flotulopex
- 31st December 2019, 17:14
Hello,
Here is my code to read temperature and humidity from a DHT11 sensor. It has also the SLEEP functionality.
I tried to make it as simple and clear as possible :)
' ====== PIC 16F690 FUSES ================================================== ========================
' External oscillator 8MHz
@ __config _FCMEN_OFF &_IESO_OFF &_CPD_OFF &_WDT_OFF &_HS_OSC &_BOR_OFF &_CP_OFF &_PWRTE_OFF &_MCLRE_OFF
' ====== REGISTERS ================================================== ===============================
' Registers 76543210
OPTION_REG = %10000000 ' PORT A&B Pull-Ups and Prescaler (def.: %11111111)
OSCCON = %00000000 ' External (def.: %01101000)
WDTCON = %00001001 ' Enable WatchDog (the REGISTER, not the fuse) for SLEEP
' ====== DEFINES ================================================== =================================
DEFINE OSC 8 ' don't forget the external oscillator
' ====== VARIABLES ================================================== ===============================
DHT_Data VAR BYTE [32] ' hold bitwise humidity and temperature data
HUMIDITY VAR BYTE ' holds humidity value
TEMPERATURE VAR BYTE ' holds temperature value
x VAR BYTE ' a counter
SerialData VAR PORTA.0 ' To display data through serial comm
DHT_Port VAR PORTB.7 ' PIC's port to DHT11's "OUT" pin
DHT_PWR VAR PORTC.7 ' power supply for DHT11's module - "+" pin (2mA)
' ====== INTIALIZE ================================================== ===============================
HIGH SerialData 'set port High to avoid sending serial "garbage"
' ====== PROGRAM START ================================================== ===========================
MAIN:
' Power-up DHT11
HIGH DHT_PWR ' switch ON DHT11 sensor
HIGH DHT_Port ' make the PIC's port an Output
PAUSE 1000 ' let DHT11 settle
' Send Start Signal to DHT11
DHT_Port = 0 : PAUSE 20 ' set LOW at least 18ms to let DHT11 detect the signal
DHT_Port = 1 : PAUSEUS 30 ' set 20-40µs HIGH and wait for DHT11's response
' DHT11 responds to MCU now in going 80µs LOW and 80µs HIGH before sending data
WHILE DHT_Port = 0 : WEND ' DHT11 goes LOW - just wait until (~80µs) it goes HIGH
' Once gone HIGH, DHT11 waits 80µs and then starts to send data
' Receive 32 data bits (out of 40 - last 8bits are checksum - not used)
FOR x = 31 TO 0 STEP -1
PULSIN DHT_Port, 1, DHT_Data[x]
NEXT x
' Switch OFF DHT11 sensor (not mandatory but gives better RH results)
LOW DHT_PWR
' Convert pulses length into binary values (26-28µs = "0", 70µs = "1")
FOR x = 31 TO 0 STEP -1
IF DHT_Data[x] > 10 THEN ' 50µs (somewhere between 28 and 70µs)
DHT_Data[x] = 1 ' is it greater than 50µs so it's a "1"
ELSE
DHT_Data[x] = 0 ' is it smaller than 50µs so it's a "0"
ENDIF
NEXT x
' Convert bits to variables
HUMIDITY.7 = DHT_Data[31]
HUMIDITY.6 = DHT_Data[30]
HUMIDITY.5 = DHT_Data[29]
HUMIDITY.4 = DHT_Data[28]
HUMIDITY.3 = DHT_Data[27]
HUMIDITY.2 = DHT_Data[26]
HUMIDITY.1 = DHT_Data[25]
HUMIDITY.0 = DHT_Data[24]
TEMPERATURE.7 = DHT_Data[15]
TEMPERATURE.6 = DHT_Data[14]
TEMPERATURE.5 = DHT_Data[13]
TEMPERATURE.4 = DHT_Data[12]
TEMPERATURE.3 = DHT_Data[11]
TEMPERATURE.2 = DHT_Data[10]
TEMPERATURE.1 = DHT_Data[9]
TEMPERATURE.0 = DHT_Data[8]
' Display temperature and humidity
SEROUT2 SerialData,84,["T: ", DEC TEMPERATURE, "C RH: ", DEC HUMIDITY, "%", 13,10] '9600,8,N,1
' Now, goto low power for 1 minute
SLEEP 60 ' in seconds - wake-up every minute
GOTO MAIN
'======= CIRCUITRY ================================================== ===============================
' [PIC]
'PORTA.0[19] ICSPDAT / Serial data out (PICkit2's UART tool RX pin)
'PORTA.1[18] ICSPCLK
'PORTA.2[17]
'PORTA.3[04] MCLR
'PORTA.4[03] OSC2 - 8Mhz Xtal
'PORTA.5[02] OSC1 - 8Mhz Xtal
'
'PORTB.4[13]
'PORTB.5[12]
'PORTB.6[11]
'PORTB.7[10] DHT11's "OUT" pin with 10k pull-up resistor
'
'PORTC.0[16]
'PORTC.1[15]
'PORTC.2[14]
'PORTC.3[07]
'PORTC.4[06]
'PORTC.5[05]
'PORTC.6[08]
'PORTC.7[09] DHT11's module power supply pin "+"
Here is my code to read temperature and humidity from a DHT11 sensor. It has also the SLEEP functionality.
I tried to make it as simple and clear as possible :)
' ====== PIC 16F690 FUSES ================================================== ========================
' External oscillator 8MHz
@ __config _FCMEN_OFF &_IESO_OFF &_CPD_OFF &_WDT_OFF &_HS_OSC &_BOR_OFF &_CP_OFF &_PWRTE_OFF &_MCLRE_OFF
' ====== REGISTERS ================================================== ===============================
' Registers 76543210
OPTION_REG = %10000000 ' PORT A&B Pull-Ups and Prescaler (def.: %11111111)
OSCCON = %00000000 ' External (def.: %01101000)
WDTCON = %00001001 ' Enable WatchDog (the REGISTER, not the fuse) for SLEEP
' ====== DEFINES ================================================== =================================
DEFINE OSC 8 ' don't forget the external oscillator
' ====== VARIABLES ================================================== ===============================
DHT_Data VAR BYTE [32] ' hold bitwise humidity and temperature data
HUMIDITY VAR BYTE ' holds humidity value
TEMPERATURE VAR BYTE ' holds temperature value
x VAR BYTE ' a counter
SerialData VAR PORTA.0 ' To display data through serial comm
DHT_Port VAR PORTB.7 ' PIC's port to DHT11's "OUT" pin
DHT_PWR VAR PORTC.7 ' power supply for DHT11's module - "+" pin (2mA)
' ====== INTIALIZE ================================================== ===============================
HIGH SerialData 'set port High to avoid sending serial "garbage"
' ====== PROGRAM START ================================================== ===========================
MAIN:
' Power-up DHT11
HIGH DHT_PWR ' switch ON DHT11 sensor
HIGH DHT_Port ' make the PIC's port an Output
PAUSE 1000 ' let DHT11 settle
' Send Start Signal to DHT11
DHT_Port = 0 : PAUSE 20 ' set LOW at least 18ms to let DHT11 detect the signal
DHT_Port = 1 : PAUSEUS 30 ' set 20-40µs HIGH and wait for DHT11's response
' DHT11 responds to MCU now in going 80µs LOW and 80µs HIGH before sending data
WHILE DHT_Port = 0 : WEND ' DHT11 goes LOW - just wait until (~80µs) it goes HIGH
' Once gone HIGH, DHT11 waits 80µs and then starts to send data
' Receive 32 data bits (out of 40 - last 8bits are checksum - not used)
FOR x = 31 TO 0 STEP -1
PULSIN DHT_Port, 1, DHT_Data[x]
NEXT x
' Switch OFF DHT11 sensor (not mandatory but gives better RH results)
LOW DHT_PWR
' Convert pulses length into binary values (26-28µs = "0", 70µs = "1")
FOR x = 31 TO 0 STEP -1
IF DHT_Data[x] > 10 THEN ' 50µs (somewhere between 28 and 70µs)
DHT_Data[x] = 1 ' is it greater than 50µs so it's a "1"
ELSE
DHT_Data[x] = 0 ' is it smaller than 50µs so it's a "0"
ENDIF
NEXT x
' Convert bits to variables
HUMIDITY.7 = DHT_Data[31]
HUMIDITY.6 = DHT_Data[30]
HUMIDITY.5 = DHT_Data[29]
HUMIDITY.4 = DHT_Data[28]
HUMIDITY.3 = DHT_Data[27]
HUMIDITY.2 = DHT_Data[26]
HUMIDITY.1 = DHT_Data[25]
HUMIDITY.0 = DHT_Data[24]
TEMPERATURE.7 = DHT_Data[15]
TEMPERATURE.6 = DHT_Data[14]
TEMPERATURE.5 = DHT_Data[13]
TEMPERATURE.4 = DHT_Data[12]
TEMPERATURE.3 = DHT_Data[11]
TEMPERATURE.2 = DHT_Data[10]
TEMPERATURE.1 = DHT_Data[9]
TEMPERATURE.0 = DHT_Data[8]
' Display temperature and humidity
SEROUT2 SerialData,84,["T: ", DEC TEMPERATURE, "C RH: ", DEC HUMIDITY, "%", 13,10] '9600,8,N,1
' Now, goto low power for 1 minute
SLEEP 60 ' in seconds - wake-up every minute
GOTO MAIN
'======= CIRCUITRY ================================================== ===============================
' [PIC]
'PORTA.0[19] ICSPDAT / Serial data out (PICkit2's UART tool RX pin)
'PORTA.1[18] ICSPCLK
'PORTA.2[17]
'PORTA.3[04] MCLR
'PORTA.4[03] OSC2 - 8Mhz Xtal
'PORTA.5[02] OSC1 - 8Mhz Xtal
'
'PORTB.4[13]
'PORTB.5[12]
'PORTB.6[11]
'PORTB.7[10] DHT11's "OUT" pin with 10k pull-up resistor
'
'PORTC.0[16]
'PORTC.1[15]
'PORTC.2[14]
'PORTC.3[07]
'PORTC.4[06]
'PORTC.5[05]
'PORTC.6[08]
'PORTC.7[09] DHT11's module power supply pin "+"