[ Lab11] Character LCM

1. [Lab11] Character LCM • Deploy LCM • Example • Exercise

2. Character LCM • In this lecture, we use YJD1602A-1 as LCD module to display 16 characters, 2 lines information.

3. Character LCM (cont.)

4. Character LCM (cont.) • YJD1602A-1 data sheet • 4-bits or 8-bits interface avaliable • Power supply: 5V±10%

5. Character LCM (cont.) • Vss : Connect to GND. • VDD: Connect to P9_7, +5V from BBIO. • V0: For adjusting the contrast. Connect to GND. • RS: Register Select. Connect to P8_12, control by program. • R/W: Read from LCM or write to LCM. Connect to GND for write only.

6. Character LCM (cont.) • E: Enable Signal Signal, Connect to P8_14, control by program. • DB0-DB3: Data bus used in 8 bits transfer, did not use in this lecture. • DB4-DB7: Data bus for both 4 and 8 bits transfer. Connect to P8_16, P8_18, P8_20, P8_22. • BLA and K: Power for BackLight. A for +5V and K for GND.

7. Character LCM (cont.) • We are going to implement functions Including: • lcdcommand(str) for giving instructions to LCM • lcdprint(str) for giving string to LCM. • setup() for initial setting. • loop() for discribe main function’s action control.

8. Character LCM (cont.) • Example: • Show a string and Beaglebone uptime on the LCM.

9. Character LCM (cont.) Source code: from bbio import * from datetime import timedelta import time import datetime import os import sys usleep = lambda x : time.sleep(x/1000000.0) #generate a microsecond delay iomap = [GPIO1_12, GPIO0_26, GPIO1_5, GPIO1_31, GPIO2_1, GPIO1_14]

10. Character LCM (cont.) def lcdcommand(str) : digitalWrite(iomap[1], 1) usleep(500) digitalWrite(iomap[0], 0) iteration = 0 for idr in str: digitalWrite(iomap[iteration+2], int(idr)) iteration = iteration + 1 if iteration == 4: iteration = 0 usleep(100) digitalWrite(iomap[1], LOW) usleep(100) digitalWrite(iomap[1], HIGH) usleep(500) return

11. Character LCM (cont.) def lcdprint(str) : for char in str: bitmap = bin (ord(char)) [2:].zfill(8) digitalWrite(iomap[1], 1) usleep(20) digitalWrite(iomap[0], 1) iteration = 0 for idr in bitmap: digitalWrite(iomap[iteration+2], int(idr)) iteration+= 1 if iteration == 4: iteration = 0; usleep(20) digitalWrite(iomap[1], LOW) usleep(20) digitalWrite(iomap[1], HIGH) usleep(20) return

12. Character LCM (cont.) def setup(): sys.stdout.write(“Python YJD1602A-1 LCD Driver”) sys.stdout.write(‘\n’) pinMode(iomap[0], OUTPUT) pinMode(iomap[1], OUTPUT) pinMode(iomap[2], OUTPUT) pinMode(iomap[3], OUTPUT) pinMode(iomap[4], OUTPUT) pinMode(iomap[5], OUTPUT) sys.stdout.write(“Setting Up Screen”) sys.stdout.write(‘\n’) lcdcommand(‘0011’) #Initialization Sequence lcdcommand(‘0011’) #Initialization Sequence lcdcommand(‘0011’) #Initialization Sequence lcdcommand(‘0010’) #4BIT Mode

13. Character LCM (cont.) lcdcommand(‘00000001’) # Reset lcdcommand(‘00001100’) # Display On sys.stdout.write(“Transferring LCD Control to main loop”) sys.stdout.write(‘\n’) sys.stdout.write(“Process PID: “) sys.stdout.write(str(os.getpid())) sys.stdout.write(‘\n’)

14. Character LCM (cont.) def loop(): with open('/proc/uptime', 'r') as f: uptime_seconds = float(f.readline().split()[0]) uptime_string = str(datetime.timedelta(seconds = uptime_seconds)) pid = str(os.getpid()) lcdcommand('10000000') #upper line display lcdprint("B-Bone Uptime") lcdcommand('11000000') #lower line display lcdprint(uptime_string) usleep(1000) #1ms delay run(setup,loop)

15. Character LCM (cont.)

16. Character LCM (cont.) • Exercise: • Show your student ID and “exercise11” on each line.

17. Pin Configuration

18. END