eelcor 18 Posted August 25, 2013 Share Posted August 25, 2013 Hi everybody, As a part of my long term project building wireless sensor nodes, I have been looking for a nice RTC chip. First I was drawn to the DS1307, but this part is 5V and only a clock without alarm functions. Googling to the internet I've found the PCF8563. This part is a "drop in" replacement for the DS1307, but offers a lower supply voltage (3.3V) and includes alarm functions. The chips can be sourced quite cheap from the internet and work like a charm with both 6pf and 12pf 32768kHz crystals. A nice tutorial how to connect these things can be found using the following link: http://startingelectronics.com/beginners/start-electronics-now/tut16-arduino-clock/ It is written for the Arduino but can be adapted easily to the launchpad. Just change the LiquidCrystal pins to free pins on the Arduino and voila there you have a nice RTC that can be used for sprinkler projects or other projects. The alarm can be set on different days of the week (not a specific date), but with some program logic a calendared version should be possible. I am thinking of writing a library out of the tutorial. Anyone interested? Kind regards, Eelco Desmond, chibiace, Rickta59 and 1 other 4 Quote Link to post Share on other sites
Desmond 0 Posted August 26, 2013 Share Posted August 26, 2013 Thanks for that tip. Quote Link to post Share on other sites
chibiace 46 Posted August 27, 2013 Share Posted August 27, 2013 cool Quote Link to post Share on other sites
bluehash 1,581 Posted August 27, 2013 Share Posted August 27, 2013 I am thinking of writing a library out of the tutorial. Anyone interested? Kind regards, Eelco Yes, that would be great! If you want some parts sourced, PM me. Quote Link to post Share on other sites
Rei Vilo 695 Posted August 27, 2013 Share Posted August 27, 2013 Another nice option is the NXP PCF2129A. The PCF2129A operates at 3.3V, embeds the quartz crystal and requires no passive components. reaper7 1 Quote Link to post Share on other sites
eelcor 18 Posted August 27, 2013 Author Share Posted August 27, 2013 That sounds like a great option! I cannot determine if it is a DIP package or a SO package. Great to chose between SPI and I2C. Any ideas regarding the command set? Kind regards, Eelco Quote Link to post Share on other sites
eelcor 18 Posted August 27, 2013 Author Share Posted August 27, 2013 One of the advantages of the chip I found is that they can be found on ebay for really low prices. But the built in crystal is very tempting! Quote Link to post Share on other sites
Rei Vilo 695 Posted August 28, 2013 Share Posted August 28, 2013 The PCF2129A is a SOIC20 package. I've soldered it on a DIP14 support and I'm using it in I2C mode. For I2C SCL(1) = I2C clock SDA(4) = I2C data IFS(5) connected to BBS(18) = output voltage to select I2C SDI(2) connected to VSS(8) = ground VDD(20) = +3.3V VBAT(19) = optional battery VSS(8) = ground For I2C, don't forget to use pull-ups resistors for SDA and SCL. For SPI, not tested SCL(1) = SPI clock SDI(2) = SPI MOSI SDO(3) = SPI MISO CE(4) = SPI chip enable, active low IFS(5) connected to VSS(8) = ground to select SPI VDD(20) = +3.3V VBAT(19) = optional battery VSS(8) = ground Quote Link to post Share on other sites
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