yosys

History

Marcin Kościelnicki f4c62f33ac Add clock buffer insertion pass, improve iopadmap. A few new attributes are defined for use in cell libraries: - iopad_external_pin: marks PAD cell's external-facing pin. Pad insertion will be skipped for ports that are already connected to such a pin. - clkbuf_sink: marks an input pin as a clock pin, requesting clock buffer insertion. - clkbuf_driver: marks an output pin as a clock buffer output pin. Clock buffer insertion will be skipped for nets that are already driven by such a pin. All three are module attributes that should be set to a comma-separeted list of pin names. Clock buffer insertion itself works as follows: 1. All cell ports, starting from bottom up, can be marked as clock sinks (requesting clock buffer insertion) or as clock buffer outputs. 2. If a wire in a given module is driven by a cell port that is a clock buffer output, it is in turn also considered a clock buffer output. 3. If an input port in a non-top module is connected to a clock sink in a contained cell, it is also in turn considered a clock sink. 4. If a wire in a module is driven by a non-clock-buffer cell, and is also connected to a clock sink port in a contained cell, a clock buffer is inserted in this module. 5. For the top module, a clock buffer is also inserted on input ports connected to clock sinks, optionally with a special kind of input PAD (such as IBUFG for Xilinx). 6. Clock buffer insertion on a given wire is skipped if the clkbuf_inhibit attribute is set on it.		2019-08-13 00:16:38 +02:00
..
README	Add a simple example for Spartan 6	2019-07-24 18:59:03 +02:00
example.ucf	Add a simple example for Spartan 6	2019-07-24 18:59:03 +02:00
example.v	Add a simple example for Spartan 6	2019-07-24 18:59:03 +02:00
run.sh	Add a simple example for Spartan 6	2019-07-24 18:59:03 +02:00
run_yosys.ys	Add clock buffer insertion pass, improve iopadmap.	2019-08-13 00:16:38 +02:00

README

A simple example design, based on the Numato Labs Mimas V2 board
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This example uses Yosys for synthesis and Xilinx ISE
for place&route and bit-stream creation.

To synthesize:
  bash run.sh