ws2812 vs gpio: down the AND gate "later"

Right now, the ws2812 driver doesn't wait for the bit stream to return
control to Lua, so rather than immediately kick the AND gate off, set up
a timer to do it "soon".  This is not really the right fix, since it
leaves the AND gate high for a long while, but it works well enough I
suppose.

diff --git a/init2.lua b/init2.lua
index df282518ad4af8d2e656d8ee59b5b9fd44e96f33..44f752796f3c786193eb2a9f5db96162fb6953ae 100644 (file)
--- a/init2.lua
+++ b/init2.lua
@@ -35,6 +35,8 @@ end)
 ws2812.init(ws2812.MODE_SINGLE)     -- uses GPIO2
 i2c.setup(0,2,1,i2c.SLOW)           -- init i2c as per silk screen (GPIO4, GPIO5)
 
+local inhtmr = tmr.create()
+
 -- and now we get to the lamp stuff
 remotefb = ws2812.newBuffer(32,3)
 ledfb = remotefb -- points at whichever buffer is appropriate to draw
@@ -60,7 +62,11 @@ function dodraw()
     else
       gpio.write(3,gpio.HIGH) ws2812.write(ledfb)
     end
-    gpio.write(3,gpio.LOW)
+    -- Kick the inhibit timer to turn off the AND gate in 2 msec.  That should
+    -- be ample time to drain the serial UART.  If we get here again, we'll end
+    -- up resetting the timer's firing time, making this something like a
+    -- watchdog.  Hopefully we won't crash in the interim.
+    inhtmr:alarm(2,tmr.ALARM_SINGLE,function() gpio.write(3,gpio.LOW) end)
   end
 end