Author: wmb Date: Wed Jul 18 23:45:40 2012 New Revision: 3070 URL: http://tracker.coreboot.org/trac/openfirmware/changeset/3070
Log: OLPC accelerometer demo - added "level" command to implement a clinometer precise to 0.1 degrees up to 45 degrees.
Modified: cpu/arm/olpc/roller.fth
Modified: cpu/arm/olpc/roller.fth ============================================================================== --- cpu/arm/olpc/roller.fth Wed Jul 18 09:35:51 2012 (r3069) +++ cpu/arm/olpc/roller.fth Wed Jul 18 23:45:40 2012 (r3070) @@ -19,7 +19,7 @@
d# 8 value #fraction-bits : fraction* ( -- ) * #fraction-bits >>a ; -: 1/2 ( -- n ) 1 #fraction-bits 1- lshift ; +: 1/2 ( -- n ) 1 #fraction-bits 1- lshift ; : >fraction ( n -- fraction ) #fraction-bits lshift ; : a/b>fraction ( num denom -- fraction ) swap #fraction-bits lshift swap / ;
@@ -80,13 +80,29 @@ d# 20 constant ball-radius d# 40 constant ball-diameter
-: maxx ( -- n ) screen-wh drop ball-diameter - >fraction ; -: maxy ( -- n ) screen-wh nip ball-diameter - >fraction ; +: maxx-raw ( -- n ) screen-wh drop ball-diameter - ; +: maxy-raw ( -- n ) screen-wh nip ball-diameter - ; + +: maxx ( -- n ) maxx-raw >fraction ; +: maxy ( -- n ) maxy-raw >fraction ; d# 400 >fraction constant maxz
: 3swap ( x1 y1 z1 x2 y2 z2 -- x2 y2 z2 x1 y1 z1 ) 5 roll 5 roll 5 roll ; : 3over ( x1 y1 z1 x2 y2 z2 -- x2 y2 z2 x1 y1 z1 ) 5 pick 5 pick 5 pick ;
+\ This is a simple approximation for the magnitude of a 3-vector +\ - largest component plus 1/3 the sum of the two smaller components. +\ It works surprisingly well, especially since we use it to estimate +\ drag, which is a complicated phenomenon for which the formula is +\ only an approximation anyway. + +: xyz-magnitude ( x y z -- magnitude ) + rot abs rot abs rot abs + 2dup > if swap then ( x min-y,z max-y,z ) + rot 2dup > if swap then ( a b max ) + -rot + 3 / + ( magnitude ) +; + [ifdef] notdef 0 0 0 3value pos-b' \ New ball position 0 0 0 3value vel-l \ Laptop velocity @@ -107,19 +123,6 @@ vel-l damping xyz* xyz+ to vel-l ( ) ;
-\ This is a simple approximation for the magnitude of a 3-vector -\ - largest component plus 1/3 the sum of the two smaller components. -\ It works surprisingly well, especially since we use it to estimate -\ drag, which is a complicated phenomenon for which the formula is -\ only an approximation anyway. - -: xyz-magnitude ( x y z -- magnitude ) - rot abs rot abs rot abs - 2dup > if swap then ( x min-y,z max-y,z ) - rot 2dup > if swap then ( a b max ) - -rot + 3 / + ( magnitude ) -; - \ This is a coupling coefficient between the net velocity (laptop - ball) \ and the ball acceleration. It encapsulates various constant factors \ such as the drag coefficient and unit conversions. Its value is adjusted @@ -251,6 +254,93 @@ text-on ;
+: filtered-acceleration ( -- acc-x,y,z ) + 0 0 0 + d# 16 0 do net-acceleration xyz+ loop + 1 d# 16 a/b>fraction xyz* +; + +d# 573 constant deg*10/rad +d# 1460 value gravity +: .decidegrees ( degrees*10 -- ) + dup abs d# 450 > if ( degrees*10 ) + 0< if ." <-45" else ." >45" then + else + push-decimal + dup abs <# u# [char] . hold u#s swap sign u#> type + ." " + pop-base + then +; + +0 value xsq +0 value gsq + +: arcsin-step ( n -- n' ) deg*10/rad + xsq gsq */ ; +: arcsin*10 ( x -- degrees*10 ) + dup dup * to xsq ( x ) + gravity dup * to gsq ( x ) + \ Starting with this bias instead of 0 helps with roundoff error, + \ so the result is good to within 0.1 degree up to 45 degrees. + d# 7500 ( x n ) + arcsin-step d# 20 / ( x n' ) \ x^5 / 5! term + arcsin-step d# 06 / ( x n' ) \ x^3 / 3! term + deg*10/rad + ( x n' ) \ x term + gravity */ +; + +: x-center ( -- x ) screen-wh drop 2/ ; +: y-center ( -- y ) screen-wh nip 2/ ; + +: put-ball ( x y z -- ) 3dup pos-b redraw to pos-b ; +: put-centered ( offset-x offset-y z-size -- ) + >r ( x y r: z ) + swap x-center + 0 max maxx-raw min >fraction ( y x' r: z ) + swap y-center + 0 max maxy-raw min >fraction ( x' y' r: z ) + r> put-ball +; + +: show-center-mark ( -- ) + 0 set-fg x-center ball-radius + y-center ball-radius + d# 16 circleat +; + +0 0 0 3value cal-xyz +: update-angle ( -- ) + filtered-acceleration ( acc-x,y,z ) + cal-xyz xyz- drop ( x' y' ) + 0 0 at-xy + ." Degrees X " over arcsin*10 .decidegrees ." Y " dup arcsin*10 .decidegrees ( x' y' ) + swap 2/ swap 2/ + d# 0 put-centered + show-center-mark + \ ." X " rot 5 .r ." Y " swap 5 .r ." Z " 5 .r +; + +: ?zero ( -- ) + rotate-button? if + filtered-acceleration to cal-xyz + cal-xyz xyz-magnitude to gravity + 0 1 at-xy ." Zeroing" + begin rotate-button? 0= until + (cr ." " + then +; +: clinometer ( -- ) + init-accelerometer + init-ball + cursor-off + clear-drawing + d# 40 0 at-xy ." Rotate button zeroes" + begin + ?zero + ( update-laptop ) update-angle d# 50 ms + key? until + cursor-on +; +: level ( -- ) + clinometer +; + \ LICENSE_BEGIN \ Copyright (c) 2011 FirmWorks \
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