From afe43d0bdc7affb7a7b7d5240dac3e247d57a209 Mon Sep 17 00:00:00 2001 From: ryansuchocki Date: Thu, 26 Feb 2015 11:30:20 +0000 Subject: [PATCH] Adding max7 example --- examples/max7.ms | 100 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 examples/max7.ms diff --git a/examples/max7.ms b/examples/max7.ms new file mode 100644 index 0000000..c592702 --- /dev/null +++ b/examples/max7.ms @@ -0,0 +1,100 @@ +;; A microscheme library for controlling MAX7219 and MAX7221 chips. +;; These are serially-interfaced 8x8 multiplex drivers, commonly used +;; for LED arrays and 7-segment displays. + +;; ==================== Internal procedures ==================== +;; (These should not be called directly) + +(define (shift-out-bits data-pin clock-pin data n) + (set-pin data-pin (begin data (asm "ROL CRSh" "ROL CRSh"))) + (low (high clock-pin)) + (if (zero? n) + #t + (begin + (shift-out-bits data-pin clock-pin (begin data (asm "LSL CRSl" "ROL CRSh")) (- n 1))))) + +(define (noops data-pin clock-pin n) + (if (zero? n) + #t + (begin + (shift-out-bits data-pin clock-pin #x0000 15) + (noops data-pin clock-pin (- n 1))))) + +(define (shift-out chip index data) + (let ((data-pin (vector-ref chip 0)) + (clock-pin (vector-ref chip 1)) + (latch-pin (vector-ref chip 2)) + (num (vector-ref chip 3))) + (low latch-pin) + (noops data-pin clock-pin (- (- num index) 1)) + (shift-out-bits data-pin clock-pin data 15) + (noops data-pin clock-pin index) + (high latch-pin))) + +;; ==================== External procedures ==================== +;; (These should be called directly) + +;; Each chip features one data-in pin and one data-out pin, so that +;; up to 8 chips can be cascaded together, sharing a single data line. +;; Each cascade of chips must be initialised using def-max7. The result +;; is an object used to reference a particular cascade of chips, when it +;; comes to sending data. + +(define (def-max7 data-pin clock-pin latch-pin num) + (vector + (low (output data-pin)) + (low (output clock-pin)) + (high (output latch-pin)) + num)) + +(define (digit chip index dig val) (shift-out chip index (+ (* dig #x100) val))) +(define (decode chip index m) (shift-out chip index (+ #x0900 m))) +(define (intensity chip index x) (shift-out chip index (+ #x0A00 x))) +(define (scan-limit chip index n) (shift-out chip index (+ #x0B00 n))) +(define (show chip index state) (shift-out chip index (if state #x0C01 #x0C00))) +(define (test chip index state) (shift-out chip index (if state #x0F01 #x0F00))) + + +;; ======================= Example Usage ======================= + +; (include "working/max7.ms") + +; We have 2 max7219 chips cascaded together, on pins 10, 11 and 12 +; (define lcd (def-max7 10 11 12 2)) +; ... connected to a 16-digit 7-segment display! + +; We set both chips to decode-mode on all digits: +; So that we can send numeric characters directly (in BCD) +; (decode lcd 0 #xFF) +; (decode lcd 1 #xFF) + +; Set the intensity to maximum on both chips: +; (intensity lcd 0 #x0F) +; (intensity lcd 1 #x0F) + +; Enable all digits on both chips: +; (scan-limit lcd 0 #x07) +; (scan-limit lcd 1 #x07) + +; Make sure both chips are out of 'shutdown' mode: +; (show lcd 0 #t) +; (show lcd 1 #t) + +; Now we display the number '0102030405060708' + +; (digit lcd 0 1 0) +; (digit lcd 0 2 1) +; (digit lcd 0 3 0) +; (digit lcd 0 4 2) +; (digit lcd 0 5 0) +; (digit lcd 0 6 3) +; (digit lcd 0 7 0) +; (digit lcd 0 8 4) +; (digit lcd 1 1 0) +; (digit lcd 1 2 5) +; (digit lcd 1 3 0) +; (digit lcd 1 4 6) +; (digit lcd 1 5 0) +; (digit lcd 1 6 7) +; (digit lcd 1 7 0) +; (digit lcd 1 8 8)