From 48ba63ba1180671fd4bd87cbd5d9313cdb4a012a Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Wed, 30 Oct 2019 21:14:35 +1100
Subject: [PATCH] AP_Scripting: added example script for LEDs

show LED values based on roll
---
 libraries/AP_Scripting/examples/LED_roll.lua | 85 ++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 libraries/AP_Scripting/examples/LED_roll.lua

diff --git a/libraries/AP_Scripting/examples/LED_roll.lua b/libraries/AP_Scripting/examples/LED_roll.lua
new file mode 100644
index 0000000000..a997c2b5a3
--- /dev/null
+++ b/libraries/AP_Scripting/examples/LED_roll.lua
@@ -0,0 +1,85 @@
+--[[
+Script to control LED strips based on the roll of the aircraft. This is an example to demonstrate
+the LED interface for WS2812 LEDs
+--]]
+
+--[[
+for this demo we will use a single strip with 30 LEDs
+--]]
+local num_leds = 30
+
+--[[
+ use SERVOn_FUNCTION 94 for LED. We can control up to 16 separate strips of LEDs
+ by putting them on different channels
+--]]
+local chan = SRV_Channels:find_channel(94)
+
+if not chan then
+    gcs:send_text(6, string.format("LEDs: channel not set"))
+    return
+end
+
+-- find_channel returns 0 to 15, convert to 1 to 16
+chan = chan + 1
+
+gcs:send_text(6, string.format("LEDs: chan=" .. tostring(chan)))
+
+-- initialisation code
+serialLED:set_num_LEDs(chan,  num_leds)
+
+-- constrain a value between limits
+function constrain(v, vmin, vmax)
+   if v < vmin then
+      v = vmin
+   end
+   if v > vmax then
+      v = vmax
+   end
+   return v
+end
+
+--[[
+Table of colors on a rainbow, red first
+--]]
+local rainbow = {
+  { 255, 0, 0 },
+  { 255, 127, 0 },
+  { 255, 255, 0 },
+  { 0,   255, 0 },
+  { 0,   0,   255 },
+  { 75,  0,   130 },
+  { 143, 0,   255 },
+}
+
+--[[
+Function to set a LED to a color on a classic rainbow spectrum, with v=0 giving red
+--]]
+function set_Rainbow(chan, led, v)
+  local num_rows = #rainbow
+  local row = math.floor(constrain(v * (num_rows-1)+1, 1, num_rows-1))
+  local v0 = (row-1) / (num_rows-1)
+  local v1 = row / (num_rows-1)
+  local p = (v - v0) / (v1 - v0)
+  r = math.floor(rainbow[row][1] + p * (rainbow[row+1][1] - rainbow[row][1]))
+  g = math.floor(rainbow[row][2] + p * (rainbow[row+1][2] - rainbow[row][2]))
+  b = math.floor(rainbow[row][3] + p * (rainbow[row+1][3] - rainbow[row][3]))
+  serialLED:set_RGB(chan, uint32_t(1 << led), r, g, b)
+end
+
+--[[
+We will set the colour of the LEDs based on roll of the aircraft
+--]]
+function update_LEDs()
+  local roll = constrain(ahrs:get_roll(), math.rad(-60), math.rad(60))
+
+  for led = 0, num_leds-1 do
+    local v  = constrain(0.5 + 0.5 * math.sin(roll * (led - num_leds/2) / (num_leds/2)), 0, 1)
+    set_Rainbow(chan, led, v)
+  end
+  serialLED:send()
+
+  return update_LEDs, 20 -- run at 50Hz
+end
+
+return update_LEDs, 1000
+