#!/usr/bin/python3 # Running vacuum pressure graph on four channels. # May 3 2021 # Use with extra pullup board for i2c-0 # Must add this to /boot/config.txt to enable i2c-0: # dtparam=i2c_vc=on # Also in raspi-config, disable camera module and enable I2c. # # List I2C devices: Normal port: # i2cdetect -y 1 # # List I2C detices on extra port (that needs above confi changes and pull ups) # i2cdetect -y 0 import smbus import time from ctypes import c_short from ctypes import c_byte from ctypes import c_ubyte DEVICE = 0x76 # Default device I2C address bus = smbus.SMBus(1) # Rev 2 Pi, Pi 2 & Pi 3 uses bus 1 # Rev 1 Pi uses bus 0 def getShort(data, index): # return two bytes from data as a signed 16-bit value return c_short((data[index+1] << 8) + data[index]).value def getUShort(data, index): # return two bytes from data as an unsigned 16-bit value return (data[index+1] << 8) + data[index] def getChar(data,index): # return one byte from data as a signed char result = data[index] if result > 127: result -= 256 return result def getUChar(data,index): # return one byte from data as an unsigned char result = data[index] & 0xFF return result def readBME280ID(addr=DEVICE): # Chip ID Register Address REG_ID = 0xD0 (chip_id, chip_version) = bus.read_i2c_block_data(addr, REG_ID, 2) return (chip_id, chip_version) def readBME280All(addr=DEVICE): # Register Addresses REG_DATA = 0xF7 REG_CONTROL = 0xF4 REG_CONFIG = 0xF5 REG_CONTROL_HUM = 0xF2 REG_HUM_MSB = 0xFD REG_HUM_LSB = 0xFE # Oversample setting - page 27 OVERSAMPLE_TEMP = 2 OVERSAMPLE_PRES = 2 MODE = 1 # Oversample setting for humidity register - page 26 OVERSAMPLE_HUM = 2 bus.write_byte_data(addr, REG_CONTROL_HUM, OVERSAMPLE_HUM) control = OVERSAMPLE_TEMP<<5 | OVERSAMPLE_PRES<<2 | MODE bus.write_byte_data(addr, REG_CONTROL, control) # Read blocks of calibration data from EEPROM # See Page 22 data sheet cal1 = bus.read_i2c_block_data(addr, 0x88, 24) cal2 = bus.read_i2c_block_data(addr, 0xA1, 1) cal3 = bus.read_i2c_block_data(addr, 0xE1, 7) # Convert byte data to word values dig_T1 = getUShort(cal1, 0) dig_T2 = getShort(cal1, 2) dig_T3 = getShort(cal1, 4) dig_P1 = getUShort(cal1, 6) dig_P2 = getShort(cal1, 8) dig_P3 = getShort(cal1, 10) dig_P4 = getShort(cal1, 12) dig_P5 = getShort(cal1, 14) dig_P6 = getShort(cal1, 16) dig_P7 = getShort(cal1, 18) dig_P8 = getShort(cal1, 20) dig_P9 = getShort(cal1, 22) dig_H1 = getUChar(cal2, 0) dig_H2 = getShort(cal3, 0) dig_H3 = getUChar(cal3, 2) dig_H4 = getChar(cal3, 3) dig_H4 = (dig_H4 << 24) >> 20 dig_H4 = dig_H4 | (getChar(cal3, 4) & 0x0F) dig_H5 = getChar(cal3, 5) dig_H5 = (dig_H5 << 24) >> 20 dig_H5 = dig_H5 | (getUChar(cal3, 4) >> 4 & 0x0F) dig_H6 = getChar(cal3, 6) # Wait in ms (Datasheet Appendix B: Measurement time and current calculation) wait_time = 1.25 + (2.3 * OVERSAMPLE_TEMP) + ((2.3 * OVERSAMPLE_PRES) + 0.575) + ((2.3 * OVERSAMPLE_HUM)+0.575) time.sleep(wait_time/1000) # Wait the required time # Read temperature/pressure/humidity data = bus.read_i2c_block_data(addr, REG_DATA, 8) pres_raw = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4) temp_raw = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4) hum_raw = (data[6] << 8) | data[7] #Refine temperature var1 = ((((temp_raw>>3)-(dig_T1<<1)))*(dig_T2)) >> 11 var2 = (((((temp_raw>>4) - (dig_T1)) * ((temp_raw>>4) - (dig_T1))) >> 12) * (dig_T3)) >> 14 t_fine = var1+var2 temperature = float(((t_fine * 5) + 128) >> 8); # Refine pressure and adjust for temperature var1 = t_fine / 2.0 - 64000.0 var2 = var1 * var1 * dig_P6 / 32768.0 var2 = var2 + var1 * dig_P5 * 2.0 var2 = var2 / 4.0 + dig_P4 * 65536.0 var1 = (dig_P3 * var1 * var1 / 524288.0 + dig_P2 * var1) / 524288.0 var1 = (1.0 + var1 / 32768.0) * dig_P1 if var1 == 0: pressure=0 else: pressure = 1048576.0 - pres_raw pressure = ((pressure - var2 / 4096.0) * 6250.0) / var1 var1 = dig_P9 * pressure * pressure / 2147483648.0 var2 = pressure * dig_P8 / 32768.0 pressure = pressure + (var1 + var2 + dig_P7) / 16.0 # Refine humidity humidity = t_fine - 76800.0 humidity = (hum_raw - (dig_H4 * 64.0 + dig_H5 / 16384.0 * humidity)) * (dig_H2 / 65536.0 * (1.0 + dig_H6 / 67108864.0 * humidity * (1.0 + dig_H3 / 67108864.0 * humidity))) humidity = humidity * (1.0 - dig_H1 * humidity / 524288.0) if humidity > 100: humidity = 100 elif humidity < 0: humidity = 0 return temperature/100.0,pressure/100.0,humidity def ReadBmeAll(): (chip_id, chip_version) = readBME280ID() print ("Chip ID :", chip_id) print ("Version :", chip_version) temperature,pressure,humidity = readBME280All() print ("Temperature : ", temperature, "C") print ("Pressure : ", pressure, "hPa") print ("Humidity : ", humidity, "%") temps=[0,0,0,0] humid=[0,0,0,0] press=[0,0,0,0] for x in range(4): addr = 0x76 if x & 1: addr = 0x77 if x == 2: bus = smbus.SMBus(0) try: temps[x],press[x],humid[x] = readBME280All(addr) except: temps[x] = press[x] = humid[x] = float("nan") # Use try catch to still log the other sensor in case one of them fails. ts = "" hs = "" ps = "" chans = ["I2C1 0x66","I2C1 0x67","I2C0 0x66","I2C0 0x67"] for x in range(4): print ("%s: %5.2f %5.2f %7.2f"%(chans[x], temps[x], humid[x], press[x])) ts = ts + "%5.2f, "%temps[x] hs = hs + "%4.1f, "%humid[x] ps = ps + "%7.2f,"%press[x] tm = time.localtime() timestr = time.strftime("%d-%b-%y %H:%M:%S, ", tm) logstr = timestr + ts+" "+hs+" "+ps print (logstr) linelen = 161 print("Temperature graph, celcius") print ("14 deg 15 deg 16 deg 17 deg 18 deg 19 deg 20 deg") while 1: graph = [-1]*linelen bus = smbus.SMBus(1) for x in range (4): addr = 0x76 if x & 1: addr = 0x77 if x >= 2: bus = smbus.SMBus(0) try: temps[x],press[x],humid[x] = readBME280All(addr) except: continue #index = int((1007-press[x])*2) index = int ((temps[x]-14)*20) if index < 0: index = 0 if index >= linelen: index = linelen-1 if graph[index] < 0: graph[index] = x else: graph[index] = 9 out = "" for x in range (0,linelen): if graph[x] >= 0: if graph[x] > 3: out = out + "#" else: out = out + str(graph[x]) else: if x % 10 == 0: if x % 20 == 0: out = out + '.' else: out = out + " " else: out = out + " " print (out) time.sleep(0.2) #with open("/home/pi/templog.txt", "a") as myfile: # myfile.write(logstr+"\n")