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Wall Clock Controller - PIC 16F877A

sku: WIG-00735

Description: The Wall Clock Controller from Spark Fun Electronics. This board was specifically developed to control the 24" Wall Clock project. It is a very good demonstration on how to use decoders and drivers to control a very large number of IO lines. Board can be used to control up to 42 devices. Each device can use up to 500mA of current!

The board comes fully tested assembled as shown. If you are planning on displaying GPS time, we recommend you also purchase the Lassen iQ GPS receiver. Board contains the PIC 16F877A TQFP with pre-installed serial boot loader, RS232 connection for debugging and programming, and 20MHz oscillator, and 32.768kHz RTC oscillator circuitry. Three general input switches are available: labeled 'Up', 'Down', and 'Select', they can be configured for any use. With the external 32kHz oscillator, this board can be used very accurately as a clock without the need for GPS.

Board controls 6 RJ45 ports with 7 output channels per port, and one raw-voltage feed line (8 total wires per jack). Each jack accepts an RJ45 cable (also known as Ethernet or Cat-5, Cat-5e, Cat-6, etc).  Each channel uses a Binary-Coded-Decimal decoder (part #: 74HC4511) to decode the binary number into a 7-segment display. These 7 channels are then controlled through a ULN2003 7-channel driver. For each individual RJ45 port, you can sink 500mA on 7 channels. This means you can control 6 * 7 or 42 different devices - each of which can use up to 500mA! We used this massive power to control 42 different LED light bars to create the giant GPS Wall Clock.

We provide example C code only. The example code will show you how to:

• Parse the incoming GPS strings from the Lassen iQ
• Output binary numbers to individual channels
• Read the input switches
• Report status over RS232 Serial

Documents: Wall Clock Controller Schematic, Driver Schematic, ULN2003A, 74HC4511

Software: Example Firmware