to read?
If the set time is zero and the read time is zero, then it seems to me that your program, if that is the whole program, is working correctly.

Got any pullups on the I2C lines?
- 26th June 2008, 20:54
menta

Well, i write the time, then I keep reading it, isn't it suppose to be chance every second when I keep reading it ?
pullups, you mean resistors ? I tried, then I only got 16 or 32 instead of 0
- 27th June 2008, 02:56
skimask

Quote:

Originally Posted by menta

Well, i write the time, then I keep reading it, isn't it suppose to be chance every second when I keep reading it ?

I don't know if it's supposed to chance every second, but if the clock is running, it may change every second.

Quote:

pullups, you mean resistors ? I tried, then I only got 16 or 32 instead of 0

Complete this sentence:
The value of my resistors connected to +5v and to the I2C clock and data line is __________."
- 27th June 2008, 10:14
menta

Quote:

Originally Posted by skimask

The value of my resistors connected to +5v and to the I2C clock and data line is ____10k____."

..........
- 27th June 2008, 23:34
amgen

rtc

control register may need to be set

alsoooooo....
the I2c read and write address/control string have to be different, I just used binary 00011110 (just an example) to make sure the read write is correctly coded.

don
- 28th June 2008, 00:34
menta

tried that already. It doesn't help.
What do you mean by "the I2c read and write address/control string have to be different" ?
- 28th June 2008, 01:48
amgen

rtc

RTCADW CON %11010000 'DS1307 RTC ADDRESS SEND...RECEIVE
RTCADR CON %11010001

I2CWRITE SDA,SCL,RTCADW,7 ,%00010011 'TURN ON SQU WAVE OUT 32k HZ

I2CREAD SDA,SCL,RTCADR,0,[RTC[1],RTC[2],RTC[3],RTC[4],RTC[5],RTC[6],RTC[7]]

from my rtc stuff
don
- 28th June 2008, 02:05
menta

Ok, So I tried to use your example.
Still getting '0' when reading. If i use 10K resistors on the SDA and SCL I get '16'

Code:

INCLUDE "modedefs.bas" RTC VAR BYTE[8] ' Data byte array RTCADW CON %11010000 'DS1307 RTC ADDRESS SEND...RECEIVE RTCADR CON %11010001 SDA var PORTC.4 SCL var PORTC.3 pause 1000 I2CWRITE SDA,SCL,RTCADW,7,%00010011 'TURN ON SQU WAVE OUT 32k HZ main: ;I2CREAD PORTC.4,PORTC.3,%11010000,$00,[RTCSec] I2CREAD SDA,SCL,RTCADR,0,[RTC[1],RTC[2],RTC[3],RTC[4],RTC[5],RTC[6],RTC[7]] SEROUT PORTC.6,6,[254,1] toggle PORTD.7 : pause 1000 SEROUT PORTC.6,6,[254,128,#RTC[1]] pause 1000 goto main
- 28th June 2008, 03:02
amgen

well,
data on 1307 is hex so.......

SEROUT2 PORTA.0,6,1,[ "_T" ,HEX RTC[6],"/",HEX2 RTC[5],"/20",_
HEX2 RTC[7]," , ",HEX RTC[3],":",HEX2 RTC[2],":",HEX2 RTC[1]," ",RTC[9],"M _" ]
( use your own port etc.)

the voltage on SCL & SDA (to gnd) has to be +5 at rest, no signal . Thats what the 10k resisters do.

also, you can check square wave out at 1 HZ with led/resister on the output pin of 1307 as visual check of rtc.
I2CWRITE SDA,SCL,RTCADW,7,%00010000 'TURN ON SQU WAVE OUT to...1... HZ
- 28th June 2008, 06:53
skimask

PBP handles the R/W bit for you just like it says in the manual...so...

Code:

INCLUDE "modedefs.bas" RTC VAR BYTE[8] ' Data byte array RTC CON %11010000 'DS1307 RTC ADDRESS SEND...RECEIVE SDA var PORTC.4 SCL var PORTC.3 pause 1000 I2CWRITE SDA,SCL,RTC,7,%00010011 'TURN ON SQU WAVE OUT 32k HZ main: I2CREAD SDA,SCL,RTC,0,[RTC[1],RTC[2],RTC[3],RTC[4],RTC[5],RTC[6],RTC[7]] SEROUT PORTC.6,6,[254,1] toggle PORTD.7 : pause 1000 SEROUT PORTC.6,6,[254,128,#RTC[1]] pause 1000 goto main
- 28th June 2008, 10:58
menta

well,
I can't get any signal on the SWQE output, not by LED or by the logic analyzer of the PICkit2. So I might guess the 1307 is malfunctioning.
This is what I get when analyzing the SCL vs SDA
http://dj-gil.com/PIC/posts/SCL-SDA.JPG
This is what I get when analyzing the SCL vs SWQ
http://dj-gil.com/PIC/posts/SCL-SQW.JPG
This is what I get when analyzing the SCl vs SDA
- 28th June 2008, 15:08
Bruce

Here are a few things that 'may' help;

1. If you're using an oscillator >8MHz, then you'll want to include DEFINE I2C_SLOW 1
since the 1307 max clock speed is 100kHz.

2. The SQW output is an open-drain type. I.E. it cannot output a logic 1. Use a 10K
pull-up on the SQW output. Then you should see a square wave output on your scope.

3. Use the external pull-ups on SDA and SCL.

4. Connect a 3V battery to the 1307 Vbat input.
- 29th June 2008, 20:47
menta

non of the above really helps.
Probably the 1307 is dead.
- 4th July 2008, 21:28
menta

I replaced the DS1307 with VS1307 which seems to work.
Is there any other way to convert the data to dec other than:

I2CRead SDA, SCL, $D0, $00, [A]
Sec1=(A.0*1)+(A.1*2)+(A.2*4)+(A.3*8)
Sec10=(A.4*1)+(A.5*2)+(A.6*4)
- 5th July 2008, 21:57
menta

Now I need to understand how to convert from decimal (which comes from the user setup) to write to the RTC chip.
- 5th July 2008, 22:27
menta

Found it
ConvertBCD:
CounterB=CounterA DIG 1
CounterB=CounterB<<4
CounterB=CounterB+CounterA DIG 0
Return
- 7th July 2008, 05:25
skimask

Quote:

Originally Posted by menta

Found it

What happens if CounterA = $EC?
- 7th July 2008, 08:32
Melanie

We're talking about a DS1307 RTC here (and ignoring the MSB of certain Registers) where the only valid individual digits are in the range 0-9. The subroutine converts two digit DECIMAL in the range 0-99 to a single BCD Byte. $EC is not a valid conversion requirement for this application.
- 7th July 2008, 20:39
skimask

Quote:

Originally Posted by Melanie

$EC is not a valid conversion requirement for this application.

My point was that there isn't any sort of error checking, flipped bits, logic errors, and so on...
- 29th September 2008, 15:54
crisxstyle

Hi!!!
I just wan't to know if its possible how i can set manualy the initial time of the clock using a bic basic code!i tried to do it but i found some problems due to bcd and hex code!
so there someone that do it?!?!

thank you so much

bye bye Cris
- 29th September 2008, 17:05
skimask

Quote:

Originally Posted by crisxstyle

Hi!!!
I just wan't to know if its possible how i can set manualy the initial time of the clock using a bic basic code!i tried to do it but i found some problems due to bcd and hex code!
so there someone that do it?!?!

96 hits on these forums alone for ds1307...
Surely there's something in one of those threads to help you out...