Time Machine
Semiconductor chips controlled by an I2C bus can be used in many applications. The PCF8583, an eight-pin clock and timer chip, is an interesting example.
Using the PCF8583 as a clock component on the I2C bus of the Raspberry Pi
Lead Image © pandavector, 123RF.com
The connection capabilities of the Raspberry Pi GPIO interface are often insufficient for large projects. The I2C bus offers a significant number of options for circumventing the limitations imposed by the standard interface. In this second part of the series on the I2C bus, I discuss how to use the bus to communicate with a clock and timer chip and provide a more detailed description of the PCF8583 microcontroller [1].
The PCF8583 (Figure 1) is a clock and calendar component that has 240 bytes of available storage. Frequently, the chip comes in a DIP 8 package. It only has one address line; therefore, you can have at most two of these components with allocated start addresses of 0xA0 and 0xA2 operating on one bus.
In this experiment, I used a field-effect transistor (FET) with an open drain for the interrupt or alarm output, which means it does not deliver a clean logic level without an additional external pull-up resistor. Also, the output is active low and accepts a maximum of 3mA. These qualities provide the means for a simple test setup with an LED on this connector. The data sheet contains more specific hardware details [2].
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