Tick Tock
The Raspberry Pi has many amazing features, but it is missing a clock. We'll show how to add a real-time clock chip to your Pi.
Lead Image © Joerg Michael Gehrke, 123RF.com
The Raspberry Pi has many amazing features, but it is missing a clock. We'll show how to add a real-time clock chip to your Pi.
Whether the frugality concerns that played such a central role in designing the Raspberry Pi led to the decision to omit a clock – a built-in feature on most personal computers – is not clear. Whatever the reason, the Rasp Pi has no clock with which to tell time or set an alarm, and this omission has proven inconvenient for many Rasp Pi users.
Many tasks you might want to assign to the Raspberry Pi require an on-board clock. For example, many network services require accurate system time, and some embedded systems require timed remote bootup or intricate synchronization with other devices. All you need to retrofit your Raspberry Pi with a clock is a circuit board you solder yourself, a short C program, and a bit of adjustment to the system.
In this article I describe how to outfit your Raspberry Pi with a Real-Time Clock (RTC) chip. An RTC chip has an integrated quartz oscillator used for incrementing a counter. The computer can then convert the oscillator output to a human-readable time of day and date. In this case, I'll use the MCP79410, an RTC chip form Microchip Technology [1]. The MCP79410 offers two independent alarm settings that you can set for up to one year into the future.
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Pages: 8
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