Raspberry Pi仿真扩展板

#!/usr/bin/python

# Example program to read data from MCP3008 10 bit ADC

import spidev
import time
import os
 
# Open SPI bus
spi = spidev.SpiDev()
spi.open(0,0)
 
# Function to read SPI data from MCP3008 chip
# Channel must be an integer 0-7
def ReadChannel(channel):
  adc = spi.xfer2([1,(8+channel)<<4,0])
  data = ((adc[1]&3) << 8) + adc[2]
  return data
 
# Function to convert data to voltage level,
# rounded to specified number of decimal places.
def ConvertVolts(data,places):
  volts = (data * 3.3) / float(1023)
  volts = round(volts,places)
  return volts
 
# Define sensor channels
first_channel = 0
second_channel  = 1
 
# Define delay between readings
delay = 5

print "------------------------------------------------------"
 
while True:
 
  # Read the first channel data
  first_level = ReadChannel(first_channel)
  first_channel_volts = ConvertVolts(first_level,2)
 
  # Read the second channel data
  second_level = ReadChannel(second_channel)
  second_channel_volts = ConvertVolts(second_level,2)
  
 
  # Print out results
  print "------------------------------------------------------"
  print("First ADC channel: {} ({}V)".format(first_level,first_channel_volts))
  print("Second ADC channel : {} ({}V)".format(second_level,second_channel_volts))
 
  # Wait before repeating loop
  time.sleep(delay)

# Example program to read data from DS18B20
# This code taken from
# https://kropochev.com/?go=all/raspberry-pi-and-onewire-sensor/

import os
import glob
import time

os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')

base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '10*')[0]
device_file = device_folder + '/w1_slave'

def read_temp_raw():
    f = open(device_file, 'r')
    lines = f.readlines()
    f.close()
    return lines

def read_temp():
    lines = read_temp_raw()
    while lines[0].strip()[-3:] != 'YES':
        time.sleep(0.2)
        lines = read_temp_raw()
    equals_pos = lines[1].find('t=')
    if equals_pos != -1:
        temp_string = lines[1][equals_pos+2:]
        temp_c = float(temp_string) / 1000.0
        temp_f = temp_c * 9.0 / 5.0 + 32.0
        return temp_c, temp_f

while True:
    print(read_temp())
    time.sleep(1)

— 1 Wire settings:
— Raspbian wheezy

Enter command in console:
pi@raspberrypi~$ sudo modprobe w1-gpio
pi@raspberrypi~$ sudo modprobe w1_therm

Then check sensor in system:
pi@raspberrypi ~ $ sudo ls /sys/bus/w1/devices/w1_bus_master1/

You can see the tabel below entered comman and
there you should find HEX like 28-000002da8328;
This is DS18B20 address;

Next read the data from DS18B20 sensor using command:
pi@raspberrypi ~ $ cat /sys/bus/w1/devices/w1_bus_master1/28-000002da8328/w1_sla

And you are going see temperature in console like:
6f 01 4b 46 7f ff 01 10 67: crc=67 YES
6f 01 4b 46 7f ff 01 10 67 t=22937

t=22937 — you should divide this number on 1000 and you will have temperature in Celsius;

— Raspbian Jezzy

Enter command:
pi@raspberrypi~$ sudo nano /boot/config.txt

On next step you should write in config file
dtoverlay=w1-gpio,gpiopin=4
dtoverlay=w1-gpio-pullup

Then you should reboot your raspberry Pi;

— I2C Real Time Clock settings:
— Update your system if it needed and install i2c-tools:
pi@raspberrypi~$ sudo apt-get update
pi@raspberrypi~$ sudo apt-get -y upgrade
pi@raspberrypi~$ sudo apt-get i2c-tools:

Enter command:
pi@raspberrypi~$ sudo nano /etc/modules
Add these lines:
i2c-bcm2708
i2c-dev
rtc_ds1307

Comment one line in file:
pi@raspberrypi~$ sudo nano /etc/modprobe.d/raspi-blacklist.conf
Add # Symbol in beginning of line

blacklist i2c-bcm2708
________________________________________________________
Reboot system;
Enter command:
pi@raspberrypi~$ sudo lsmod

You will see lines like:
rtc_ds1307 7715 0
i2c_dev 5277 0
i2c_bcm2708 4719 0
________________________________________________________

Get DS1307 address:
pi@raspberrypi~$ sudo i2cdetect -y 1

You will see table in console:

0 1 2 3 4 5 6 7 8 9 a b c d e f
00: — -- — -- — -- — -- — -- — -- — 10: — -- — -- — -- — -- — -- — -- — -- — --
20: — -- — -- — -- — -- — -- — -- — -- — --
30: — -- — -- — -- — -- — -- — UU — -- — --
40: — -- — -- — -- — -- — -- — -- — -- — --
50: — -- — -- — -- — -- — -- — -- — -- — --
60: — -- — -- — -- — -- 68 — -- — -- — -- — 70: — -- — -- — -- — --

In address 0x3b some device without driver and 0x68 perhaps DS1307 clock address.

Enter command:
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device

Read clock:
pi@raspberrypi~$ sudo hwclock -r

Set time:
pi@raspberrypi~$ sudo hwclock -w
Set system time from RTC:
pi@raspberrypi~$ sudo hwclock -s

Automatic RTC start;
Add lines in /etc/rc.local file

echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
sudo hwclock -s
Before last line in file looks like:

exit 0
— Uart settings:
— Back up files:
cp /boot/cmdline.txt /boot/cmdline.bak
cp /etc/inittab /etc/inittab.bak

Delete «console=ttyAMA0,115200» «kgdboc=ttyAMA0,115200» lines from configuration file:
pi@raspberrypi~$ nano /boot/cmdline.txt

Comment last line looks like «T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100: in /etc/inittab file: using # symbol:
pi@raspberrypi~$ nano /etc/inittab