LCD顯示GPS時鐘[嵌入式系統]

                            夏任務102：作一個GPS鍾

 

實驗要求

　　用RPi的串口鏈接一個GPS模塊，從GPS獲得實時時間，在7段數碼管或LCD上顯示

實驗工具：

Raspberry Pi Model B主機，

8G c10 SD卡，

USB充電線，

電源需自備5v 1A電源充電頭一個

PC機一臺（這裏用的操做系統是windows7 64bit旗艦版）

LED面板

GPS模塊+串口線

 

實驗步驟：

1. 鏈接電路線路

• 　　LCD鏈接參照blog：http://www.freemindworld.com/blog/2013/130310_raspberry_pi_with_lcd.shtml
• 　　GPS鏈接RPI

　　　　　　　　GPS板G3203:

　　　　　　　　　　VDD->RPi的3.3V

　　　　　　　　　　TXD->RPi的RXD

　　　　　　　　　　GND->RPi的GND

 

 

　　2。在樹莓派上安裝pyserial：

下載地址：http://sourceforge.net/projects/pyserial/files/pyserial/2.5/

解壓後進入目錄 運行

  python setup.py install

　　

 

1. 編寫代碼Adafruit_CharLCD.py：

　　　　　　（LCD顯示代碼引自git clone https://github.com/lifanxi/rpimenu.git）

#!/usr/bin/python   # # based on code from lrvick and LiquidCrystal # lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py # LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp #   from time import sleep import serial import traceback import os import commands import string   class Adafruit_CharLCD:       # commands     LCD_CLEARDISPLAY            = 0x01     LCD_RETURNHOME               = 0x02     LCD_ENTRYMODESET           = 0x04     LCD_DISPLAYCONTROL              = 0x08     LCD_CURSORSHIFT               = 0x10     LCD_FUNCTIONSET               = 0x20     LCD_SETCGRAMADDR         = 0x40     LCD_SETDDRAMADDR         = 0x80       # flags for display entry mode     LCD_ENTRYRIGHT          = 0x00     LCD_ENTRYLEFT             = 0x02     LCD_ENTRYSHIFTINCREMENT = 0x01     LCD_ENTRYSHIFTDECREMENT        = 0x00       # flags for display on/off control     LCD_DISPLAYON             = 0x04     LCD_DISPLAYOFF           = 0x00     LCD_CURSORON             = 0x02     LCD_CURSOROFF            = 0x00     LCD_BLINKON          = 0x01     LCD_BLINKOFF         = 0x00       # flags for display/cursor shift     LCD_DISPLAYMOVE              = 0x08     LCD_CURSORMOVE              = 0x00       # flags for display/cursor shift     LCD_DISPLAYMOVE              = 0x08     LCD_CURSORMOVE              = 0x00     LCD_MOVERIGHT           = 0x04     LCD_MOVELEFT              = 0x00       # flags for function set     LCD_8BITMODE               = 0x10     LCD_4BITMODE               = 0x00     LCD_2LINE                 = 0x08     LCD_1LINE                 = 0x00     LCD_5x10DOTS          = 0x04     LCD_5x8DOTS            = 0x00           def show_time(i,interval):              global num              while True:                     try:                            show(num)                     except Exception as ep:                            print ep       def __init__(self, pin_rs=4, pin_e=25, pins_db=[17, 18, 27, 22], GPIO = None):       # Emulate the old behavior of using RPi.GPIO if we haven't been given       # an explicit GPIO interface to use       if not GPIO:           import RPi.GPIO as GPIO           self.GPIO = GPIO         self.pin_rs = pin_rs         self.pin_e = pin_e         self.pins_db = pins_db           self.GPIO.setmode(GPIO.BCM)         self.GPIO.setup(self.pin_e, GPIO.OUT)         self.GPIO.setup(self.pin_rs, GPIO.OUT)           for pin in self.pins_db:             self.GPIO.setup(pin, GPIO.OUT)         self.write4bits(0x33) # initialization       self.write4bits(0x32) # initialization       self.write4bits(0x28) # 2 line 5x7 matrix       self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor       self.write4bits(0x06) # shift cursor right         self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF         self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS       self.displayfunction |= self.LCD_2LINE         """ Initialize to default text direction (for romance languages) """       self.displaymode =  self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT       self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) #  set the entry mode           self.clear()         def begin(self, cols, lines):         if (lines > 1):              self.numlines = lines                 self.displayfunction |= self.LCD_2LINE              self.currline = 0         def home(self):         self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero       self.delayMicroseconds(3000) # this command takes a long time!             def clear(self):         self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display       self.delayMicroseconds(3000) # 3000 microsecond sleep, clearing the display takes a long time         def setCursor(self, col, row):         self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ]         if ( row > self.numlines ):              row = self.numlines - 1 # we count rows starting w/0         self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))         def noDisplay(self):       """ Turn the display off (quickly) """         self.displaycontrol &= ~self.LCD_DISPLAYON       self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)         def display(self):       """ Turn the display on (quickly) """         self.displaycontrol |= self.LCD_DISPLAYON       self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)         def noCursor(self):       """ Turns the underline cursor on/off """         self.displaycontrol &= ~self.LCD_CURSORON       self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)         def cursor(self):       """ Cursor On """         self.displaycontrol |= self.LCD_CURSORON       self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)         def noBlink(self):       """ Turn on and off the blinking cursor """         self.displaycontrol &= ~self.LCD_BLINKON       self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)         def noBlink(self):       """ Turn on and off the blinking cursor """         self.displaycontrol &= ~self.LCD_BLINKON       self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)         def DisplayLeft(self):       """ These commands scroll the display without changing the RAM """         self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)         def scrollDisplayRight(self):       """ These commands scroll the display without changing the RAM """         self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT);         def leftToRight(self):       """ This is for text that flows Left to Right """         self.displaymode |= self.LCD_ENTRYLEFT       self.write4bits(self.LCD_ENTRYMODESET | self.displaymode);         def rightToLeft(self):       """ This is for text that flows Right to Left """       self.displaymode &= ~self.LCD_ENTRYLEFT       self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)         def autoscroll(self):       """ This will 'right justify' text from the cursor """         self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT       self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)         def noAutoscroll(self):       """ This will 'left justify' text from the cursor """         self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT       self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)         def write4bits(self, bits, char_mode=False):         """ Send command to LCD """         self.delayMicroseconds(1000) # 1000 microsecond sleep           bits=bin(bits)[2:].zfill(8)           self.GPIO.output(self.pin_rs, char_mode)           for pin in self.pins_db:             self.GPIO.output(pin, False)           for i in range(4):             if bits[i] == "1":                 self.GPIO.output(self.pins_db[::-1][i], True)         self.pulseEnable()           for pin in self.pins_db:             self.GPIO.output(pin, False)           for i in range(4,8):             if bits[i] == "1":                 self.GPIO.output(self.pins_db[::-1][i-4], True)         self.pulseEnable()         def delayMicroseconds(self, microseconds):       seconds = microseconds / float(1000000)    # divide microseconds by 1 million for seconds       sleep(seconds)         def pulseEnable(self):       self.GPIO.output(self.pin_e, False)       self.delayMicroseconds(1)              # 1 microsecond pause - enable pulse must be > 450ns       self.GPIO.output(self.pin_e, True)       self.delayMicroseconds(1)              # 1 microsecond pause - enable pulse must be > 450ns       self.GPIO.output(self.pin_e, False)       self.delayMicroseconds(1)              # commands need > 37us to settle         def message(self, text):         """ Send string to LCD. Newline wraps to second line"""           for char in text:             if char == '\n':                 self.write4bits(0xC0) # next line             else:                 self.write4bits(ord(char),True)     if __name__ == '__main__':         lcd = Adafruit_CharLCD()       mest="Lab102 GPS Clock \n time: " 　　message="show"       while True:              try:                     tmp=ser.readline()                           if tmp.find('GPRMC')==1:                            buf = tmp.split(',')                            tim = buf[1]                            print tim                            num = tim[0:8]                            message= mest+num                            lcd.clear()                         lcd.message(message)                   except Exception as e:                     print e                     #ser.close()                     ser = serial.Serial('/dev/ttyAMA0')

 

　　　　　　3.SSH鏈接樹莓派，運行該代碼,LCD顯示如圖：

　　　　　　　　

sudo python Adafruit_CharLCD.py