Use the builtin RTC and display it

Its roughly %15 fast, and initializes to zero, but the display
currently shows HH:MM:SS AM/PM.

.gdbinit

@@ -0,0 +1,3 @@
+set $PWR = (PWR_TypeDef *)(0x40000000 + 0x00007000U)
+set $RCC = (RCC_TypeDef *)(0x40000000 + 0x00020000U + 0x1000U)
+set $RTC = (RTC_TypeDef *)(0x40000000 + 0x00002800U)

Makefile

@@ -70,7 +70,7 @@ DEVICE_DEFINE = $(subst XX,xx,$(shell echo $(DEVICE_FAMILY) | tr '[:lower:]' '[:
 # C pedantism
 CFLAGS =  -Wall -Wextra -Wpedantic
 # Debug/optimization
-CFLAGS += -Og -g3
+CFLAGS += -Og -ggdb
 # Architecture
 CFLAGS += -mthumb -mcpu=cortex-m0plus
 CFLAGS += -ffreestanding
@@ -99,7 +99,7 @@ build: $(OUTPUT_BIN)
 
 %.o: %.c
 	@echo "CC $@"
-	$(CC) $(CFLAGS) -c $< -o $@
+	@$(CC) $(CFLAGS) -c $< -o $@
 
 %.o: %.S
 	@echo "AS $@"

display.c

@@ -89,10 +89,25 @@ static void display_spi_init(struct display *display)
 void display_init(struct display *display, SPI_TypeDef* spi)
 {
     display->spi = spi;
+    display->is_dirty = true;
+    display->dirty_line_min = 0;
+    display->dirty_line_max = DISPLAY_HEIGHT - 1;
     display_buffer_init(&display->buffer);
     display_spi_init(display);
 }
 
+static void display_set_dirty(struct display *display, unsigned int y)
+{
+    if (!display->is_dirty) {
+        display->is_dirty = true;
+        display->dirty_line_min = y;
+        display->dirty_line_max = y;
+    } else {
+        display->dirty_line_min = MIN(y, display->dirty_line_min);
+        display->dirty_line_max = MAX(y, display->dirty_line_max);
+    }
+}
+
 void display_set_bit(struct display *display, unsigned int x, unsigned int y, uint8_t val)
 {
     if (x >= DISPLAY_WIDTH || y >= DISPLAY_HEIGHT) {
@@ -106,6 +121,8 @@ void display_set_bit(struct display *display, unsigned int x, unsigned int y, ui
     } else {
         SET_POS(*byte, x & 7);
     }
+
+    display_set_dirty(display, y);
 }
 
 void display_set_byte(struct display *display, unsigned int x, unsigned int y, uint8_t val)
@@ -120,6 +137,7 @@ void display_set_byte(struct display *display, unsigned int x, unsigned int y, u
 
     struct display_line *line = &display->buffer.lines[y];
     line->data[x >> 3] = val;
+    display_set_dirty(display, y);
 }
 
 void display_char_at(struct display *display, int *x_off, int y_off, char c, const struct font *font)
@@ -129,7 +147,8 @@ void display_char_at(struct display *display, int *x_off, int y_off, char c, con
         return;
     }
 
-    int byte_cols = 1; // TODO: Don't hardcode this
+    // TODO: Don't hardcode this
+    int byte_cols = 1;
     for (size_t x = 0; x < g->cols; x++) {
         for (size_t y = 0; y < g->rows; y++) {
             int byte_x = x >> 3;
@@ -153,10 +172,25 @@ void display_string_at(struct display *display, int x_off, int y_off, const char
 
 void display_refresh(struct display *display)
 {
-    spi_send_blocking(display->spi, (uint8_t *) &display->buffer, sizeof(display->buffer));
+    if (!display->is_dirty) {
+        return;
+    }
+
+    uint8_t *start = (uint8_t *) &display->buffer.lines[display->dirty_line_min];
+    // Data size
+    size_t size = sizeof(display->buffer.lines[0]) *
+        (display->dirty_line_max - display->dirty_line_min + 1);
+    // Trailer dummy data
+    size += 2;
+
+    spi_send_blocking(display->spi, start , size);
+    display->is_dirty = false;
 }
 
 void display_clear(struct display *display)
 {
     display_buffer_init(&display->buffer);
+    display->is_dirty = true;
+    display->dirty_line_min = 0;
+    display->dirty_line_max = DISPLAY_HEIGHT - 1;
 }

display.h

@@ -25,6 +25,7 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <assert.h>
+#include <stdbool.h>
 
 #include "spi.h"
 #include "font.h"
@@ -52,6 +53,10 @@ struct display
 {
     SPI_TypeDef *spi;
     struct display_buffer buffer;
+
+    bool is_dirty;
+    uint8_t dirty_line_min;
+    uint8_t dirty_line_max;
 };
 
 

macros.h

@@ -27,8 +27,22 @@
 
 #include <assert.h>
 
+/**
+ * I'll probably regret writing all of these at some point.
+ */
+
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
 
+#define MIN(a,b) ((a > b) ? (b) : (a))
+#define MAX(a,b) ((a < b) ? (b) : (a))
+
+/*
+ * For usage with STM32 libraries
+ */
+
+#define STM32_FIELD(x, name)                    \
+    ((x) & name##_Msk) >> (name##_Pos)
+
 /*
  * Bitwise Operations
  */

rtc.c

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "rtc.h"
+#include "stm32l0xx.h"
+#include "macros.h"
+
+static void enable_rtc_write()
+{
+    /*<! Disable write protection */
+    RTC->WPR = 0xCA;
+    RTC->WPR = 0x53;
+}
+
+static void disable_rtc_write()
+{
+    /*<! Disable write protection */
+    RTC->WPR = 0x00;
+}
+
+void rtc_init()
+{
+    uint32_t temp = RCC->CSR;
+    SET(RCC->CSR, RCC_CSR_RTCRST);
+    SET(RCC->APB1ENR, RCC_APB1ENR_PWREN);
+    SET(PWR->CR, PWR_CR_DBP);
+
+    /*<! Set RTC input clock to the LSI (low-speed internal 32.768kHz) clock */
+    SET_TO(temp, RCC_CSR_RTCSEL, RCC_CSR_RTCSEL_1);
+    SET(temp, RCC_CSR_RTCEN);
+    RCC->CSR = temp;
+
+    enable_rtc_write();
+
+    RTC->ISR = RTC_ISR_INIT;
+    while (!(RTC->ISR & RTC_ISR_INITF)) {}
+
+    /*<! Set the Clock Prescalers (32.768kHz / 128 / 256 = 1Hz */
+    /*<! Set the Async prescaler to the Maximum (divide the clock by 128) */
+    SET_TO(RTC->PRER, RTC_PRER_PREDIV_A, RTC_PRER_PREDIV_A);
+    /*<! Set the Syncronous scaler (divide the clock by 255 + 1) */
+    SET_TO(RTC->PRER, RTC_PRER_PREDIV_S, 255);
+
+    /*<! Load initial date and time */
+    // TODO
+    /* uint32_t time = 0; */
+    /* uint32_t date = 0; */
+    /*<! Set the date and time format */
+    // TODO: currently defaults to 24hr
+
+    CLR(RTC->ISR, RTC_ISR_INIT);
+
+    disable_rtc_write();
+}
+
+
+void rtc_get_time_bcd(struct time_bcd *tm_bcd)
+{
+    uint32_t time = RTC->TR;
+
+    tm_bcd->hour_tens = STM32_FIELD(time, RTC_TR_HT);
+    tm_bcd->hour_ones = STM32_FIELD(time, RTC_TR_HU);
+
+    tm_bcd->minute_tens = STM32_FIELD(time, RTC_TR_MNT);
+    tm_bcd->minute_ones = STM32_FIELD(time, RTC_TR_MNU);
+
+    tm_bcd->second_tens = STM32_FIELD(time, RTC_TR_ST);
+    tm_bcd->second_ones = STM32_FIELD(time, RTC_TR_SU);
+
+    tm_bcd->pm = STM32_FIELD(time, RTC_TR_PM);
+}

rtc.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+
+#ifndef _RTC_H_
+#define _RTC_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+struct time_bcd {
+    uint8_t hour_tens;
+    uint8_t hour_ones;
+    uint8_t minute_tens;
+    uint8_t minute_ones;
+    uint8_t second_tens;
+    uint8_t second_ones;
+    bool pm;
+};
+
+void rtc_init();
+
+void rtc_get_time_bcd(struct time_bcd *tm_bcd);
+
+#endif

system.c

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "system.h"
+
+uint32_t system_clk_freq = 0;
+
+uint32_t system_get_clk_freq()
+{
+    return system_clk_freq;
+}

system.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef _SYSTEM_H_
+#define _SYSTEM_H_
+
+#include <stdint.h>
+
+uint32_t system_get_clk_freq(void);
+
+#endif

test.c

@@ -26,15 +26,16 @@
 #include "stm32l0xx.h"
 
 #include "macros.h"
+#include "rtc.h"
 #include "spi.h"
 #include "display.h"
 #include "font-notomono-10.h"
 
 /* TODO: Start cleaning up code and adding bounds checking! */
+extern uint32_t system_clk_freq;
 
 void SystemInit()
 {
-
     /**
      * Use the MSI for the system clock, and disable all other clocks.
      */
@@ -51,6 +52,9 @@ void SystemInit()
            RCC_ICSCR_MSIRANGE,
            RCC_ICSCR_MSIRANGE_6);
 
+    /*!< Set internal representation of clock frequency to 4MHz */
+    system_clk_freq = 4u << 22;
+
     /*!< Reset
      * SW[1:0] (use MSI oscillator as system clock),
      * HPRE[3:0] (do not divide AHB clock in prescaler) ,
@@ -168,6 +172,14 @@ void init_lptim_toggler()
     CLR(GPIOA->PUPDR, GPIO_PUPDR_PUPD7);
 }
 
+static char get_char_for_digit(uint8_t bcd_digit)
+{
+    return bcd_digit + '0';
+}
+
+struct time_bcd time;
+char time_str[11] = { 0 };
+
 int main()
 {
     /** Enable Port A,B clock */
@@ -185,15 +197,34 @@ int main()
     init_lptim_toggler();
 
     display_init(&display, SPI1);
+    rtc_init();
 
     int x = 0;
     while (1) {
+
+        rtc_get_time_bcd(&time);
+
+        time_str[0] = get_char_for_digit(time.hour_tens);
+        time_str[1] = get_char_for_digit(time.hour_ones);
+        time_str[2] = ':';
+
+        time_str[3] = get_char_for_digit(time.minute_tens);
+        time_str[4] = get_char_for_digit(time.minute_ones);
+        time_str[5] = ':';
+
+        time_str[6] = get_char_for_digit(time.second_tens);
+        time_str[7] = get_char_for_digit(time.second_ones);
+        time_str[8] = time.pm ? 'P' : 'A';
+        time_str[9] = 'M';
+        time_str[10] = '\0';
+
         FLIP(GPIOB->ODR, GPIO_ODR_OD3);
         // for (int i = 0; i < 10000; i++);
         display_clear(&display);
-        display_string_at(&display, 0, font_notomono_10.height * 0, "> Option 1", &font_notomono_10);
+        display_string_at(&display, 32, font_notomono_10.height * 0, time_str, &font_notomono_10);
-        display_string_at(&display, 0, font_notomono_10.height * 1, "  Option 2", &font_notomono_10);
+        display_string_at(&display, 0, font_notomono_10.height * 2, "> Option 1", &font_notomono_10);
-        display_string_at(&display, 0, font_notomono_10.height * 2, "  Option 3", &font_notomono_10);
+        display_string_at(&display, 0, font_notomono_10.height * 3, "  Option 2", &font_notomono_10);
+        display_string_at(&display, 0, font_notomono_10.height * 4, "  Option 3", &font_notomono_10);
         display_refresh(&display);
         x++;
         if (x == DISPLAY_WIDTH) {