Hugely refactor the display

display/display.c

@@ -0,0 +1,155 @@
+#include <stdlib.h>
+#include <display.h>
+#include <util/delay.h>
+#include <base.h>
+
+/*
+struct CHAR {
+    char c;
+    uint8_t bits;
+};
+
+struct CHAR CHARSET[96] = {
+    { .c = ' ', .bits = 0x20 },
+    { .c = '!', .bits = 0x21 },
+    { .c = '"', .bits = 0x22 },
+    { .c = '#', .bits = 0x23 },
+    { .c = '$', .bits = 0x24 },
+    { .c = '%', .bits = 0x25 },
+    { .c = '&', .bits = 0x26 },
+    { .c = ''', .bits = 0x27 },
+    { .c = '(', .bits = 0x28 },
+    { .c = ')', .bits = 0x29 },
+    { .c = '*', .bits = 0x2a },
+    { .c = '+', .bits = 0x2b },
+    { .c = ',', .bits = 0x2c },
+    { .c = '-', .bits = 0x2d },
+    { .c = '.', .bits = 0x2e },
+    { .c = '/', .bits = 0x2f },
+    { .c = '0', .bits = 0x30 },
+    { .c = '1', .bits = 0x31 },
+    { .c = '2', .bits = 0x32 },
+    { .c = '3', .bits = 0x33 },
+    { .c = '4', .bits = 0x34 },
+    { .c = '5', .bits = 0x35 },
+    { .c = '6', .bits = 0x36 },
+    { .c = '7', .bits = 0x37 },
+    { .c = '8', .bits = 0x38 },
+    { .c = '9', .bits = 0x39 },
+    { .c = ':', .bits = 0x3a },
+    { .c = ';', .bits = 0x3b },
+    { .c = '<', .bits = 0x3c },
+    { .c = '=', .bits = 0x3d },
+    { .c = '>', .bits = 0x3e },
+    { .c = '?', .bits = 0x3f },
+    { .c = '@', .bits = 0x40 },
+    { .c = 'A', .bits = 0x41 },
+    { .c = 'B', .bits = 0x42 },
+    { .c = 'C', .bits = 0x43 },
+    { .c = 'D', .bits = 0x44 },
+    { .c = 'E', .bits = 0x45 },
+    { .c = 'F', .bits = 0x46 },
+    { .c = 'G', .bits = 0x47 },
+    { .c = 'H', .bits = 0x48 },
+    { .c = 'I', .bits = 0x49 },
+    { .c = 'J', .bits = 0x4a },
+    { .c = 'K', .bits = 0x4b },
+    { .c = 'L', .bits = 0x4c },
+    { .c = 'M', .bits = 0x4d },
+    { .c = 'N', .bits = 0x4e },
+    { .c = 'O', .bits = 0x4f },
+    { .c = 'P', .bits = 0x50 },
+    { .c = 'Q', .bits = 0x51 },
+    { .c = 'R', .bits = 0x52 },
+    { .c = 'S', .bits = 0x53 },
+    { .c = 'T', .bits = 0x54 },
+    { .c = 'U', .bits = 0x55 },
+    { .c = 'V', .bits = 0x56 },
+    { .c = 'W', .bits = 0x57 },
+    { .c = 'X', .bits = 0x58 },
+    { .c = 'Y', .bits = 0x59 },
+    { .c = 'Z', .bits = 0x5a },
+    { .c = '[', .bits = 0x5b },
+    { .c = ' ', .bits = 0x5c },
+    { .c = ']', .bits = 0x5d },
+    { .c = '^', .bits = 0x5e },
+    { .c = '_', .bits = 0x5f },
+    { .c = '`', .bits = 0x60 },
+    { .c = 'a', .bits = 0x61 },
+    { .c = 'b', .bits = 0x62 },
+    { .c = 'c', .bits = 0x63 },
+    { .c = 'd', .bits = 0x64 },
+    { .c = 'e', .bits = 0x65 },
+    { .c = 'f', .bits = 0x66 },
+    { .c = 'g', .bits = 0x67 },
+    { .c = 'h', .bits = 0x68 },
+    { .c = 'i', .bits = 0x69 },
+    { .c = 'j', .bits = 0x6a },
+    { .c = 'k', .bits = 0x6b },
+    { .c = 'l', .bits = 0x6c },
+    { .c = 'm', .bits = 0x6d },
+    { .c = 'n', .bits = 0x6e },
+    { .c = 'o', .bits = 0x6f },
+    { .c = 'p', .bits = 0 },
+    { .c = 'q', .bits = 0 },
+    { .c = 'r', .bits = 0 },
+    { .c = 's', .bits = 0 },
+    { .c = 't', .bits = 0 },
+    { .c = 'u', .bits = 0 },
+    { .c = 'v', .bits = 0 },
+    { .c = 'w', .bits = 0 },
+    { .c = 'x', .bits = 0 },
+    { .c = 'y', .bits = 0 },
+    { .c = 'z', .bits = 0 },
+    { .c = ' ', .bits = 0 },
+    { .c = ' ', .bits = 0 },
+    { .c = ' ', .bits = 0 },
+    { .c = ' ', .bits = 0 },
+    { .c = ' ', .bits = 0 },
+};
+*/
+
+void display_strobe_line(gpio_t *line) {
+    set_line(line);
+    _delay_us(100);
+    clear_line(line);
+    _delay_us(100);
+}
+
+void write_instruction(display_t *disp, uint8_t bitcode) {
+    clear_line(&disp->register_select);
+    sr_send_msb(&disp->reg, bitcode);
+    _delay_ms(1);
+    display_strobe_line(&disp->enable);
+}
+
+void write_char(display_t *disp, uint8_t bitcode) {
+    set_line(&disp->register_select);
+    sr_send_msb(&disp->reg, bitcode);
+    _delay_ms(1);
+    display_strobe_line(&disp->enable);
+}
+
+void display_init(display_t *disp) {
+    sr_initialize(&disp->reg);
+    set_line_direction(&disp->register_select, LINE_OUT);
+    set_line_direction(&disp->enable, LINE_OUT);
+    write_instruction(disp, 0b00111100);
+}
+
+void display_clear(display_t *disp) {
+    write_instruction(disp, 0x01);
+    write_instruction(disp, 0x02);
+}
+
+void display_enable(display_t *disp) {
+    write_instruction(disp, 0x0e);
+}
+
+void display_write_message(display_t *disp, const char *msg) {
+    for (size_t i = 0; msg[i] != 0; i++) {
+        write_char(disp, msg[i]);
+    }
+}
+
+

display/display.h

@@ -0,0 +1,50 @@
+/* This library covers a five-wire diagnostic display board.
+ *
+ * Hardware:
+ * 74HC595 shift register
+ * Adafruit HD44780 LCD
+ *
+ * Input pins:
+ *  SDI -- Serial data in. This leads to the 74HC595, pin 14 (A).
+ *  CLK -- Clock pulse. One bit will be shifted into the device on each rising
+ *    edge. This leads to the 74HC595, pin 11 (Shift Clock).
+ *  LS -- Latch pulse. All data in the shift register will be sent to the
+ *    output on a rising edge. This leads to the 74HC595, pin 12 (Latch Clock);
+ *  RS -- Register select. 0 to write an instruction to the display, 1 to write
+ *    data to the display.
+ *  E -- Enable. This tells the display to read the data. The display will get
+ *    the data on the shift register outputs, so be sure to send LS before
+ *    sending E.
+ *
+ * 74HC595 -> HD44780
+ *  Qa -> D0
+ *  Qb -> D1
+ *  Qc -> D2
+ *  Qd -> D3
+ *  Qe -> D4
+ *  Qf -> D5
+ *  Qg -> D6
+ *  Qh -> D7
+ */
+
+#ifndef __DISPLAY_H__
+#define __DISPLAY_H__
+
+#include <shift_register.h>
+
+typedef struct DISPLAY {
+    shift_register_t reg;
+    gpio_t register_select;
+    gpio_t enable;
+} display_t;
+
+void display_init(display_t *);
+
+void display_clear(display_t *);
+
+void display_enable(display_t *);
+
+void display_write_message(display_t *, const char *);
+
+#endif
+

flake.nix

@@ -106,7 +106,7 @@
           name = "lcd";
           src = ./.;
 
-          includes = [ "base" "shift_register" "spi" ];
+          includes = [ "base" "display" "shift_register" "spi" ];
 
           MCU = "atmega32u4";
           CHIP_SELECT = "AVR_ATmega32u4";
@@ -117,9 +117,10 @@
           buildPhase = ''
             ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o base.o -c ${src}/base/base.c
             ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o spi.o -c ${src}/spi/spi.c
-            ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o reg.o -c ${src}/shift_register/reg.c
+            ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o reg.o -c ${src}/shift_register/shift_register.c
+            ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o display.o -c ${src}/display/display.c
             ${avr.gcc}/bin/avr-gcc ${CFLAGS} ${INCLUDE_DIRS} -o main.o -c ${src}/lcd/main.c
-            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -o main.elf main.o reg.o spi.o base.o
+            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -o main.elf main.o display.o reg.o spi.o base.o
             $OBJCOPY -O ihex main.elf main.hex
             '';
           installPhase = ''

lcd/main.c

@@ -2,76 +2,11 @@
 #include <util/delay.h>
 #include <base.h>
 #include <spi.h>
-#include <reg.h>
-
-typedef struct HD44780 {
-    shift_register_t reg;
-    gpio_t register_select;
-    gpio_t enable;
-} hd44780_t;
-
-void strobe_line(gpio_t *line) {
-    set_line(line);
-    _delay_ms(1);
-    clear_line(line);
-    _delay_ms(1);
-}
-
-void hd44780_init(hd44780_t *disp) {
-    spi_initialize(disp);
-    set_line_direction(&disp->register_select, LINE_OUT);
-    set_line_direction(&disp->enable, LINE_OUT);
-    send_msb(&disp->reg, 0b00111100);
-}
-
-void hd44780_clear(hd44780_t *disp) {
-    clear_line(&disp->register_select);
-    send_msb(&disp->reg, 0b00000001);
-    _delay_ms(1);
-    strobe_line(&disp->enable);
-
-    send_msb(&disp->reg, 0b00000010);
-    _delay_ms(1);
-    strobe_line(&disp->enable);
-}
-
-void hd44780_display(hd44780_t *disp) {
-    clear_line(&disp->register_select);
-    send_msb(&disp->reg, 0b00001110);
-    _delay_ms(1);
-    strobe_line(&disp->enable);
-}
-
-void hd44780_write_char(hd44780_t *disp, uint8_t bitcode) {
-    set_line(&disp->register_select);
-    send_msb(&disp->reg, bitcode);
-    strobe_line(&disp->enable);
-}
-
-void hd44780_write(hd44780_t *disp) {
-    set_line(&disp->register_select);
-
-    hd44780_write_char(disp, 0b01001000);
-    hd44780_write_char(disp, 0b01000101);
-    hd44780_write_char(disp, 0b01001100);
-    hd44780_write_char(disp, 0b01001100);
-    hd44780_write_char(disp, 0b01001111);
-    hd44780_write_char(disp, 0b00101100);
-
-    hd44780_write_char(disp, 0b00100000);
-
-    hd44780_write_char(disp, 0b01001101);
-    hd44780_write_char(disp, 0b01011001);
-
-    hd44780_write_char(disp, 0b00100000);
-
-    hd44780_write_char(disp, 0b01000010);
-    hd44780_write_char(disp, 0b01000001);
-    hd44780_write_char(disp, 0b01010100);
-}
+#include <shift_register.h>
+#include <display.h>
 
 int main(void) {
-    hd44780_t display = {
+    display_t display = {
         .reg = {
             .output         = { .ddr = &DDRB, .port = &PORTB, .pin = &PINB, .addr = 5 },
             .latch_clock    = { .ddr = &DDRB, .port = &PORTB, .pin = &PINB, .addr = 6 },
@@ -85,13 +20,14 @@ int main(void) {
     set_line_direction(&light, LINE_OUT);
     clear_line(&light);
 
-    hd44780_init(&display);
+    display_init(&display);
 
-    hd44780_clear(&display);
+    display_clear(&display);
     _delay_ms(500);
 
-    hd44780_write(&display);
-    hd44780_display(&display);
+    const char msg[] = "Hello, my bat";
+    display_write_message(&display, msg);
+    display_enable(&display);
 
     set_line(&light);