Python PC Printer Port Controls Serial LCD Display
Here we've connected a 2X16 LCD display to the PC printer port. A count from 0-255 will be displayed as binary on the 8 LEDs and as decimal, octal, and hex on the LCD. The electronics works identical to earlier projects listed below that were written in C.
Here we demonstrate to output serial data to an outside device.
- Connect Arduino to LCD Display with 74164 Shift Register
- Arduino with LCD Display and DS18B20 Temperature Sensor
- PIC18F2550 BOLT with Serial LCD Display
Connect as serial LCD display as follows:
# Bit_out Pin 1-2 Sn74164 # CLK Pin 9 Sn74164 - clock bit - LOW to HIGH to LOW # RS Pin 4 LCD - LOW command; HIGH ASCII # E Pin 6 LCD - clock data into LCD - HIGH to LOW to HIGH # init i/o pins p.setDataStrobe(0) # Pin 1 use as CLK 74164 pin 9 p.setAutoFeed(0) # Pin 14 use as data bit for 74164 pins 1-2 p.setInitOut(1) # Pin 16 use as E LCD pin 6 p.setSelect(0) # Pin 17 use as RS LCD pin 4
The program is written in Python and runs under Linux. To use this one must setup a module pyparallel. How to set this up is on my webpage Programming the PC Printer Port in Python
#!/usr/bin/env python # File pportlcd.py # https://bristolwatch.com/pport/index.htm # By Lewis Loflin - email@example.com # Must use my version of pyparallel on website for p.data(). # Connects 74165 shift register and LCD display # Has 8 LEDs in data port Db25 pins 2-9. # This can be done from Idle, Geany, or command line # Set Geany to use lxterminal if available. import parallel import time p = parallel.Parallel() Line1 = 0x80 # location LCD row 0 col 0 or line 1 Line2 = 0xC0 # location LCD row 1 col 0 or line 2 # Bit_out Pin 1-2 Sn74164 # CLK Pin 9 Sn74164 - clock bit - LOW to HIGH to LOW # RS Pin 4 LCD - LOW command; HIGH ASCII # E Pin 6 LCD - clock data into LCD - HIGH to LOW to HIGH # init i/o pins p.setDataStrobe(0) # Pin 1 use as CLK orange wire p.setAutoFeed(0) # Pin 14 use as data bit for 74164 yellow p.setInitOut(1) # Pin 16 use as E brown wire p.setSelect(0) # Pin 17 use as RS white wire def pulseCLK(): p.setDataStrobe(1) #time.sleep(.01) p.setDataStrobe(0) return def pulseE(): p.setInitOut(0) #time.sleep(.01) p.setInitOut(1) return # MSB out first! def ssrWrite(value): for x in range(0,8): temp = value & 0x80 if temp == 0x80: p.setAutoFeed(1) # set data bit HIGH else: p.setAutoFeed(0) pulseCLK() value = value << 0x01 # shift left time.sleep(.001) p.setDataStrobe(0) p.setAutoFeed(0) return def initLCD(): p.setSelect(0) # RS LOW ssrWrite(0x38) # setup for 2 lines pulseE() ssrWrite(0x0F) # blinking cursor pulseE() clearLCD() Home() return def clearLCD(): p.setSelect(0) # RS LOW ssrWrite(0x01) # clear pulseE() return def Home(): p.setSelect(0) # RS LOW ssrWrite(0x02) # home pulseE() return def gotoLocation(val): p.setSelect(0) # RS LOW if val < 0x80: val = 0x80 ssrWrite(val) pulseE() return def writeString(myString): i = len(myString) p.setSelect(1) # Pin 17 RS - HIGH is ASCII for x in range(0,i): y = ord(myString[x]) ssrWrite(y) pulseE() p.setSelect(0) # Pin 17 RS LOW return # convert an 8-bit number to a binary string def convBinary(value): binaryValue = 'b' for x in range(0,8): temp = value & 0x80 if temp == 0x80: binaryValue = binaryValue + '1' else: binaryValue = binaryValue + '0' value = value << 1 return binaryValue initLCD() # print in binary on LCD and LEDs print "Now counting in binary on LCD and LEDs - please wait..." for j in range(0, 256): myStr1 = convBinary(j) writeString(myStr1) p.setData(j) # write to data port time.sleep(.1) Home() clearLCD() # clr LCD print # print j in HEX, OCT, base 10 # print binary on LEDs print "Counting int j in HEX, OCT, base 10 on LCD" print "and in binary on LEDs - please wait..." for j in range(0, 256): p.setData(j) writeString('J = ' + str(j)) # base 10 gotoLocation(Line1 + 8) writeString('OCT ' + oct(j)) # print octal gotoLocation(Line2) writeString('HEX ' + hex(j)) # print hex time.sleep(.1) Home() p.setData(0) # LEDs all off clearLCD() # clr LCD gotoLocation(Line1) writeString("Finished!") gotoLocation(Line2) writeString("Good by!") print print "Finished, good by." exit
Below are listed a series of projects using pyparallel and electronics. Starting with routines I wrote to aid students I'd advise walking through this in sequence. Have fun and send comments and/or corrections to firstname.lastname@example.org.
- Introduction to Python Bitwise Operations
- Python Bitwise Operations by Example
- Using the PC Printer Port series:
- Programming the PC Printer Port in Python
- Additional Commands for Py-Parallel
- Controlling Data Bits on the PC Parallel Port
- Connecting Switches to the PC Printer Port with Python
- Reading an Analog Voltage Through the PC Printer Port Part 1
- Reading an Analog Voltage Through the PC Printer Port Part 2
- Controlling a Serial LCD Display on a PC Printer Port with Python
- Serial ADC and LCD Display with PC Printer Port with Python
- Controlling MAX7219 LED Display with PC Printer Port with Python
- MAX7219 8-Digit LED Display and Serial ADC in Python
- Project pages:
- Part 1: Read Arduino with PC Printer Port
- Part 2: Better way to Read Arduino Through the PC Printer Port
- Part 3: Read-Write an Arduino Through a PC Printer Port
- Part 4: Control LCD Display and Arduino from the PC Printer Port
- Arduino sketches needed by programs:
- pportArduino1.ino read only after reset.
- pportArduino2.ino reset once and multiple reads.
- pportArduino3.ino reset once read write Arduino infinite times - multiple commands.
- Related Raspberry Pi projects:
- Connect Serial LCD to Raspberry Pi
- Serial Read from Arduino to Raspberry Pi
- Arduino Raspberry Pi Interface with LCD Display
Printer Port Interfacing Videos:
Connect Electronics to PC printer Port with Python
Setup PC Printer Port with Python-Linux
Use PC Printer Port to Read Analog Voltage
Read-Write Arduino ADC PWN with Printer Port
Printer Port to Serial LCD Display
Connect Arduino to PC Printer Port for advanced control