Add instructions, non-working firmware

Build.sh

@@ -28,7 +28,7 @@ mv cakelisp_cache/Keypad/Keypad.cake.c cakelisp_cache/Keypad/Keypad.ino || exit
 # mv cakelisp_cache/Keypad/LowPower.c cakelisp_cache/Keypad/LowPower.ino || exit $?
 
 /media/macoy/Preserve/Programs/arduino-cli_0.29.0-rc.1_Linux_64bit/arduino-cli --no-color \
-	compile -b arduino:avr:uno ./cakelisp_cache/Keypad/Keypad.ino || exit $?
+	compile -b rp2040:rp2040:adafruit_kb2040 ./cakelisp_cache/Keypad/Keypad.ino || exit $?
 
 /media/macoy/Preserve/Programs/arduino-cli_0.29.0-rc.1_Linux_64bit/arduino-cli --no-color \
-	upload -b arduino:avr:uno --port /dev/ttyACM0 ./cakelisp_cache/Keypad || exit $?
+	upload -b rp2040:rp2040:adafruit_kb2040 --port /dev/ttyACM0 ./cakelisp_cache/Keypad || exit $?

ReadMe.org

@@ -1,3 +1,20 @@
 #+title: Keyboards
 
 This is my dumping ground for various physical keyboard firmware and designs.
+
+* Building and running
+Follow [[https://learn.adafruit.com/adafruit-kb2040/arduino-ide-setup][Arduino IDE Setup]].
+In short:
+- Get Arduino IDE (and Arduino Console while you're at it)
+- Add ~https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json~ to ~Preferences > Additional Boards Manager URLs~
+- Search for ~RP2040~ in Board Manager and install the ~Raspberry Pi Pico/RP2040 by Earle F Philhower, III~
+The console board name is ~rp2040:rp2040:adafruit_kb2040~.
+
+Run ~Build.sh~.
+
+** Observing output
+#+BEGIN_SRC sh
+  screen /dev/ttyACM0 115200
+#+END_SRC
+*** Killing screen sessions
+~Ctrl + a~ then ~k~

src/Keypad.cake

@@ -9,5 +9,41 @@
 
 (import "CHelpers.cake")
 
-(defun main (&return int)
-  (return 0))
+(var column-pins (array (const int)) ;; receives power
+  (array 29 28 27 26)) ;; A3 A2 A1 A0
+(var row-pins (array (const int)) ;; samples
+  (array 2 3 4 5 6)) ;; 2 3 4 5 6
+
+(var matrix (array 4 (array 5 int)) (array 0))
+
+(defun setup ()
+  (pinMode LED_BUILTIN OUTPUT)
+  (each-item-in-array column-pins column pin int
+    (pinMode pin OUTPUT)
+    (digitalWrite pin LOW))
+  (each-item-in-array row-pins row pin int
+    (pinMode pin INPUT_PULLUP))
+  (call-on begin Serial 115200)
+  (call-on println Serial "Keypad started up"))
+
+(defun scan-matrix ()
+  (each-item-in-array column-pins column col-pin int
+    (digitalWrite col-pin HIGH)
+    (defer (digitalWrite col-pin LOW))
+    ;; This should be way faster in production
+    (delay 30)
+    (each-item-in-array row-pins row row-pin int
+      (set (at column row matrix) (not (digitalRead row-pin))))))
+
+(defun loop ()
+  (scan-matrix)
+  (call-on println Serial "\n-------")
+  (each-in-range 2 column
+    (each-in-range 2 row
+      (when (at column row matrix)
+        (call-on println Serial "----")
+        (call-on println Serial column)
+        (call-on println Serial row)
+        (call-on println Serial "ON"))))
+  ;; wait for a bit
+  (delay 500))