Support for reading temperature/humidity from DHT11 and DHT22, bump v1.4

.gitignore

@@ -7,6 +7,7 @@ software/adc
 software/blink
 software/blink_ws2812
 software/button
+software/dht11
 software/debugConsole
 software/fade_ws2812
 software/hardwarePWM
@@ -19,3 +20,6 @@ software/rgb_cycle_ws2812
 software/servo
 software/softPWM
 software/spi_LTC1448
+
+firmware/main.hex
+firmware/main.elf

Readme.md

@@ -2,7 +2,7 @@
 
 For more details: <http://littlewire.cc>
 
-Current version is: **v1.3**
+Current version is: **v1.4**
 
 Previous version releases can be found at: <https://github.com/littlewire/Little-Wire/releases>
 

firmware/main.c

@@ -64,7 +64,7 @@
 #define delayMicroseconds(value) _delay_us(value);
 #define sbi(register,bit) (register|=(1<<bit))
 #define cbi(register,bit) (register&=~(1<<bit))
-const uint8_t LITTLE_WIRE_VERSION = 0x13;	
+const uint8_t LITTLE_WIRE_VERSION = 0x14;	
 enum
 {
 	// Generic requests
@@ -827,6 +827,13 @@ uchar	usbFunctionSetup(uchar data[8])
 
 		return 0;		
 	}
+	if( req == 56) /* dht read */
+	{
+		rxBuffer[0]=data[2];
+		jobState=18;
+		return 0;
+	}
+
 #if 0 
 	if ((req & 0xF0) == 0xD0) /* pic24f send bytes */
 	{
@@ -1063,6 +1070,113 @@ unsigned char I2C_Read( unsigned char ack )
 
 	return res;
 }
+
+#define DHT11 0
+#define DHT22 1
+
+#define DHT_TIMEOUT 255
+#define DHT_DELAY 10
+#define DHT_LEN 4
+
+#define DHT_SUCCESS 0
+#define DHT_TIMEOUT_ERR 128
+#define DHT_CHECKSUM_ERR 255
+
+uint8_t DHT_Read(unsigned char type) {
+    uint8_t timeout = 0;
+    uint8_t len = 0;
+    uint8_t bit_index = 7;
+    uint8_t byte_index = 0;
+
+    uint16_t f;
+
+    pinMode(B,DATA_PIN,OUTPUT);
+
+    sendBuffer[0] = 0; sendBuffer[1] = 0; sendBuffer[2] = 0; sendBuffer[3] = 0; sendBuffer[4] = 0;
+
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+      digitalWrite(B,DATA_PIN, LOW);
+      _delay_ms(18);
+      digitalWrite(B,DATA_PIN, HIGH);
+      _delay_us(40);
+
+      pinMode(B, DATA_PIN, INPUT);
+      internalPullup(B, DATA_PIN, DISABLE);
+
+      timeout = DHT_TIMEOUT;
+      while(!digitalRead(B, DATA_PIN)) { // Wait for 1
+        if (timeout-- == 0) {
+          return DHT_TIMEOUT_ERR;
+        }
+      }
+
+      timeout = DHT_TIMEOUT;
+      while(digitalRead(B, DATA_PIN)) { // Wait for 0
+          _delay_us(1);
+        if (timeout-- == 0) {
+          return DHT_TIMEOUT_ERR;
+        }
+      }
+
+
+      for (uint8_t i = 0; i < 40; i++) {
+        timeout = DHT_TIMEOUT;
+        while(!digitalRead(B, DATA_PIN)) { // Wait for 1
+          if (timeout-- == 0) {
+            return DHT_TIMEOUT_ERR;
+          }
+        }
+
+        len = 0;
+        timeout = DHT_TIMEOUT;
+        while(digitalRead(B, DATA_PIN)) { // Wait for 0
+          _delay_us(DHT_DELAY);
+          if (len++ == DHT_TIMEOUT) {
+            return DHT_TIMEOUT_ERR;
+          }
+        }
+
+        if (len >= DHT_LEN) {
+          sendBuffer[byte_index] |= (1 << bit_index);
+        }
+
+        if (bit_index == 0) {
+          bit_index = 7;
+          byte_index++;
+        } else {
+          bit_index--;
+        }
+
+      }
+    }
+
+    uint16_t checksum = sendBuffer[0] + sendBuffer[1] + sendBuffer[2] + sendBuffer[3];
+    if (sendBuffer[4] != (checksum & 0x00FF)) {
+      return DHT_CHECKSUM_ERR;
+    }
+
+    if (type == DHT11) {
+      // Expand DHT11 values to DHT22 format
+      f = sendBuffer[0];
+      f *= 10;
+      sendBuffer[0] = 0x00FF & f;
+      sendBuffer[1] = 0x00FF & (f >> 8);
+
+      f = sendBuffer[2];
+      f *= 10;
+      sendBuffer[2] = 0x00FF & f;
+      sendBuffer[3] = 0x00FF & (f >> 8);
+    } else if (type == DHT22) {
+      f = sendBuffer[1];
+      sendBuffer[1] = sendBuffer[0];
+      sendBuffer[0] = f;
+
+      f = sendBuffer[3];
+      sendBuffer[3] = sendBuffer[2];
+      sendBuffer[2] = f;
+    }
+    return 0;
+}
 // ----------------------------------------------------------------------------
 
 
@@ -1382,7 +1496,13 @@ int main(void) {
 				}				
 				jobState=0;
 			break;
-
+      case 18: /* dht11/dht22 read */				
+        sendBuffer[4] = DHT_Read(rxBuffer[0]); // error msg
+        sendBuffer[8] = 5;
+
+				jobState=0;
+			break;
+
 			default:
 				jobState=0;
 			break;

software/Makefile

@@ -28,6 +28,7 @@ CFLAGS  = $(USBFLAGS) $(LIBS) -I$(INCLUDE) -O -g $(OSFLAG)
 LWLIBS = littleWire littleWire_util littleWire_servo opendevice
 EXAMPLES  = adc blink blink_ws2812 rgb_cycle_ws2812 fade_ws2812 button servo i2c_blinkM
 EXAMPLES += spi_LTC1448 onewire softPWM hardwarePWM debugConsole lwbuttond i2c_nunchuck
+EXAMPLES += dht11
 
 .PHONY:	clean library docs
 

software/examples/dht11.c

@@ -0,0 +1,56 @@
+/*
+	Updated for the new firmware: July 2012
+	by ihsan Kehribar <[email protected]>
+
+	Created: December 2011
+	by ihsan Kehribar <[email protected]>
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include "littleWire.h"
+#include "littleWire_util.h"
+
+unsigned char version;
+
+dht_reading val;
+
+int main(int argc, char **argv)
+{
+	littleWire *lw = NULL;
+
+	lw = littleWire_connect();
+
+	if(lw == NULL){
+		printf("> Little Wire could not be found!\n");
+		exit(EXIT_FAILURE);
+	}
+
+	version = readFirmwareVersion(lw);
+	printf("> Little Wire firmware version: %d.%d\n",((version & 0xF0)>>4),(version&0x0F));	
+	if(version<0x14)
+	{
+		printf("> This example requires the new 1.4 version firmware. Please update soon.\n");
+		return 0;
+	}
+
+	while(1)
+	{
+    val = dht_read(lw, DHT11);
+    if (!val.error) {
+    printf("humidity: %f, temp %f\n", (float)val.humid/10.0, (float)val.temp/10.0);
+    } else {
+      printf("Error Reading sensor!");
+    }
+
+		if(lwStatus<0)
+		{
+			printf("> lwStatus: %d\n",lwStatus);
+			printf("> Connection error!\n");
+			return 0;
+		}
+
+		delay(5000);
+	}
+}

software/library/littleWire.c

@@ -389,7 +389,19 @@ void ws2812_preload(littleWire* lwHandle, unsigned char r,unsigned char g,unsign
 {
 	lwStatus=usb_control_msg(lwHandle, 0xC0, 54, (g<<8) | 0x20, (b<<8) | r, rxBuffer, 8, USB_TIMEOUT);
 }
+
+dht_reading dht_read(littleWire* lwHandle, unsigned char type)
+{
+  lwStatus=usb_control_msg(lwHandle, 0xC0, 56, type, 0, rxBuffer, 8, USB_TIMEOUT);
 
+	delay(100);
+
+  lwStatus=usb_control_msg(lwHandle, 0xC0, 40, 0, 0, rxBuffer, 8, USB_TIMEOUT);
+
+  return *(dht_reading*) (void*) rxBuffer;
+}
+
+
 int customMessage(littleWire* lwHandle,unsigned char* receiveBuffer,unsigned char command,unsigned char d1,unsigned char d2, unsigned char d3, unsigned char d4)
 {
 	int i;

software/library/littleWire.h

@@ -36,6 +36,7 @@
 #include "opendevice.h"			// common code moved to separate module
 #include "littleWire_util.h"
 #include <stdio.h>
+#include <stdint.h>
 
 #define	VENDOR_ID 0x1781
 #define	PRODUCT_ID 0x0c9f
@@ -93,6 +94,15 @@
 #define MOSI_PIN PIN4
 #define RESET_PIN PIN3
 
+#define DHT11 0
+#define DHT22 1
+
+typedef struct dht_reading {
+  uint16_t humid;
+  uint16_t temp;
+  uint8_t error;
+} dht_reading;
+
 extern unsigned char rxBuffer[RX_BUFFER_SIZE]; /* This has to be unsigned for the data's sake */
 extern unsigned char ROM_NO[8];
 extern int lwStatus;
@@ -557,6 +567,7 @@ void ws2812_preload(littleWire* lwHandle, unsigned char r,unsigned char g,unsign
 
   /*! @} */
 
+dht_reading dht_read(littleWire* lwHandle, unsigned char type);
 
 /**
 * @mainpage Introduction