From f4c62f33ac56bc5725c44ad822e75d2387f98061 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Ko=C5=9Bcielnicki?= Date: Mon, 12 Aug 2019 15:57:43 +0000 Subject: 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. --- examples/mimas2/run_yosys.ys | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'examples') diff --git a/examples/mimas2/run_yosys.ys b/examples/mimas2/run_yosys.ys index b3204b1ca..b48877811 100644 --- a/examples/mimas2/run_yosys.ys +++ b/examples/mimas2/run_yosys.ys @@ -1,4 +1,3 @@ read_verilog example.v -synth_xilinx -top example -family xc6s -iopadmap -bits -outpad OBUF I:O -inpad IBUF O:I +synth_xilinx -top example -family xc6s -ise write_edif -pvector bra example.edif -- cgit v1.2.3