From dbe7943b1b1267aaa5a92821236055a7b61f04a0 Mon Sep 17 00:00:00 2001
From: Thomas White <taw@physics.org>
Date: Sun, 7 Jun 2020 19:10:39 +0200
Subject: Fix addressing

---
 guile/nanolight/fixture.scm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/guile/nanolight/fixture.scm b/guile/nanolight/fixture.scm
index ff45c22..0c67975 100644
--- a/guile/nanolight/fixture.scm
+++ b/guile/nanolight/fixture.scm
@@ -190,7 +190,8 @@
           ;; Set the value in the DMX array
           (u8vector-set!
             (assq-ref universes universe)
-            addr (round-dmx value)))
+            (- addr 1)                         ; u8vector-set indexing starts from zero
+            (round-dmx value)))
 
         ;; Scan out all fixtures
         (for-each (lambda (fix)
-- 
cgit v1.2.3