implement rtc

src/ds_rtc.c

@@ -0,0 +1,67 @@
+/**
+ * TODO file description
+ */
+
+#include <pico/stdlib.h>
+#include <stdint.h>
+#include <hardware/i2c.h>
+#include <string.h>
+
+#include "ds_rtc.h"
+#include "pinout.h"
+
+#define I2C_ADDR_RTC    0b1101000
+#define TIMEOUT_US 10000
+
+#define TRY(what) do { \
+    rv = (what);       \
+    if (rv < 0) { return rv; } \
+} while (0)
+
+
+static int rtc_read(uint8_t start, uint8_t *dest, size_t len) {
+    int rv;
+    TRY(i2c_write_timeout_us(i2c0, I2C_ADDR_RTC, &start, 1, true, TIMEOUT_US));
+    TRY(i2c_read_timeout_us(i2c0, I2C_ADDR_RTC, dest, len, false, TIMEOUT_US));
+    return 0;
+}
+
+static int rtc_write(uint8_t start, const uint8_t *data, size_t len) {
+    int rv;
+    if (len > 19) return -1;
+    uint8_t scratch[20];
+    scratch[0] = start;
+    memcpy(&scratch[1], data, len);
+    TRY(i2c_write_timeout_us(i2c0, I2C_ADDR_RTC, scratch, len + 1, true, TIMEOUT_US));
+    return 0;
+}
+
+int rtc_get_time(struct rtc_time *dest) {
+    int rv;
+    uint8_t buf[3];
+    TRY(rtc_read(0x00, buf, 3));
+
+    dest->second = (buf[0] & 15) + (buf[0] >> 4) * 10;
+    dest->minute = (buf[1] & 15) + (buf[1] >> 4) * 10;
+
+    if (buf[2] & 0x40) {
+        // 12h time?
+        dest->hour = (buf[2] & 15) + ((buf[2] & 0x20) != 0) * 12 + ((buf[2] & 0x10) != 0) * 10;
+    } else {
+        dest->hour = (buf[2] & 15) + ((buf[2] >> 4) & 3) * 10;
+    }
+
+    return 0;
+}
+
+int rtc_set_time(const struct rtc_time *time) {
+    int rv;
+    uint8_t buf[3];
+
+    buf[0] = (time->second % 10) + ((time->second / 10) << 4);
+    buf[1] = (time->minute % 10) + ((time->minute / 10) << 4);
+    buf[2] = (time->hour % 10) + ((time->hour / 10) << 4);
+
+    TRY(rtc_write(0x00, buf, 3));
+    return 0;
+}

src/ds_rtc.h

@@ -0,0 +1,18 @@
+/**
+ * TODO file description
+ */
+
+#ifndef ZAVLAHA_DS_RTC_H
+#define ZAVLAHA_DS_RTC_H
+
+
+struct rtc_time {
+  uint8_t hour;
+  uint8_t minute;
+  uint8_t second;
+};
+
+int rtc_get_time(struct rtc_time *dest);
+int rtc_set_time(const struct rtc_time *time);
+
+#endif //ZAVLAHA_DS_RTC_H

src/main.c

@@ -6,6 +6,7 @@
 #include <hardware/irq.h>
 #include "pinout.h"
 #include "lcd.h"
+#include "ds_rtc.h"
 
 /*
 
@@ -132,12 +133,24 @@ int main()
     lcd_init();
     lcd_puts("HELLO WORLD!");
 
+
     uint cnt = 0;
     char buf[16];
     while (1) {
         lcd_clear();
         lcd_puts("HELLO WORLD!");
 
+        // Try to read RTC
+        struct rtc_time time;
+        if (0 == rtc_get_time(&time)) {
+            sprintf(buf, "%02d:%02d:%02d", time.hour, time.minute, time.second);
+            lcd_xy(0, 2);
+            lcd_puts(buf);
+        } else {
+            lcd_xy(0, 2);
+            lcd_puts("RTC err!");
+        }
+
         gpio_put(PIN_LED, 1); // LED on
 
         uint16_t moisture = moisture_read();

src/pinout.h

@@ -24,6 +24,5 @@
 
 // must be shifted left before adding the RW bit!
 #define I2C_ADDR_EEPROM 0b1010000
-#define I2C_ADDR_RTC    0b1101000
 
 #endif //ZAVLAHA_PINOUT_H