--- /dev/null
+(use-modules (ice-9 rdelim)
+ (ice-9 match)
+ (ice-9 receive)
+ (srfi srfi-1)
+ (ice-9 format))
+
+(system "stty -F /dev/ttyACM0 cs8 115200 ignbrk -brkint -icrnl -imaxbel -opost -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke noflsh -ixon -crtscts")
+
+(set! *random-state* (random-state-from-platform))
+
+(define out (open-file "/dev/ttyACM0" "w0+"))
+
+(define pi 3.14159)
+
+(define (deg->rad degrees)
+ (* degrees (/ pi 180)))
+
+(define (hsv->rgb h s v)
+ (let* ((chroma (* v s))
+ (hue' (/ h (/ pi 3)))
+ (x (* chroma (- 1 (abs (- (euclidean-remainder hue' 2) 1)))))
+ (m (- v chroma)))
+ (receive (r₁ g₁ b₁)
+ (case (inexact->exact (floor hue'))
+ ((0) (values chroma x 0))
+ ((1) (values x chroma 0))
+ ((2) (values 0 chroma x))
+ ((3) (values 0 x chroma))
+ ((4) (values x 0 chroma))
+ ((5) (values chroma 0 x)))
+ (values (+ r₁ m) (+ g₁ m) (+ b₁ m)))))
+
+;; (define ts (make-termios-struct))
+;; ;; Get the current setings of the serial-device.
+;; (tc-get-attr! out ts)
+;; (cf-set-speed! ts termios-B9600)
+;; (tc-set-attr out ts)
+
+(sleep 3)
+
+(define tick-increment (/ (* 2 pi) (* 360 1)))
+
+(define (random-ticks n) (* tick-increment (random n)))
+
+(define last-pulse (car (gettimeofday)))
+
+(let loop ((tick 0)
+ (saturation 0))
+ (format #t "~A " saturation)
+ (let ((h (euclidean-remainder tick (* 2 pi))))
+ (receive (r g b)
+ (hsv->rgb h (or 0.9 (- 1.0 (* (min saturation 10) 0.1))) 1)
+ (let ((r' (inexact->exact (round (* r 255))))
+ (g' (inexact->exact (round (* g 255))))
+ (b' (inexact->exact (round (* b 255)))))
+
+#;
+ (format #t "~A ~A ~A -> ~A ~A ~A~%" h 1 1 r' g' b')
+ (format out "~A,~A,~A,0~c" r' g' b' #\return)
+ (format out "~A,~A,~A,1~c" r' g' b' #\return)
+ #;(display (read-line out))))
+ (usleep 450000)
+ (loop (+ tick-increment tick)
+ (if (> (- (car (gettimeofday)) last-pulse) 1)
+ (begin (set! last-pulse (car (gettimeofday)))
+ 8)
+ (if (= saturation 0) 0 (1- saturation))))))
+
+#;
+(let loop ((rt (random-ticks 128))
+ (bt (random-ticks 128))
+ (gt (random-ticks 128)))
+ (let ((r (inexact->exact (truncate (* 128 (+ 1 (sin rt))))))
+ (g (- 256 (inexact->exact (truncate (* 128 (+ 1 (cos gt)))))))
+ (b (inexact->exact (truncate (* 128 (+ 1 (sin bt)))))))
+ #;(format #t "~A ~A ~A~%" r g b)
+ (format out "~A,~A,~A,4~c" r g b #\return)
+ (display (read-line out))
+ (usleep 45000)
+ (loop (+ rt (* tick-increment (1+ (random 3))))
+ (+ gt (* tick-increment (1+ (random 3))))
+ (+ bt (* tick-increment (1+ (random 3)))))))
+