1 files changed, 12 insertions, 0 deletions

diff --git a/docs/extra-build-config.md b/docs/extra-build-config.md
index 843247a..d92cf4e 100644
--- a/docs/extra-build-config.md
+++ b/docs/extra-build-config.md
@@ -261,6 +261,18 @@ In order to use Pican2 CAN module, set the following variables:
 
 See: <http://skpang.co.uk/catalog/pican2-canbus-board-for-raspberry-pi-23-p-1475.html>
 
+## Enable infrared
+
+Users who want to enable infrared support, for example for using LIRC (Linux
+Infrared Remote Control), have to explicitly set in local.conf:
+
+    ENABLE_IR = "1"
+
+This will add device tree overlays gpio-ir and gpio-ir-tx to config.txt.
+Appropriate kernel modules will be also included in the image. By default the
+GPIO pin for gpio-ir is set to 18 and the pin for gpio-ir-tx is 17. Both pins
+can be easily changed by modifying variables `GPIO_IR` and `GPIO_IR_TX`.
+
 ## Manual additions to config.txt
 
 The `RPI_EXTRA_CONFIG` variable can be used to manually add additional lines to