From 2fe8bebc6ce464afadef2403a8331031e16c5a5d Mon Sep 17 00:00:00 2001
From: David Shah <dave@ds0.me>
Date: Mon, 30 Nov 2020 08:59:04 +0000
Subject: nexus: Update docs and CMake

Signed-off-by: David Shah <dave@ds0.me>
---
 docs/nexus.md | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 docs/nexus.md

(limited to 'docs')

diff --git a/docs/nexus.md b/docs/nexus.md
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+# nextpnr-nexus notes
+
+### Constraints
+
+Currently the following PDC constraint styles are supported for IO constraints:
+
+```
+ldc_set_location -site {G13} [get_ports gsrn]
+ldc_set_port -iobuf {IO_TYPE=LVCMOS33} [get_ports {led[0]}]
+```
+
+Timing constraints are currently ignored, but should be expected to be supported soon.
+
+### Command Line
+
+A full device name is specified on the command line. It should be postfixed with 'ES' if using an engineering sample device to ensure correct use of the ES IDCODE.
+
+```
+--device LIFCL-40-9BG400CES
+```
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