added 18B20 and iButton support

main.c

@@ -55,53 +55,99 @@ void main()
 	char charbuf[21];
 
 	int dots = 0;
+	bool signal = false, last_signal;
 	while (1) {
-        bool signal = ow_reset(OW_PIN);
+        last_signal = signal;
+        signal = ow_reset(OW_PIN);
         if (!signal) {
+            if (last_signal) {
                 lcd_clear();
-            lcd_puts("No 1-Wire detected...");
+            }
+            lcd_puts_xy(0,0,"No 1-Wire detected..");
             dots = 0;
         } else {
+            if (!last_signal) {
+                lcd_clear();
+            }
+
             ow_write(OW_PIN, 0x33);
             ow_read_arr(OW_PIN, addr, 8);
 
-            lcd_clear();
+            // Show chip type
+            switch (addr[0]) {
+                case 0x10:
+                    sprintf(charbuf, "18S20  ");
+                    break;
 
+                case 0x28:
+                    sprintf(charbuf, "18B20  ");
+                    break;
+
+                case 0x01:
+                    sprintf(charbuf, "iButton");
+                    break;
+
+                default:
+                    sprintf(charbuf, "UNKNOWN");
+                    break;
+            }
+            lcd_puts_xy(12, 0, charbuf);
+
+            // Show address
             char *p = charbuf;
             for(uint8_t i = 0; i < 4; i++) {
                 p += sprintf(p, "%02X", addr[i]);
                 if (i < 3) *p++ = ':';
             }
-            lcd_puts(charbuf);
-            lcd_xy(0, 1);
+            lcd_puts_xy(0, 0, charbuf);
+
 
             p = charbuf;
             for(uint8_t i = 0; i < 4; i++) {
                 p += sprintf(p, "%02X", addr[4+i]);
                 if (i < 3) *p++ = ':';
             }
-            lcd_puts(charbuf);
-
-            ds1820_single_measure(OW_PIN);
-            uint16_t cels = ds1820_read_temp_c(OW_PIN);
+            lcd_puts_xy(0, 1, charbuf);
+
+            // Measure temperature
+            int16_t cels;
+            if (addr[0] == 0x10 || addr[0] == 0x28) {
+                ds18x20_single_measure(OW_PIN);
+                if (addr[0] == 0x10) {
+                    // 18S20
+                    cels = ds18s20_read_temp_c(OW_PIN);
+                } else {
+                    // 18B20
+                    cels = ds18b20_read_temp_c(OW_PIN);
+                }
 
-            if (cels == 850) {
-                lcd_xy(12, 0);
+                if (cels == TEMP_ERROR || cels == 850) {
+                    lcd_xy(12, 1);
                     for (uint8_t i = 0; i <= dots; i++) {
                         lcd_putc('.');
                     }
                     dots = (dots + 1) % 3;
-            } else {
+                }
+                else {
                     p = charbuf;
+
+                    if (cels < 0) {
+                        *p++ = '-';
+                        cels = -cels;
+                    }
+
                     p += sprintf(p, "%d", cels / 10);
                     *p++ = '.';
                     p += sprintf(p, "%d", cels % 10);
-                *p++ = 0xDF;
+                    *p++ = 0xDF; // ring symbol
                     *p++ = 'C';
-                *p++ = 0;
+                    *p++ = ' '; // padding to prevent artifacts if the number shrinks (we're not clearing screen when 1w is connected)
+                    *p++ = ' ';
+                    *p++ = ' ';
+                    *p = 0;
 
-                lcd_xy(12, 0);
-                lcd_puts(charbuf);
+                    lcd_puts_xy(12, 1, charbuf);
+                }
             }
         }
 

onewire.c

@@ -189,9 +189,8 @@ uint8_t crc8(uint8_t *addr, uint8_t len)
 
 // --- utils for DS1820 ---
 
-
-/** Read temperature in 0.0625°C, or TEMP_ERROR on error */
-int16_t ds1820_read_temp(uint8_t pin)
+/** Read temperature in 0.0625°C */
+int16_t ds18s20_read_temp(uint8_t pin)
 {
 	ow_write(pin, READ_SCRATCHPAD);
 	uint8_t bytes[9];
@@ -213,24 +212,54 @@ int16_t ds1820_read_temp(uint8_t pin)
 	}
 }
 
+int16_t conv0_0625to0_1(int32_t temp) {
+	temp *= 625;
+	uint16_t rem = temp % 1000;
+	temp /= 1000;
+	if (rem >= 500) temp++;
+	return (int16_t) temp;
+}
+
 /** Read temperature in 0.1°C, or TEMP_ERROR on error */
-int16_t ds1820_read_temp_c(uint8_t pin)
+int16_t ds18s20_read_temp_c(uint8_t pin)
+{
+	int16_t value = ds18s20_read_temp(pin);
+	if (value == TEMP_ERROR) return TEMP_ERROR;
+	return conv0_0625to0_1(value);
+}
+
+/** Read temperature in 0.0625°C */
+uint16_t ds18b20_read_temp(uint8_t pin)
 {
-	int32_t temp = ds1820_read_temp(pin);
+	ow_write(pin, READ_SCRATCHPAD);
+	uint8_t bytes[9];
+	ow_read_arr(pin, bytes, 9);
 
-	if (temp == TEMP_ERROR)
+	uint8_t crc = crc8(bytes, 8);
+	if (crc != bytes[8]) {
 		return TEMP_ERROR;
+	}
 
-	temp *= 625;
-	uint16_t rem = temp % 1000;
-	temp /= 1000;
-	if (rem >= 500) temp++;
+	int32_t value = bytes[0] | ((bytes[1] & 0x7) << 8); // value in 0.0625
+	if (bytes[1] & 0x80) {
+		value = -value;
+	}
+	if (value == 0x0550) {
+		return TEMP_ERROR;
+	}
 
-	return (int16_t) temp;
+	return value;
 }
 
+/** Read temperature in 0.1°C, or TEMP_ERROR on error */
+int16_t ds18b20_read_temp_c(uint8_t pin)
+{
+	int16_t value = ds18b20_read_temp(pin);
+	if (value == TEMP_ERROR) return TEMP_ERROR;
+	return conv0_0625to0_1(value);
+}
 
-bool ds1820_single_measure(uint8_t pin)
+bool ds18x20_single_measure(uint8_t pin)
 {
 	ow_reset(pin);
 	ow_write(pin, SKIP_ROM);

onewire.h

@@ -40,14 +40,15 @@ uint8_t crc8(uint8_t *addr, uint8_t len);
  * Read temperature in 0.0625°C, or TEMP_ERROR on error
  * Use this where you'd normally use READ_SCRATCHPAD
  */
-int16_t ds1820_read_temp(uint8_t pin);
-
+int16_t ds18s20_read_temp(uint8_t pin);
 
 /**
  * Read temperature in 0.1°C, or TEMP_ERROR on error
  * Use this where you'd normally use READ_SCRATCHPAD
  */
-int16_t ds1820_read_temp_c(uint8_t pin);
+int16_t ds18s20_read_temp_c(uint8_t pin);
+
+int16_t ds18b20_read_temp_c(uint8_t pin);
 
 /**
  * Perform a temperature measurement with single DS1820 device on the line
@@ -55,4 +56,4 @@ int16_t ds1820_read_temp_c(uint8_t pin);
  *
  * Returns false on failure (device not connected)
  */
-bool ds1820_single_measure(uint8_t pin);
+bool ds18x20_single_measure(uint8_t pin);