From 1e3034c40f8db6534c9dbd271f429d7ae89d14cf Mon Sep 17 00:00:00 2001 From: Nathaniel Wesley Filardo Date: Sun, 3 Sep 2017 00:52:14 -0400 Subject: [PATCH] Add note about AND gate to README --- README.rst | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/README.rst b/README.rst index bd54bd1..91f5490 100644 --- a/README.rst +++ b/README.rst @@ -3,9 +3,12 @@ Remote Touch Lamp ################# This somewhat sizable project is a re-implementation of -``http://filimin.com/`` of sorts. It speaks MQTT and uses a CAP1188 for +http://filimin.com/ of sorts. It speaks MQTT and uses a CAP1188 for local touch sensing. Display is via a grid of so-called "NeoPixel" LEDs. +Motivation, pictures, and additional discussion can be found at +http://www.ietfng.org/nwf/ee/purple-lamp.html + Hardware V1 ########### @@ -51,6 +54,22 @@ stack the RGB array atop the ESP8266 and hookup via the Doubler's female headers, or do away with the Doubler entirely and hook the male pins on the ESP8266, etc. +Revision 1.1 +============ + +An AND gate (actually, a 7408) was added to gate serial access to the +WS2812. On boot, the ESP8266 emits debugging information to its alternate +serial console, which is also the ws2812 data source. This results in some +blindingly bright light when the machine boots or crashes. The AND gate +effectively prevents the chip from writing to the ws2812 matrix unless +another GPIO is pulled high as well. + +The WS2812 LED array from AdaFruit allows for one of many pins to be +selected for the WS2812 input line; as the ESP8266 does not use all of the +possible I/O lines of the Feather design, a free signal (N/C to the ESP8266 +Feather Huzzah CPU board) was chosen instead and the AND gate's output +routed back into the stack on this line. + ESP IO ###### @@ -59,6 +78,8 @@ The various boards are interfaced as follows: +--------------+----------------------------------------------------------+ | ESP GPIO Pin | Function | +--------------+----------------------------------------------------------+ +| 0 | WS2812 AND-gate input (see above) | ++--------------+----------------------------------------------------------+ | 2 | WS2812 serial shift out (to LED array input) | +--------------+----------------------------------------------------------+ | 4 | I2C SDA pin (to CAP1188, optional expansion) | -- 2.50.1