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PIC 16F88 SPI Interface with DS3234 RTC

 
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ckielstra



Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands

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PostPosted: Sat Feb 18, 2012 7:42 am     Reply with quote
I'm surprised your code works. From the first page of the DS3234 datasheet:
Quote:
4MHz SPI Bus Supports Modes 1 and 3

You have configured mode 0.

Please, next time use the following defines in your code to make it easier to read and minimize configuration errors like this:
Code:
// SPI Mode | MOTOROLA | MICROCHIP | CCS                          | Clock line idle | Data clocked in at
//----------------------------------------------------------------|-----------------|-------------------
//          | CPOL CPHA|  CKP CKE  |                              |                 |
//    0     |  0    0  |   0   1   | SPI_L_TO_H | SPI_XMIT_L_TO_H | low             | low to high edge
//    1     |  0    1  |   0   0   | SPI_L_TO_H                   | low             | high to low edge
//    2     |  1    0  |   1   1   | SPI_H_TO_L                   | high            | high to low edge
//    3     |  1    1  |   1   0   | SPI_H_TO_L | SPI_XMIT_L_TO_H | high            | low to high edge
//
// Example: setup_spi(SPI_MASTER | SPI_MODE_3 | SPI_CLK_DIV_4 );
//
#define SPI_MODE_0  (SPI_L_TO_H | SPI_XMIT_L_TO_H)
#define SPI_MODE_1  (SPI_L_TO_H)
#define SPI_MODE_2  (SPI_H_TO_L)
#define SPI_MODE_3  (SPI_H_TO_L | SPI_XMIT_L_TO_H)
b.dokimakis



Joined: 12 Feb 2012
Posts: 3

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PostPosted: Sun Feb 19, 2012 3:50 am     Reply with quote
There's some usefull info. I've been looking for the meanings of the SPI modes.
Thanks!
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