Improve the base pin, set up morse code flasher on feather 32u4

base/base.h

@@ -3,17 +3,36 @@
 #ifndef __BASE_H__
 #define __BASE_H__
 
+#define PIN_OUT 1
+#define PIN_IN  0
+
 typedef struct IO_PIN {
+    volatile uint8_t *ddr;
     volatile uint8_t *port;
-    uint8_t pin;
+    uint8_t addr;
 } io_pin_t;
 
+/*
+#define GPIOA(addr) (io_pin_t){ .ddr = &DDRA, .port = &PORTA, .addr = addr }
+#define GPIOB(addr) (io_pin_t){ .ddr = &DDRB, .port = &PORTB, .addr = addr }
+#define GPIOC(addr) (io_pin_t){ .ddr = &DDRC, .port = &PORTC, .addr = addr }
+#define GPIOD(addr) (io_pin_t){ .ddr = &DDRD, .port = &PORTD, .addr = addr }
+*/
+
+inline void set_pin_direction(io_pin_t *pin, int direction) {
+    if (direction == PIN_OUT) {
+        *(pin->ddr) |= _BV(pin->addr);
+    } else {
+        *(pin->ddr) &= ~(_BV(pin->addr));
+    }
+}
+
 inline void set_pin(io_pin_t *pin) {
-    *(pin->port) |= 1 << pin->pin;
+    *(pin->port) |= _BV(pin->addr);
 }
 
 inline void clear_pin(io_pin_t *pin) {
-    *(pin->port) &= 0xff ^ (1 << pin->pin);
+    *(pin->port) &= ~(_BV(pin->addr));
 }
 
 typedef struct RNG {

flake.nix

@@ -37,6 +37,36 @@
             '';
         };
 
+      packages."x86_64-linux"."morse-tx" =
+        let
+          pkgs = import nixpkgs { system = "x86_64-linux"; };
+          lib = pkgs.lib;
+          avr = pkgs.pkgsCross.avr.buildPackages;
+        in pkgs.stdenv.mkDerivation rec {
+          name = "morse-tx";
+          src = ./.;
+
+          includes = [ "base" "morse" ];
+
+          MCU = "atmega32u4";
+          CHIP_SELECT = "AVR_ATmego32u4";
+          F_CPU = "8000000";
+          CFLAGS = ''-O -finline-functions -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes -DF_CPU=${F_CPU} -std=gnu99 -D__${CHIP_SELECT}__=1 -mmcu=${MCU} -DAVR=1'';
+          INCLUDE_DIRS = lib.concatStringsSep " " (map (dir: "-I${src}/${dir}") includes);
+
+          buildPhase = ''
+            ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o morse.o -c ${src}/morse/morse.c
+            ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o main.o -c ${src}/morse_tx/main.c
+            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -o main.elf main.o morse.o
+            $OBJCOPY -O ihex main.elf main.hex
+            '';
+          installPhase = ''
+            mkdir $out
+            cp main.elf main.hex $out
+            '';
+        };
+
+
       devShell."x86_64-linux" =
         let
           pkgs = import nixpkgs { system = "x86_64-linux"; };

flash-feather

@@ -0,0 +1 @@
+avrdude -c avr109 -P /dev/ttyACM0 -p m32u4 -D -U flash:w:$1:i

morse/morse.c

@@ -0,0 +1,90 @@
+#include <util/delay.h>
+#include <string.h>
+#include "morse.h"
+
+/* TODO: all of this is a candidate for living in an EEPROM */
+typedef struct morse_codepoint {
+    size_t length;
+    uint8_t values[5];
+} morse_codepoint_t;
+
+const struct morse_codepoint MORSE[] = {
+    /* 0 */ { .length = 5, .values = { DASH, DASH, DASH, DASH, DASH } },
+    /* 1 */ { .length = 5, .values = { DOT,  DASH, DASH, DASH, DASH } },
+    /* 2 */ { .length = 5, .values = { DOT,  DOT,  DASH, DASH, DASH } },
+    /* 3 */ { .length = 5, .values = { DOT,  DOT,  DOT,  DASH, DASH } },
+    /* 4 */ { .length = 5, .values = { DOT,  DOT,  DOT,  DOT,  DASH } },
+    /* 5 */ { .length = 5, .values = { DOT,  DOT,  DOT,  DOT,  DOT } },
+    /* 6 */ { .length = 5, .values = { DASH, DOT,  DOT,  DOT,  DOT } },
+    /* 7 */ { .length = 5, .values = { DASH, DASH, DOT,  DOT,  DOT } },
+    /* 8 */ { .length = 5, .values = { DASH, DASH, DASH, DOT,  DOT } },
+    /* 9 */ { .length = 5, .values = { DASH, DASH, DASH, DASH, DOT } },
+    /* a */ { .length = 2, .values = { DOT,  DASH } },
+    /* b */ { .length = 4, .values = { DASH, DOT,  DOT,  DOT } },
+    /* c */ { .length = 4, .values = { DASH, DOT,  DASH, DOT } },
+    /* d */ { .length = 3, .values = { DASH, DOT,  DOT } },
+    /* e */ { .length = 1, .values = { DOT } },
+    /* f */ { .length = 4, .values = { DOT,  DOT,  DASH, DOT } },
+    /* g */ { .length = 3, .values = { DASH, DASH, DOT } },
+    /* h */ { .length = 4, .values = { DOT,  DOT,  DOT,  DOT } },
+    /* i */ { .length = 2, .values = { DOT,  DOT } },
+    /* j */ { .length = 4, .values = { DOT,  DASH, DASH, DASH } },
+    /* k */ { .length = 3, .values = { DASH, DOT,  DASH } },
+    /* l */ { .length = 4, .values = { DOT,  DASH, DOT,  DOT } },
+    /* m */ { .length = 2, .values = { DASH, DASH } },
+    /* n */ { .length = 2, .values = { DASH, DOT } },
+    /* o */ { .length = 3, .values = { DASH, DASH, DASH } },
+    /* p */ { .length = 4, .values = { DOT,  DASH, DASH, DOT } },
+    /* q */ { .length = 4, .values = { DASH, DASH, DOT,  DASH } },
+    /* r */ { .length = 3, .values = { DOT,  DASH, DOT } },
+    /* s */ { .length = 3, .values = { DOT,  DOT,  DOT } },
+    /* t */ { .length = 1, .values = { DASH } },
+    /* u */ { .length = 3, .values = { DOT,  DOT,  DASH } },
+    /* v */ { .length = 4, .values = { DOT,  DOT,  DOT,  DASH } },
+    /* w */ { .length = 3, .values = { DOT,  DASH, DASH } },
+    /* x */ { .length = 4, .values = { DASH, DOT,  DOT,  DASH } },
+    /* y */ { .length = 4, .values = { DASH, DOT,  DASH, DASH } },
+    /* z */ { .length = 4, .values = { DASH, DASH, DOT,  DOT } },
+};
+
+const struct morse_codepoint * morse_lookup(char val) {
+    size_t idx = -1;
+    if (val >= '0' && val <= '9') {
+        idx = val - '0';
+    } else if (val >= 'a' && val <= 'z') {
+        idx = (val - 'a') + 10;
+    } else if (val >= 'A' && val <= 'Z') {
+        idx = (val - 'A') + 10;
+    }
+    if (idx < 0) return NULL;
+    return &MORSE[idx];
+}
+
+void send_codepoint(io_pin_t *gpio, const struct morse_codepoint *codepoint) {
+    const uint8_t one = 1 << gpio->addr;
+    for (size_t i = 0; i < codepoint->length; i++) {
+        *gpio->port = *(gpio->port) | one;
+        if (codepoint->values[i] == DOT) {
+            _delay_ms(DOT * SCALE);
+        } else {
+            _delay_ms(DASH * SCALE);
+        }
+        *gpio->port = *(gpio->port) & ~one;
+        _delay_ms(DIVIDER * SCALE);
+    }
+    _delay_ms(INTERCHAR * SCALE);
+}
+
+void send_morse(io_pin_t *gpio, char *message) {
+    for (size_t i = 0; i < strlen(message); i++) {
+        if (message[i] == ' ') {
+            _delay_ms(INTERWORD * SCALE);
+        }
+        const struct morse_codepoint *codepoint = morse_lookup(message[i]);
+        if (codepoint != NULL) {
+            send_codepoint(gpio, codepoint);
+        }
+    }
+}
+
+

morse/morse.h

@@ -0,0 +1,19 @@
+
+#ifndef __MORSE_H__
+#define __MORSE_H__
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <base.h>
+
+/* TODO: make this parameterizable */
+#define DOT 1
+#define DASH 3
+#define DIVIDER 1
+#define INTERCHAR 3
+#define INTERWORD 4
+#define SCALE 100
+
+void send_morse(io_pin_t *gpio, char *message);
+
+#endif

morse_tx/main.c

@@ -0,0 +1,15 @@
+#include <avr/io.h>
+#include <util/delay.h>
+#include <base.h>
+#include <morse.h>
+
+int main(void) {
+    // io_pin_t gpio = (io_pin_t){ .ddr = &DDRB, .port = &PORTB, .addr = 7 };
+    io_pin_t gpio = (io_pin_t){ .ddr = &DDRB, .port = &PORTB, .addr = 7 };
+    set_pin_direction(&gpio, PIN_OUT);
+    while(1) {
+        send_morse(&gpio, "saluton mondo");
+        _delay_ms(2000);
+    }
+    return 0;
+}