TRIS setting for the DS1302
Hi all
I wonder if someone could please tell me what the TRIS settings should be to work with the DS1302.
I have been checking out code examples through the forums and have even tried a few. I am still not sure of what the TRIS settings should be for my PIC to interact with the DS1302.
So given the following for example :
Kind regardsCode:RST var PORTA.2 IO var PORTC.1 SCLK var PORTC.3
Dennis
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I2CREAD/WRITE takes care of that for you.
Dave
Always wear safety glasses while programming.
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Oh....
@Dave thanks a million for that reply, it has sent me hurtling off to understand I2Cread and I2Cwrite.
Can anyone confirm the use of a DS1302 with I2Cread/WRITE or should I rather be using the SHIFTIN/OUT displayed in most of the forum threads regarding the DS1302.
I really would appreciate some help regarding the DS1302 and a kickstart of sorts.
Kind regards
Dennis
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I suspect you use serial (SHIFTOUT) with the 1302.
I know you use I2C with the 1307.
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From CocaColaKid:
I have used an assembler routine with the 1302 (in a basic program) and it works:Code:'-------------------------- 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
Cheers, Art.Code:#define SPI_CLK PORTA,1 ; spi bus clock line #define SPI_MOSI PORTA,2 ; spi master out data #define SPI_MISO PORTA,3 ; spi slave input data #define SPI_CE PORTA,4 ; chip enable for SPI device SCRATCH equ 0x40 ; 1 by general purpose scratchpad TMP equ 0x41 ; temp register TMP2 equ 0x42 ; temp register COUNT equ 0x43 ;YRS equ 0x44 ;MON equ 0x45 ;DOW equ 0x46 ;DAYS equ 0x47 ;HRS equ 0x48 ;MINS equ 0x49 ;SECS equ 0x4a ;user_bits equ 0x2C ; ;save_w equ 0x38 ;save_status equ 0x39 ;---- Read RTC into W (assume address already sent) ---- ;---- assumes CE is asserted ---- read_RTC: movlw 08h ;Send 8 bits movwf COUNT SPI_read_loop: rlf TMP, 1 bcf SPI_CLK ; clock data out bcf TMP, 0 ; assume data out is low btfsc SPI_MISO bsf TMP, 0 ; if data out=1, set bit bsf SPI_CLK decfsz COUNT, 1 goto SPI_read_loop movf TMP, W return ;--- Write the byte in W to RTC --- ;---- assumes CE is asserted ---- write_RTC: movwf TMP ;Save the data ; ;--- Do a SPI bus write of byte in 'TMP' --- ; SPI_write: movlw 08h ;Send 8 bits movwf COUNT SPI_w_loop: bcf SPI_CLK bcf SPI_MOSI ; assume data out is low btfsc TMP, 7 bsf SPI_MOSI ; if data out=1, set bit SPI_w_cont: rlf TMP, 1 bsf SPI_CLK ; clock it in decfsz COUNT, 1 goto SPI_w_loop return
Last edited by Art; - 21st February 2010 at 21:06.
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starting to make more sense (I think !)
@ Art
Thanks a million for the reply.
I had already checked out code by Cocacolakid as well as Sayzer and quite a few others, as well as Melanie's example MN1307.txt, with little or no success.
The code from Cocacolakid uses the shiftin/out method not so ?
This is the reason why I asked about the TRIS statement.
Check the first few lines of Cocolakid's code:
What should the TRIS statement be ? Or is this handled by the SHIFTIN/OUT statement ?Code:'-------------------------- Clock Variables --------------------------------- rst var portb.2 ' DS1302 Reset Pin clk var portb.1 ' DS1302 Clock Pin dq var portb.0 ' DS1302 Data Pin
Later on in his code there is :
The forum is scattered with many examples for DS1302 and DS1307 and various timers, clocks elapsed timers, olympic clocks and there are even examples for the various LABX boards,even some methods to use a PIC as a timer with accuracy much like that of a DS1302/7 depending on the crystal you choose.Code:'------------------------ Initial Settings For Ports ------------------------ low rst ' Set reset pin low low clk ' Set clock pin low trisb = 0 trisa = 0
With the wealth of information here it starts becoming rather difficult to figure out which clock chip is a good selection and why.
From what I can see (and I may well be wrong),
if you're using the DS1302 then you should use a shiftin/out method and
if you're using a DS1307 you should use the I2C method.
I am trying to build a very simple alarm clock which triggers on a matching date and time. It will also be used as a datalogger for logging the time and duration of power failures for my generator since we have many power failures in our area at some really odd times.
Your info has been most useful in starting to figure out some parts of this puzzle.
Any more info you or anyone else would also be most welcome.
Kind regards
Dennis
Last edited by Dennis; - 21st February 2010 at 22:06.
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