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Subversion Repositories rtcclock
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# Real Time Clock Core |
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Every FPGA project needs to start with a very simple core. Then, working from |
simplicity, more and more complex cores can be built until an eventual |
application comes from all the tiny details. |
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This real time clock began with one such simple core. All of the pieces to |
this clock are simple. Nothing is inherently complex. However, placing this |
clock into a larger FPGA structure requires a Wishbone bus, and being able |
to command and control an FPGA over a wishbone bus is an achievement in and |
of itself. Further, the clock produces outputs that can be used to strobe |
an interrupt line. Reading and processing that interrupt line requires |
a whole 'nother bit of logic and the ability to capture, recognize, and |
respond to interrupts. Hence, once you get a simple clock working, you have |
a lot working. |
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Included in this repository are several basic cores which can be |
used for this purpose: |
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- rtcclock: the original RTC Clock module. This was originally built for a Basys-3 board, and so it also has outputs suitable for commanding LEDs and a seven segment display. |
- rtclight: Just the basic RTC, with no LEDs or seven segment display output wires. |
- rtcgps: A real-time clock which can be used together with a cleaned-up GPS PPS, to keep the clock accurate at a subsecond level to the top of the second. Further work is required to get the clock to the correct second, but this will hold it to the correct subsecond interval. |