From 3d6f55104b07ed5d04cc3cc8a6df399241c9e32e Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sun, 22 May 2016 06:53:18 -0700
Subject: [PATCH] coredevice/TCA6424A: convert 'outputs' value to little
 endian. Closes #437

---
 RELEASE_NOTES.rst       | 7 +++++++
 artiq/coredevice/i2c.py | 7 ++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/RELEASE_NOTES.rst b/RELEASE_NOTES.rst
index 12f45629f..6a6269ab6 100644
--- a/RELEASE_NOTES.rst
+++ b/RELEASE_NOTES.rst
@@ -42,6 +42,13 @@ unreleased [2.x]
   takes into account the repository revision field.
 
 
+1.1 (unreleased)
+----------------
+
+* TCA6424A.set converts the "outputs" value to little-endian before programming
+  it into the registers.
+
+
 1.0
 ---
 
diff --git a/artiq/coredevice/i2c.py b/artiq/coredevice/i2c.py
index fb37a2aa6..da3fa6269 100644
--- a/artiq/coredevice/i2c.py
+++ b/artiq/coredevice/i2c.py
@@ -108,5 +108,10 @@ class TCA6424A:
 
         A bit set to 1 means the TTL is an output.
         """
+        outputs_le = (
+            ((outputs & 0xff0000) >> 16) |
+            (outputs & 0x00ff00) |
+            (outputs & 0x0000ff) << 16)
+
         self._write24(0x8c, 0)  # set all directions to output
-        self._write24(0x84, outputs)  # set levels
+        self._write24(0x84, outputs_le)  # set levels