Raspberry PI B - Model V2 - problems with LCD 20X - Raspberry Pi Forums

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hello,

i've connected 20x4 lcd shield on raspberry pi b - model v2, characters strange displays them, shown in link:
http://www.robofun.ro/forum/download/fi ... &mode=view

lcd shield is:
http://www.robofun.ro/lcd/shield-lcd-raspberry-pi-20x4

use os: raspbian, debian wheezy, python language , code is:

code: select all

    import rpi.gpio gpio     import time       lcd_rs = 25     lcd_e  = 24     lcd_d4 = 23     lcd_d5 = 17     lcd_d6 = 18     lcd_d7 = 22     led_on = 15       lcd_width = 20        lcd_chr = true     lcd_cmd = false      lcd_line_1 = 0x80     lcd_line_2 = 0xc0     lcd_line_3 = 0x94     lcd_line_4 = 0xd4       e_pulse = 0.00005     e_delay = 0.00005      def main():         gpio.setmode(gpio.bcm)              gpio.setup(lcd_e, gpio.out)        gpio.setup(lcd_rs, gpio.out)       gpio.setup(lcd_d4, gpio.out)       gpio.setup(lcd_d5, gpio.out)       gpio.setup(lcd_d6, gpio.out)       gpio.setup(lcd_d7, gpio.out)       gpio.setup(led_on, gpio.out)         lcd_init()        lcd_byte(lcd_line_1, lcd_cmd)       lcd_string("robofun.ro",2)       lcd_byte(lcd_line_2, lcd_cmd)       lcd_string("raspberry pi",2)       lcd_byte(lcd_line_3, lcd_cmd)       lcd_string("lcd", 2)       lcd_byte(lcd_line_4, lcd_cmd)       lcd_string("20x4", 2)       def lcd_init():       lcd_byte(0x33,lcd_cmd)       lcd_byte(0x32,lcd_cmd)       lcd_byte(0x28,lcd_cmd)       lcd_byte(0x0c,lcd_cmd)        lcd_byte(0x06,lcd_cmd)       lcd_byte(0x01,lcd_cmd)       def lcd_string(message,style):       # style=1 left justified       # style=2 centred       # style=3 right justified        if style==1:         message = message.ljust(lcd_width," ")        elif style==2:         message = message.center(lcd_width," ")       elif style==3:         message = message.rjust(lcd_width," ")        in range(lcd_width):         lcd_byte(ord(message[i]),lcd_chr)      def lcd_byte(bits, mode):       # send byte data pins       # bits = data       # mode = true  character       #        false command        gpio.output(lcd_rs, mode) # rs        # high bits       gpio.output(lcd_d4, false)       gpio.output(lcd_d5, false)       gpio.output(lcd_d6, false)       gpio.output(lcd_d7, false)       if bits&0x10==0x10:         gpio.output(lcd_d4, true)       if bits&0x20==0x20:         gpio.output(lcd_d5, true)       if bits&0x40==0x40:         gpio.output(lcd_d6, true)       if bits&0x80==0x80:         gpio.output(lcd_d7, true)        # toggle 'enable' pin       time.sleep(e_delay)          gpio.output(lcd_e, true)        time.sleep(e_pulse)       gpio.output(lcd_e, false)        time.sleep(e_delay)             # low bits       gpio.output(lcd_d4, false)       gpio.output(lcd_d5, false)       gpio.output(lcd_d6, false)       gpio.output(lcd_d7, false)       if bits&0x01==0x01:         gpio.output(lcd_d4, true)       if bits&0x02==0x02:         gpio.output(lcd_d5, true)       if bits&0x04==0x04:         gpio.output(lcd_d6, true)       if bits&0x08==0x08:         gpio.output(lcd_d7, true)        # toggle 'enable' pin       time.sleep(e_delay)          gpio.output(lcd_e, true)        time.sleep(e_pulse)       gpio.output(lcd_e, false)        time.sleep(e_delay)         if __name__ == '__main__':       main()

mariusionescu wrote:hello,
i've connected 20x4 lcd shield on raspberry pi b - model v2, characters strange displays them, shown in link:
http://www.robofun.ro/forum/download/fi ... &mode=view
lcd shield is:
http://www.robofun.ro/lcd/shield-lcd-raspberry-pi-20x4
use os: raspbian, debian wheezy, python language , code is:

code: select all

    import rpi.gpio gpio     import time     lcd_rs = 25     lcd_e  = 24     lcd_d4 = 23     lcd_d5 = 17     lcd_d6 = 18     lcd_d7 = 22     led_on = 15     lcd_width = 20        lcd_chr = true     lcd_cmd = false     lcd_line_1 = 0x80     lcd_line_2 = 0xc0     lcd_line_3 = 0x94     lcd_line_4 = 0xd4     e_pulse = 0.00005     e_delay = 0.00005     def main():       gpio.setmode(gpio.bcm)              gpio.setup(lcd_e, gpio.out)        gpio.setup(lcd_rs, gpio.out)       gpio.setup(lcd_d4, gpio.out)       gpio.setup(lcd_d5, gpio.out)       gpio.setup(lcd_d6, gpio.out)       gpio.setup(lcd_d7, gpio.out)       gpio.setup(led_on, gpio.out)       lcd_init()       lcd_byte(lcd_line_1, lcd_cmd)       lcd_string("robofun.ro",2)       lcd_byte(lcd_line_2, lcd_cmd)       lcd_string("raspberry pi",2)       lcd_byte(lcd_line_3, lcd_cmd)       lcd_string("lcd", 2)       lcd_byte(lcd_line_4, lcd_cmd)       lcd_string("20x4", 2)     def lcd_init():       lcd_byte(0x33,lcd_cmd)       lcd_byte(0x32,lcd_cmd)       lcd_byte(0x28,lcd_cmd)       lcd_byte(0x0c,lcd_cmd)        lcd_byte(0x06,lcd_cmd)       lcd_byte(0x01,lcd_cmd)      def lcd_string(message,style):       # style=1 left justified       # style=2 centred       # style=3 right justified       if style==1:         message = message.ljust(lcd_width," ")        elif style==2:         message = message.center(lcd_width," ")       elif style==3:         message = message.rjust(lcd_width," ")       in range(lcd_width):         lcd_byte(ord(message[i]),lcd_chr)     def lcd_byte(bits, mode):       # send byte data pins       # bits = data       # mode = true  character       #        false command       gpio.output(lcd_rs, mode) # rs       # high bits       gpio.output(lcd_d4, false)       gpio.output(lcd_d5, false)       gpio.output(lcd_d6, false)       gpio.output(lcd_d7, false)       if bits&0x10==0x10:         gpio.output(lcd_d4, true)       if bits&0x20==0x20:         gpio.output(lcd_d5, true)       if bits&0x40==0x40:         gpio.output(lcd_d6, true)       if bits&0x80==0x80:         gpio.output(lcd_d7, true)       # toggle 'enable' pin       time.sleep(e_delay)          gpio.output(lcd_e, true)        time.sleep(e_pulse)       gpio.output(lcd_e, false)        time.sleep(e_delay)            # low bits       gpio.output(lcd_d4, false)       gpio.output(lcd_d5, false)       gpio.output(lcd_d6, false)       gpio.output(lcd_d7, false)       if bits&0x01==0x01:         gpio.output(lcd_d4, true)       if bits&0x02==0x02:         gpio.output(lcd_d5, true)       if bits&0x04==0x04:         gpio.output(lcd_d6, true)       if bits&0x08==0x08:         gpio.output(lcd_d7, true)       # toggle 'enable' pin       time.sleep(e_delay)          gpio.output(lcd_e, true)        time.sleep(e_pulse)       gpio.output(lcd_e, false)        time.sleep(e_delay)        if __name__ == '__main__':       main()
given appear using "4-bit" interface suspect it's timing issue** - values of e_pulse , e_delay (in us) , how e_pulse value compare values various 4-bit methods shown here?****:
http://www.cpmspectrepi.webspace.virgin ... gdata.html
, here:
http://www.raspberrypi.org/forums/viewt ... 44&t=91735
trev.
** similar shown here?:
http://www.cpmspectrepi.webspace.virgin ... ml#testing_...
**** full circuit details can found elsewhere within webpages


raspberrypi



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