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Topic: Cosa: An Object-Oriented Platform for Arduino programming (Read 100 times) previous topic - next topic

kowalski

#105
May 28, 2013, 10:46 pm Last Edit: May 29, 2013, 09:06 am by kowalski Reason: 1
Hi pito!

Thanks for all the feedback and sharing such great improvement ideas. I will need to think about how to add another state machine to handle 1/4 cycle mode.

I pushed an update with basically all your suggestions except the time measurement as the interface will need a tweak for that. The Rotary::Dial became a template class to allow user defined counter data types. Now you don't need to modify the source. Just pass "long" as a parameter to the template.
Code: [Select]

 template<typename T>
 class Dial : public Encoder {
 private:
   T m_value;
   T m_min;
   T m_max;
   T m_step;
   ...
   Dial(Board::InterruptPin clk, Board::InterruptPin dt, Mode mode, T initial, T min, T max, T step) :
     Encoder(clk, dt, mode),
     m_value(initial),
     m_min(min),
     m_max(max),
     m_step(step)
   {}
};
...
Rotary::Dial<int> dial(Board::PCI6, Board::PCI7, Rotary::Encoder::FULL_CYCLE, -100, -100, 10, 1);

You asked about the Cosa/Board mapping. For the Mighty I constructed a continues numbering scheme for the Digital and Analog pins (enum's) but this required remapping of the Interrupt pins as these are numbered differently and they map to four interrupt mask registers.

All and all the Mighty seems to be a very good compromise. The Mega goes a bit over the edge if not combined with external SRAM or >2 UARTs required. I need to get my hands on a few Atmega1284P so that the test suites can run of real hardware. Hope to run some further tests of the Rotary Encoder/Dial on ATtiny84/85 soon.

Cheers!

pito

#106
May 29, 2013, 12:42 am Last Edit: May 29, 2013, 01:09 am by pito Reason: 1
Great! Thanks!
The accelerated dial is nice to have when you need to enter/change a frequency for example. So normal movement will increment in "steps" (ie 1Hz), fast kick into the dial can add ie. 20kHz at once, ie. while the angular speed is considered "fast" the freq step doubles each encoder step (or better "encoder cycle").
The 1284p is the DIP model of choice for experimenters, imho. You might consider it ;)

Idea N.6: dialing of a specific digit within a number . Maybe with an another parameter - "digit" ..
When 0 (default) no action, when 1..10 (ie for long) only a particular digit within the number will incr/decr itself. So one may dial his/her phone number easily :)
That might be applicable to strings as well (writing an sms with the dial)..

kowalski


Great! Thanks!
The accelerated dial is nice to have when you need to enter/change a frequency for example. ...
Idea N.6: dialing of a specific digit within a number . ...

You are welcome!

The accelerated dial is such a great idea so I added a first attempt. It is also a template class with value data type and threshold parameter. Please try it out. The documentation is on-line; http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/db/db1/classRotary.html And there is a snippet in the example sketch.

My guess is that your second dial suggestion (N.6) would require a button or two to step between the digits. I think I understand the style of dial/value interaction you are suggesting. The underlaying value would be simplest a vector or even BCD but also pure binary. I need to think a bit about the position stepping function needed.

I also added graphical versions of the state machines so that they are a bit easier to understand. http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d6/d6e/classRotary_1_1Encoder.html#a5a3983d7031d6c1c84b2c782d41be52b

and http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d6/d6e/classRotary_1_1Encoder.html#abccbcaf327c6ea20a58ca185f81cb32e


Graphviz and dot are such excellent tools for this. The graphs are defined in the source code.

Cheers!

kowalski

#108
Jun 11, 2013, 12:28 pm Last Edit: Jun 23, 2013, 11:42 pm by kowalski Reason: 1
An update on the latest improvements and development of Cosa. The latest focus has been on LCD Displays. In Cosa simple mono-chrome displays are IOStream::Device's which allows printout directly to screen. They also implement handling of a number of special character (when possible):

1. Carriage-return/line-feed (\n)
2. Form feed (\f) => clear display and goto home position (0,0)
3. Back-space (\b) => one step back on current line (if possible)
4. Alert/Bell (\a) => toggle text mode (inverted/normal)
5. Horizontal tab (\t) => set cursor at next tab position

The drivers support basic scrolling of text. Scrolling is implemented without extra SRAM/copy of the screen. Hardware assisted scrolling, changing display memory registers, is used when possible (e.g. ST7565). In other cases simple wrap-around is used. Carriage-return/line-feed will clear the new line.

The following mono-chrome LCD devices are currently supported; ST7565 64x128, PCD8544 48x84, and HD44780 (aka 1602/2004) 16x2/20x4 character LCD. Pixel based LCD device drivers do not support the Canvas drawing operations directly. Instead there is an Offscreen canvas that can be used. This design allows SRAM to be used more efficiently.  





Above are the Cosa classes that support the IOStream::Device interface and can be used with IOStream and replace each other. The ST7735, 262K Color Single-Chip TFT device driver supports the Cosa Canvas interface and all drawing operations with IOStream::Device as Textbox element(s) on screen.

Please find the LCD device driver documentation on-line:

1. HD44780 http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/dd/dd2/classHD44780.html#pub-methods
2. PCD8544 http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/da/d71/classPCD8544.html#pub-methods
3. ST7565 http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d7/d72/classST7565.html#pub-methods
4. ST7735 http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/dc/d6e/classST7735.html#pub-methods

Last, the Cosa LCD drivers work on Arduino Mega, Mighty, Uno, Nano, Mini, etc, all the way down to ATtinyX4/X5. Below is an ATtiny85 running an example sketch with PCD8544 LCD and RF433/Virtual Wire Interface (VWI) receiver. The sketch receives humidity and temperature (DHT11) readings from the ATtiny in the background and displays the reading together with sequence number, message drop statistics, battery voltage and run-time. Note the diode to lower the Lithium 3.7V for the LCD (;-) https://github.com/mikaelpatel/Cosa/blob/master/examples/Tiny/CosaTinyReceiver/CosaTinyReceiver.ino





There is a simple "hello world" sketch that can be used to get some statistics on the foot print of the LCD drivers. https://github.com/mikaelpatel/Cosa/blob/master/examples/LCD/CosaLCDsize/CosaLCDsize.ino
Below is the sketch size in bytes for Arduino Mega/Standard/Tiny builds for the mono-chrome LCD drivers.

1. HD44780: 3312/3088/2868 bytes
2. PCD8544: 4482/4260/3916 bytes
3. ST7565: 5008/4802/4460 bytes

Please note that Cosa does not currently support Arduino Due, Leonardo and other ATmega32u4 based boards.

Cheers!

pito

#109
Jun 11, 2013, 02:47 pm Last Edit: Jun 11, 2013, 03:26 pm by pito Reason: 1
Quote
The accelerated dial is such a great idea so I added a first attempt. It is also a template class with value data type and threshold parameter. Please try it out.

I've tried. It works, but I would suggest another scenario.
The selection of normal and speedy step based on the threshold does not create the effect, just switches the step increment to another constant value.

The idea I have described above is following: when you reach the threshold, you start "to double the speedy step increment each encoder cycle/step". You may limit the maximum to 2^8 for example.. So the step's increments after the threshold triggers will be:
Code: [Select]
en.cycle - step increment size
..   1
..   1
..   1
threshold kicks
1.  100
2.  200
3.  400
..
8.  256000
9.  256000
10. 256000
threshold off
11.  1
12.  1
..

So a fast kick into the dial will increment/decrement by millions (based on how long you keep with fast rotating the knob).. For example my DDS VFO has 1Hz increment per encoder cycle/step normally, with 5-6 fast and "long enough" kicks into the dial I am able to tune from initial 1kHz up to to 60MHz...

kowalski

Thanks pito for the feedback.

That was a totally different number scale/scenario than what I thought. This is accelerated dialing and not just two steps as the current implementation ;-)

Fast dialing through approx. 60 MHz with slow dialing at 1 Hz is a real challenge. Two levels does not solve the problem very well. I must play around with the stepping strategy you suggest. Would like to express the "speed limit" in terms of the range of the data type given to the template class. Or just another parameter to the template (which is the easy way out).

Thanks again for take time to test the code.

Cheers!

pito

#111
Jun 11, 2013, 03:50 pm Last Edit: Jun 11, 2013, 05:00 pm by pito Reason: 1
Leave the stuff as is, just include the "doubling effect". That is it. With proper initial "speeds" step one may fine tune the effect.
Example:
You may use 1Hz as normal speed, and 10Hz as the speedy initial step (and limit 2^10). Long enough accelerated kick may last 20 encoder steps (with 36 total for example), so it increments by:
2^10 * 10 = 10240
plus
10 * 10240 = 102400, in total 112640.

During initial 10 steps you may see you are near the desired frequency already, so you will decelerate, below the threshold it switches to 1Hz step (or starts halving the steps) and you may fine tune.

The best approach would be to measure the time elapsed between the encoder cycles, and based on that the steps will be changed (the shorter time the higher step). That will create the nicest effect, I think.

PS: the routine with pic worked with an interrupt (each 250us, the tick), the encoder was serviced by the interrupt, it decreased an initial 10000 "step" by half each n-ticks (ie. 10), when no change at encoder's pins (or slow rotation) the "step" dropped down to 1 (the normal knob increment) during the "low activity", while when rotated fast the "step" had no chance to be halved down to 1, so the knob value was incremented/decremented with the current value of "step". So that made a very nice effect, the whole stuff was about 5 lines of code..

kowalski

This week Cosa takes a quantum leap forward with regard to wireless networking. Socket and abstract device driver classes are introduced together with basic support for clients and servers. The API is basically an object-oriented, event-driven, variant of standard sockets. This will allow easy integration with for instance the W5100 driver.





To demonstrate how Socket::Device is going to be used the NRF24L01+ device driver has been rewritten. With 32-bit addresses and 16-bit port numbers (as IP) it is possible to send datagrams point-to-point between any number of nodes (limited only by number of sockets in receiving node). The current implementation and examples for the NRF24L01+ device driver shows datagrams only. The next step is to introduce client-server connect-oriented sockets.





Above is a screen-shot with CosaNRFsensors example sketch sending sensor readings from analog pins, DHT11 and 1-Wire DS18B20 to CosaNRFmonitor which receives the datagrams and prints the contents. With ports and events writing wireless applications become easier. The below snippet from CosaNRFsensors shows device driver and socket binding to network address and port, and sending of datagrams with sequence number, battery voltage (in mV), and two analog pin readings. Name spaces are used in the sketch as it contains three different sensor and message types.

Code: [Select]

// NRF24L01+ Wireless communication using default pins(SPI, D9, D10, D2)
NRF24L01P nrf(0xc05a0001);

// Luminance and temperature sensor based on analog pins(A2, A3)
#include "Cosa/Pins.hh"
namespace LTB {
  const Socket::addr_t dest = { 0xc05a0002, 7000 };
  Socket socket(&nrf, 6000);
  AnalogPin luminance(Board::A2);
  AnalogPin temperature(Board::A3);
  uint16_t nr = 0;

  struct msg_t {
    uint16_t nr;
    uint16_t voltage;
    uint16_t luminance;
    uint16_t temperature;
  };

  void send_update()
  {
    msg_t msg;
    msg.nr = nr++;
    msg.luminance = luminance.sample();
    msg.temperature = temperature.sample();
    msg.voltage = AnalogPin::bandgap(1100);
    socket.send(&msg, sizeof(msg), dest);
  }
};


More details can be found in the preliminary on-line documentation, http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d4/d33/classSocket.html, and in the example directory, https://github.com/mikaelpatel/Cosa/tree/master/examples/Socket.

Cheers!

MarsWarrior


To demonstrate how Socket::Device is going to be used the NRF24L01+ device driver has been rewritten. With 32-bit addresses and 16-bit port numbers (as IP) it is possible to send datagrams point-to-point between any number of nodes (limited only by number of sockets in receiving node). The current implementation and examples for the NRF24L01+ device driver shows datagrams only. The next step is to introduce client-server connect-oriented sockets.

Altough my C++ knowledge is limited, I really like your project. It serves as a good inspiration point for some of my own sketches.

wrt the NRF24L01+, do you intend to support streaming also? The 32-byte buffer is much to small for me. I'm used to the RFM12B with its 66 byte (or more?) packetbuffer and would like to send & receive 128 byte packets (max). In other words: I need some sort of packetstreaming  8)

The COSA I/O buffer can be used to store the packet, but then the NRF24 should send this in multiple packets...

kowalski

#114
Jun 17, 2013, 03:26 pm Last Edit: Jun 17, 2013, 05:59 pm by kowalski Reason: 1

...do you intend to support streaming also? The 32-byte buffer is much to small for me. I'm used to the RFM12B with its 66 byte (or more?) packetbuffer and would like to send & receive 128 byte packets (max). In other words: I need some sort of packetstreaming  8)

Hi MarsWarrior. Thanks for your interest in this project. The Cosa network sub-system is work in progress. The goal is to hide as much of possible of the low level link layer from the application. And support a number of different Socket::Device's driver ranging from RF315/433, NRF24, Zigbee, BlueTooth to Ethernet (W5100). The NRF24L01+ device driver is the first one out.

For datagrams (connectionless communication) there will be an upper limit as this has to do with the amount of memory available for buffering. For the NRF24L01+ socket driver the limit is right now the hardware buffer size, 32 byte payload (minus the datagram header which is 8 bytes = 24 byte payload). The device driver is "raw" send and single package buffered receive.

There are several ways to approach datagram fragmentation. One approach would to use the NRF24L01+ internal FIFO and allow datagrams that could fill this queue. The max size would then be 3X32 minus header information and some additional sequence information (a byte). This would work for small devices such as ATtinyX4/X5 which have very limited SRAM (512 byte). For devices with more SRAM the issue of fragmentation is easier to solve with an intermediate buffer (such as IOBuffer).  

With the connection-oriented sockets (Cosa/Client socket) the NRF24L01+ driver does not add a header and the 32 byte payload is available to the application. The drawback is that the number of dynamic sockets are limited to the number of pipes in the device (total 6 pipes minus 1 used for datagrams = 5 dynamic sockets).

As the Cosa Socket interface is event driven and the device driver reads data from the hardware to a buffer in the device driver before calling the application (on_recv method). It is easy to receive any size payload into an internal buffer at the Socket before calling application code. Reassembly is a much easier problem to solve.

Later down the road there will be an integration between IOStream and Socket which will allow streaming. An example of how to do this is available for the Virtual Wire Interface (see VWIO).

Cheers!

MarsWarrior


Hi MarsWarrior. Thanks for your interest in this project. The Cosa network sub-system is work in progress. The goal is to hide as much of possible of the low level link layer from the application. And support a number of different Socket::Device's driver ranging from RF315/433, NRF24, Zigbee, BlueTooth to Ethernet (W5100). The NRF24L01+ device driver is the first one out.


I find your approach of building a complete system / infrastructure simply interesting because it is a very clean approach!
My approach is the opposite: re-use of existing libraries and modify them as less as possible and/or wrap them up a bit to create the required uniform interface/class.
As I'm using Nil/Chibi as RTOS, most changes are about changing (blocking) delays() with the more RTOS friendly versions...
Queues, Events & buffers are used to create very loosly coupled parts.

Quote

For datagrams (connectionless communication) there will be an upper limit as this has to do with the amount of memory available for buffering. For the NRF24L01+ socket driver the limit is right now the hardware buffer size, 32 byte payload (minus the datagram header which is 8 bytes = 24 byte payload). The device driver is "raw" send and single package buffered receive.

There are several ways to approach datagram fragmentation. One approach would to use the NRF24L01+ internal FIFO and allow datagrams that could fill this queue. The max size would then be 3X32 minus header information and some additional sequence information (a byte). This would work for small devices such as ATtinyX4/X5 which have very limited SRAM (512 byte). For devices with more SRAM the issue of fragmentation is easier to solve with an intermediate buffer (such as IOBuffer).  


The receiving side is indeed fairly simple by using an intermediate buffer. For the sending side I rely on the NRF24L01+ses auto-retry/auto-ack feature where I assume that packages always arrive, meaning I don't need difficult retry mechanisms and ACK/NACKing packages.

And since that assumption is not alwasy true :smiley-red:, I wondered what your approach would be  :) Since you are using the socket paradigm I assume you will try to mimic UDP sockets, but I have no idea how those work...

kowalski

#116
Jun 19, 2013, 09:59 am Last Edit: Jun 19, 2013, 01:19 pm by kowalski Reason: 1

I find your approach of building a complete system / infrastructure simply interesting because it is a very clean approach!
My approach is the opposite: re-use of existing libraries and modify them as less as possible and/or wrap them up a bit to create the required uniform interface/class.
As I'm using Nil/Chibi as RTOS, most changes are about changing (blocking) delays() with the more RTOS friendly versions...
Queues, Events & buffers are used to create very loosly coupled parts.

I guess that you are doing serious applications while I am trying to building frameworks through many rewrite and refactoring iterations. This is an attempt to get a set of components to "play together" and find "glue" that makes it easy to integrate them.

Many of the components in Cosa start off as you describe, wrapping an available design and are followed by "deep" study of the hardware manual and initial rewriting to C++ and cleaning code to a production level. A good example is the rewrite of VirtualWire. Then comes the fun part where I try to identify the internal components and start the refactoring process. Often adding interrupt and event handling. For VirtualWire this became the Codes and adding support for auto-acknowledgement and retransmission (as in the NRF24L01 hardware).

One of the more interesting design iterations in Cosa is the refactoring of the UART device driver. It started as a subset of the original Arduino code and ended up with a generic IOBuffer template class and a very small footprint UART device driver. It actually handles serial communication from ATtiny up to Arduino Mega's many ports. The UART became a simple interrupt handler and a delegation to the IOBuffers for input and output.

But all this takes time and rewriting/refactoring to evolve. To be able to go forward with more efficient frameworks and tooling I really need to see study different usage patterns and requirements. That's why feedback as yours is so important.

Quote

The receiving side is indeed fairly simple by using an intermediate buffer. For the sending side I rely on the NRF24L01+ses auto-retry/auto-ack feature where I assume that packages always arrive, meaning I don't need difficult retry mechanisms and ACK/NACKing packages.

And since that assumption is not alwasy true :smiley-red:, I wondered what your approach would be  :) Since you are using the socket paradigm I assume you will try to mimic UDP sockets, but I have no idea how those work...

For UDP style of sockets NRF24L01 transmit packets are too small and fragmentation is needed. The low-level retransmission and auto-ack is not always sufficient as the application still needs to handle what to do when the max number of retransmissions occur. At 2.4GHz there are bursts of noise that give that (e.g. micro-wave oven). Also typical high level retransmission will have timeouts in the range of 0.1-1 s while 24NRF01 retransmissions are less than 1 ms @ 2 Mbps. A totally different scale. For sensors with messages that fit into the payload (32 byte) NRF24 is perfect as is but for larger payloads and streaming a link level protocol is needed. I am working slowly upwards in this chain of support.

Cheers!

MarsWarrior

#117
Jun 19, 2013, 02:40 pm Last Edit: Jun 19, 2013, 03:25 pm by MarsWarrior Reason: 1

I guess that you are doing serious applications while I am trying to building frameworks through many rewrite and refactoring iterations. This is an attempt to get a set of components to "play together" and find "glue" that makes it easy to integrate them.


Well, because I'm using some nice RTOS, doesn't make my applications more serious than others. In fact, it is lazyness and simplicity that lead me to using these RTOSses: it makes making little things at a time easier: I do have a RF24 send and receive thread with a buffer as interface. I also have a sensor scanner thread and a request processing thread. They all have no knowledge of each other, but as you say "play together" using buffers/queues and events. This also enables me to write simple testcode without the need of the other functionality / threads.
The sensor scanner is a nice and simple example:
- First version dit only scan for digital inputs. If a sensor changed, the new value was put into a buffer and an buffer filled event is set;
- I made a second thread that changed one digital input each second;
- A third thread just waits for the buffer filled event, reads the buffer, and writes data to the serial port/console for me to check.

And as I'm currently refactoring the infrastructure stuff, nothing works together anymore at the moment... :smiley-red:

Quote

[...]
One of the more interesting design iterations in Cosa is the refactoring of the UART device driver. It started as a subset of the original Arduino code and ended up with a generic IOBuffer template class and a very small footprint UART device driver. It actually handles serial communication from ATtiny up to Arduino Mega's many ports. The UART became a simple interrupt handler and a delegation to the IOBuffers for input and output.

But all this takes time and rewriting/refactoring to evolve. To be able to go forward with more efficient frameworks and tooling I really need to see study different usage patterns and requirements. That's why feedback as yours is so important.


I liked the serial part: very simple and very clean. I used it as an example for some of my threads, as this approach fits an RTOS very good!

Quote

For UDP style of sockets NRF24L01 transmit packets are too small and fragmentation is needed. The low-level retransmission and auto-ack is not always sufficient as the application still needs to handle what to do when the max number of retransmissions occur. At 2.4GHz there are bursts of noise that give that (e.g. micro-wave oven). Also typical high level retransmission will have timeouts in the range of 0.1-1 s while 24NRF01 retransmissions are less than 1 ms @ 2 Mbps. A totally different scale. For sensors with messages that fit into the payload (32 byte) NRF24 is perfect as is but for larger payloads and streaming a link level protocol is needed. I am working slowly upwards in this chain of support.



My RF24 transmit thread wakes up every second at least to check if there is anything in the buffer (apart from the triggered events that there IS something in the buffer). The 1-second wake up (or time out on the semaphore) is used when transmission failed previously. So in fact perfecty in line with what you are saying...

kowalski

An update on the latest improvements and development of Cosa. The latest focus has been on improving the support for RTC, DS1307 and DS3231.

1. Added a new time/date structure for RTC devices (BCD representation).
2. Improved DS1307 I2C device driver.
3. Added support for DS3231 Extremely Accurate I2C-Integrated RTC/TCXO/Crystal. Support for alarms and reading the internal temperature sensor. Interrupt handler for alarms is not yet implemented.
4. Initial implementation of connection-oriented sockets for the NRF24L01P device driver. High level retransmission and socket/pipe disconnect is not yet fully implemented.

Cheers!

kowalski

#119
Jun 27, 2013, 08:24 pm Last Edit: Jun 29, 2013, 02:22 am by kowalski Reason: 1
An update on the latest improvements and development of Cosa. Some new hardware showed up in the mail.

1.  Driver for the PCF8574/PCF8574A Remote 8-bit I/O expander for I2C-bus with interrupt.
http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d1/da6/classPCF8574.html

2. Updated of LCD HD44780 driver to allow I/O adaption; Port and TWI modules mjkdz and DFRobot.
http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d8/df6/classHD44780_1_1IO.html

3. Clean up 1-wire (OWI) device driver support. Reducing foot-print; replaced print function with IOStream output operator to avoid usage of printf/printf_P.

4. Added support for concurrent temperature conversion request to OWI/DS18B20 device driver. Single command with no ROM address is issued. The devices may be parasite powered. Snippet from example sketch CosaDS18B20 with broadcast of convert request (12-bit and parasite power mode), read scratch pad and print of results from three devices.
Code: [Select]

OWI owi(Board::D7);
DS18B20 outdoors(&owi);
DS18B20 indoors(&owi);
DS18B20 basement(&owi);
...
void loop()
{
 ...
 DS18B20::convert_request(&owi, 12, true);
 indoors.read_scratchpad();
 outdoors.read_scratchpad();
 basement.read_scratchpad();
 trace << PSTR("indoors = ") << indoors
<< PSTR(", outdoors = ") << outdoors
<< PSTR(", basement = ") << basement
<< endl;
 ...
}

Typical output:
Code: [Select]
indoors = 24.75, outdoors = 24.68, basement = 24.75

http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/da/dc6/classDS18B20.html#a02f7c06daf67bc2d4572298d52e075cd

5. Refactoring of RTC DS1307/DS3231 control and status register definitions (bit-field struct introduced). Full support for reading and writing to DS1307 NV SRAM (56 bytes).
http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d8/da8/classDS1307.html
http://dl.dropboxusercontent.com/u/993383/Cosa/doc/html/d7/d49/DS3231_8hh_source.html#l00148

Cheers!

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