real time clock

[maria]

Hi there,

I'm using PIC BASIC with a PIC16F877. I'm wondering if there's anyone out there who could tell me how to connect a real time clock IC (the Dallas DS1302 is the one I have) to the PIC and get the PIC to display the time on an LCD? I have my LCD up and running so I wouldnt need too much detail on the LCD bit.

Thanks!

Best Wishes,
Maria.

[Melanie]

Have a look at the RTC thread in ths section (set your display to show posts from the last 30 days or more).

PS. Posts do get read by folks regardless what section you post them in... posting in multiple sections is unnescessary.

[longpole001]

I know this is old thread but have a need fro RTC and its using the ds1302

i did have a quick question in relation to how the I/O port is set on the PIC for I/O the interface to the DS1302 , in that the sample code does not change TRIS bits on the PIC from an output to an input for when it doing a read ( shiftin command ) of the DS1302 -

does issuing the shiftin command automatically change the tris bits for that port to allow input ???
cheers

Sheldon

[xapmanis]

Hello longpole, i've been reading the thread today and some others about 1302 and i think shiftin and shiftout does all the work with tris and with clk. Just send the right registers for reading/writing and u should be fine.

[CocaColaKid]

Maria,

You might want to try this code. This is how I control this chip. If you need help with it just ask and I'll see if I can provide you some assistance.

'-------------------------- Clock Variables ---------------------------------

rst var portb.2 ' DS1302 Reset Pin
clk var portb.1 ' DS1302 Clock Pin
dq var portb.0 ' DS1302 Data Pin

'----------------------- Write Commands For DS1302 --------------------------

writectrl con $8E ' Control byte
writeram con $80 ' Write to RAM
writeprotect con $00 ' Write-protect DS1302
writesec con $80 ' Write seconds
writemin con $82 ' Write minutes
writehour con $84 ' Write hour
writedate con $86 ' Write date
writemonth con $88 ' Write month
writeyear con $8C ' Write year

'------------------------- Read Commands For DS1302 -------------------------

readsec con $81 ' Read seconds from DS1302
readmin con $83 ' Read minutes from DS1302
readhour con $85 ' Read hours from DS1302
readdate con $87 ' Read date from DS1302
readyear con $8D ' Read year from DS1302
readmonth con $89 ' Read month from DS1302

'------------------------------ Time Variables ------------------------------

mem var byte ' Temporary data holder
outbyte var byte ' Second byte to ds1302
reg_adr var byte ' First byte to DS1302
date var byte ' Date variable
ss var byte ' Seconds variable
mm var byte ' Minutes varibale
hh var byte ' Hours variable
mo var byte ' Month variable
yr var byte ' Year variable

'------------------------ Initial Settings For Ports ------------------------

low rst ' Set reset pin low
low clk ' Set clock pin low

trisb = 0
trisa = 0

'----------------------- Set Initial Time Variables -------------------------

if portb.4 = 1 then START ' Set inital clock start up if jumper is present
reg_adr = writectrl ' Set to control byte
outbyte = writeprotect ' Set turn off protection
gosub w_out ' Send both bytes
reg_adr = writesec ' Set to write seconds register
outbyte = $00 ' Set to write 00 to seconds register
gosub w_out
reg_adr = writemin
outbyte = $30
gosub w_out
reg_adr = writehour
outbyte = $00
gosub w_out
reg_adr = writedate
outbyte = $01
gosub w_out
reg_adr = writemonth
outbyte = $01
gosub w_out
reg_adr = writeyear
outbyte = $00
gosub w_out
reg_adr = writectrl
outbyte = writeprotect
gosub w_out

start:
reg_adr = readsec ' Read seconds
gosub w_in
ss = mem
reg_adr = readmin ' Read minutes
gosub w_in
mm = mem
reg_adr = readhour ' Read Hours
gosub w_in
hh = mem
reg_adr = readyear ' Read Year
gosub w_in
yr = mem
reg_adr = readdate ' Read Date
gosub w_in
date = mem
reg_adr = readmonth ' Read Month
gosub w_in
mo = mem
lcdout $fe,1,"TIME:",HEX2 hh,":",HEX2 mm,":",HEX2 ss
pause 500
goto start

'----------------------- Time Commands Subroutines --------------------------

w_in:
mem = reg_adr ' Set mem variable to reg_adr contents
high rst ' Activate the DS1302
shiftout dq,clk,0, [mem] ' Send control byte
shiftin dq,clk,1, [mem] ' Retrieve data in from the DS1302
low rst ' Deactivate DS1302
return

w_out:
mem = reg_adr ' Set mem variable to reg_adr contents
high rst ' Activate the DS1302
shiftout dq,clk,0, [mem] ' Send control byte
mem = outbyte ' Set mem variable to outbyte contents
shiftout dq,clk,0, [mem] ' Send data stored in mem variable to DS1302
low rst ' Deactivate DS1302
return

[NL2TTL]

when i use this code, with a serout commando the compiler give a error on the code HEX2.

And when i leave the HEX2 in the serout and replace them bij # the counting gives problems what does the hex2 does, and how can i display the time and date on a console pc with the serout command?

[NavMicroSystems]

RTFM

There is no HEX modifier with SEROUT, use SEROUT2 instead.

see PBP Manual Section 5.73 & 5.74

[NL2TTL]

already fix the problem use the and and shift >>4 function

[Art]

Hey CocaColaKid, thanx for the code it worked, however, I suggest an improvement as stated in the DS1302 datasheet U R supposed to read
the seconds again at the end in case the second ticks over from 59 to
00 while you were reading the mins, hrs, etc. this could result in erroneous
Real Time reading.

Suggest modification here:
ss var byte 'seconds
ss2 var byte 'seconds comparison byte

start:
reg_adr = readsec ' Read seconds
gosub w_in
ss = mem
reg_adr = readmin ' Read minutes
gosub w_in
mm = mem
reg_adr = readhour ' Read Hours
gosub w_in
hh = mem
reg_adr = readyear ' Read Year
gosub w_in
yr = mem
reg_adr = readdate ' Read Date
gosub w_in
date = mem
reg_adr = readmonth ' Read Month
gosub w_in
mo = mem
reg_adr = readsec ' Read seconds
gosub w_in
ss2 = mem
IF ss <> ss2 THEN start 'COMPARE FIRST AND SECOND READINGS AND TRASH IF DIFFERENT.
lcdout $fe,1,"TIME:",HEX2 hh,":",HEX2 mm,":",HEX2 ss
pause 500
goto start

Cheers, Art.

[longpole001]

yes it does change the input /output of the tris control , how ever it not documented in any of the manuals or online help files that i have found to date

[bahattinkor]

dear friends,

I have a problem with the DS1302, PIC16f877 and PIC Proton+ combination. I designed a basic circuit in PROTEUS, and put your code in it. I worked fine. There was no problem. but when I made that circuit real, I met with problems. When I powered the PIC I can not see the time runing. The only thing that I see is " 00:00:80" and it always stays same. I used portd.0,d1 and d2 in the connection of PIc and DS1302. I used 32.768khz crystal. And there is no any mistake in connections. How can I fix this problem ?
And one more small question. How can I reset LCD ? in PicBasic PRo I used to written "Flags=0". In Proton+ what should I write instead of this ?

[mister_e]

For info on Proton... www.picbasic.org/forum

I doubt PROTON have this option or it's hidden somewhere in the Help file, or somewhere on the forum.

BUT try

Print $fe,$28 
Print $fe,$0c 
Print $fe,1

This should work

[bot402]

You should know better than that Steve. The PROTON does everything the PBP does, and a whole lot more!

To reset the LCD, simply use: -

Dim BPF as Byte SYSTEM ' Bring the system variable into BASIC

Clear BPF ' Force a reset on the LCD the next time it's used

However, this is the wrong forum for the PROTON compiler. As long as your not using a pirated version of the compiler, you are welcome to use the dedicated PROTON forum

[BobK]

Hello bahattinkor,

I had the same problem for 2 days using a DS1337. It displayed the default time and if I programmed a new starting time that would display but would continue from there. This was on a printed circuit board that was already working but had a little accident with a floating wire that went into the side of the power supply box and blew everything up! After replacing most of the parts the board worked for a few days then quit. I put new chips on the board again but to no gain. I put all of the same parts into a newer board and they worked fine. Went back to the old board and found no connection between one side of the crystal and the DS 1337.

The moral of this story is triple check your connections and use a meter!

BobK

[bahattinkor]

yes, I checked connections. voltages are normal but when I measured the cyrstal of Ds1302 with ossiloscope, I did not see any frequency. The ossilator does not ossilates. then I change DS1302 and 32.768Khz cyrstal with new ones but they are still not working. Can it be related with the Vcc that I used. I use 5V for Vcc for DS1302. Or Should I use any resistor or capacitor plus for the DS1302.

[engrehaf]

hey guys i am a new member here
i want some help in this topic if you can help

HEX2 !! what it is ?
because i use this sample code for 7 segment display, but i cannot deal with these variable like HEX2 hourx, HEX2 minutex and HEX2 seconds ???

and thank you

[mackrackit]

From the manual

BIN, DEC and HEX may also be followed by a number. Normally, these modifiers display exactly as many digits as are necessary, zero blanked (leading zeros are not sent). However, if a number follows the modifier, SEROUT2 will always send that number of digits, adding leading zeros as necessary. It will also trim of any extra high order digits. For example, BIN6 8 would send A001000" and BIN2 8 would send A00".

[cesar35]

hello know the post and very old I'm in need of a little help on this clock project using the DS1302 with alarm it even works more Think it has error, If anyone can help me I thank here all the files + simulation