2 files changed, 183 insertions(+), 0 deletions(-)

A arm03/include/display.h
A arm03/src/display.c

@@ 0,0 1,44 @@
+#include <stdint.h>
+#include "pin.h"
+
+#ifndef DISPLAY_H
+#define DISPLAY_H
+
+typedef struct {
+  // Display board configuration
+  uint16_t digits_count;
+  pin_t pin_data;
+  pin_t pin_sftclk;
+  pin_t pin_strobe;
+
+  // Current application data
+  uint32_t bcd_digits;
+  uint8_t digit_dots;
+
+  // Current application state
+  uint8_t digits_en;
+
+  // Current internal state of the display
+  uint16_t current_cycle;
+  uint32_t current_shifter;
+  uint8_t current_digit;
+  uint16_t max_value;
+} display_t;
+
+typedef enum {
+  DISPLAY_UPDATE_NEW_DIGIT,
+  DISPLAY_UPDATE_DISPLAY_DIGIT,
+  DISPLAY_UPDATE_SHIFT,
+} display_update_state_t;
+
+void display_init(display_t* display, uint16_t digits, pin_t pin_data, pin_t pin_sftclk, pin_t pin_strobe);
+
+void display_convert_number(display_t* display, uint32_t number);
+void display_digit_set(display_t* display, uint8_t digit, uint8_t number);
+
+void display_dots(display_t* display, uint8_t dots);
+void display_enable_digit(display_t* display, uint8_t digit, uint8_t enable);
+
+display_update_state_t display_update(display_t* display);
+
+#endif // DISPLAY_H

@@ 0,0 1,139 @@
+#include "display.h"
+#include "registers.h"
+
+#define CYCLES 17
+
+const char numbers_seven_segments[11] = {
+  0x3F, /* 0 */
+  0x06, /* 1 */
+  0x5B, /* 2 */
+  0x4F, /* 3 */
+  0x66, /* 4 */
+  0x6D, /* 5 */
+  0x7D, /* 6 */
+  0x07, /* 7 */
+  0x7F, /* 8 */
+  0x6F, /* 9 */
+  0x40, /* - */
+};
+
+uint16_t pow16(uint16_t num, uint8_t pow) {
+  for (uint16_t i = 0; i < pow; i++) {
+    num *= num;
+  }
+  return num;
+}
+
+
+void display_init(display_t *display, uint16_t digits, pin_t pin_data,
+                  pin_t pin_sftclk, pin_t pin_strobe) {
+  display->digits_count = digits;
+  display->bcd_digits = 0;
+
+  display->digits_en = ~0;
+  display->digit_dots = ~0;
+
+  display->pin_data = pin_data;
+  display->pin_sftclk = pin_sftclk;
+  display->pin_strobe = pin_strobe;
+
+  display->max_value = pow16(10, digits);
+  display->current_cycle = 0;
+  display->current_shifter = 0;
+  display->current_digit = 0;
+}
+
+/**
+ * @brief Convert a digit from a regular number to seven segments
+ * @param[in] number The number to convert
+ * @param[in] digit The digit from least significant, starting with 0
+ * @return Description
+ */
+uint16_t seven_segment_convert(uint16_t number, uint16_t digit, uint8_t dot);
+
+/**
+ * @brief Converts a number to serial strem to send via the SIPO register.
+ * @param[in] number The bcd number to convert to the values for shift register
+ * @param[in] digit The digit from the least significant, starting with 0
+ * @return Description
+ */
+uint16_t convert_num_digit(uint16_t bcd_number, uint8_t digits_count, uint8_t digit, uint8_t dot);
+
+uint16_t seven_segment_convert(uint16_t bcd_number, uint16_t digit, uint8_t dot) {
+  return ~(numbers_seven_segments[(bcd_number >> (digit << 2)) & 0xF] | dot << 7);
+}
+
+uint16_t convert_num_digit(uint16_t number, uint8_t digits_count, uint8_t digit, uint8_t dot) {
+  uint16_t seven_segments = seven_segment_convert(number, digits_count - 1 - digit, dot);
+  uint16_t digits = 1 << digit;
+
+  return (seven_segments << 8) | digits;
+}
+
+void display_dots(display_t* display, uint8_t dots) {
+  display->digit_dots = dots;
+}
+
+void display_convert_number(display_t *display, uint32_t number) {
+  uint32_t bcd = 0;
+  for (uint8_t i = 0; i < display->digits_count; i++) {
+    bcd |= (number % 10) << (i << 2);
+    number /= 10;
+  }
+  display->bcd_digits = bcd;
+}
+
+void display_enable_digit(display_t *display, uint8_t digit, uint8_t enable) {
+  uint16_t digits = 1 << digit;
+  if (enable != 0) {
+    display->digits_en |= digits;
+  } else {
+    display->digits_en &= ~digits;
+  }
+}
+
+void display_digit_set(display_t *display, uint8_t digit, uint8_t number) {
+  reg_write_bits_pos(&display->bcd_digits, number, digit << 2, 0xF);
+}
+
+display_update_state_t display_update(display_t *display) {
+  display_update_state_t state = DISPLAY_UPDATE_SHIFT;
+
+  if (display->current_cycle == 0) {
+    // Set up.
+    display->current_digit = (display->current_digit + 1) % display->digits_count;
+
+    if (display->digits_en & (1 << display->current_digit)) {
+      display->current_shifter = convert_num_digit(
+          display->bcd_digits, display->digits_count, display->current_digit,
+          (display->digit_dots >> display->current_digit) & 1);
+    } else {
+      // Still send the data even for disabled digits,
+      // to prevent display having different brightness
+      // depending on how many digits are currently on.
+      display->current_shifter = 0;
+    }
+
+    state = DISPLAY_UPDATE_NEW_DIGIT;
+  }
+
+  if (display->current_cycle < CYCLES - 1) {
+    pin_write(&display->pin_data,
+              reg_read_bits_pos(&display->current_shifter,
+                                15 - display->current_cycle,
+                                1));
+
+    pin_set(&display->pin_sftclk);
+    pin_reset(&display->pin_sftclk);
+  } else {
+    // Send strobe
+    pin_set(&display->pin_strobe);
+    pin_reset(&display->pin_strobe);
+
+    state = DISPLAY_UPDATE_DISPLAY_DIGIT;
+  }
+
+  display->current_cycle = (display->current_cycle + 1) % CYCLES;
+
+  return state;
+}