Advice on LCD display for Picaxe project.

[HellasTechn]

Yes, sorry for that. I have updated the post with the PDF.

 

[HellasTechn]

P.S.
http://www.picaxe.com/downloads/axe133.bas.txt
Here is the code for the 18M2 to act as slave interface. I guess i could adjust it for use with the 20M2 Picaxe i already have. Then connect it with the chineese LCD i bought from e-bay. I will wire it as shown in page 5 of this PDF.
http://www.picaxe.com/docs/axe133.pdf

So far i have not been able to modify the (18m2 chip) code for use with a 20M2.

I am going to need some help on this one.

 

[CDRIVE]

Is the PE editor throwing errors? If so where?

Chris

 

[HellasTechn]

Yes.
Syntax error on line 85 at/before position 9
Error: Pin C.6 is input only

at line 36 i changed c.6 to c.1

C.1 is symbol spare1 = C.1 ; spare output 1 (line 32)

 

[HellasTechn]

Here is the code as i changed it so far

; AXE133 Serial LCD/OLED using PICAXE-18M2
; Emulates basic serial operation of the popular AXE033 module
; CPS, May 2011
; v2 18/01/2012

#picaxe 20M2

; ********************************************
; Note you must uncomment just one of these two options
; depending on whether you have an LCD or OLED module
;#define use_OLED
#define use_LCD
; ********************************************


; Supported Commands
; 0-7, 8-15 CGRAM characters
; 16-252 normal ASCII characters, according to selected character map table
; 253, X display 16 character pre-saved message from EEPROM memory, X can be 0-15
; 254, X LCD command, X can be 0 to 255
; 255, X control outputs C.2, C.1, C.0 (via lower 3 bits of X)
; So, if using a backlit LCD with the active low transistor driver
; on output C.2, then 255,%000 switches backlight on and 255,%100 switches off


#define use_welcome ; display the welcome message upon power up
symbol line_length = 16 ; change to 20 for displays with 20 character lines

symbol baud = N2400_16 ; Serial baud rate 2400,N,8,1. Note main program runs at 16MHz

symbol spare0 = C.0 ; spare output 0
symbol spare1 = C.1 ; spare output 1
symbol spare2 = C.2 ; spare output 2 (or optional backlight)
symbol backlight = C.2 ; optional backlight control for backlit LCDs, active low
symbol RX = C.5 ; serial receive pin
symbol enable = C.1 ; LCD enable
symbol rs = C.7 ; LCD RS


; LCD data pins are on B.0 to B.7

; Store the 16 character user defined messages in EEPROM data memory
; First two messages are optionally used as welcome message

; If using a display with 20 characters you will need to edit
; the start addresses to be multiples of 20 (currently at 16)
; and add 4 characters to each message.
; Please remember 4 line displays always use the strange 1-3-2-4 layout.

#ifdef use_OLED
EEPROM $00, (" Serial OLED ") ; store msg in the EEPROM memory
#else
EEPROM $00, (" Serial LCD ") ; store msg in the EEPROM memory
#endif


EEPROM $10, (" www.picaxe.com ") ; store msg in the EEPROM memory

EEPROM $20, ("This is msg 2 ") ; store msg in the EEPROM memory
EEPROM $30, ("This is msg 3 ") ; store msg in the EEPROM memory
EEPROM $40, ("This is msg 4 ") ; store msg in the EEPROM memory
EEPROM $50, ("This is msg 5 ") ; store msg in the EEPROM memory
EEPROM $60, ("This is msg 6 ") ; store msg in the EEPROM memory
EEPROM $70, ("This is msg 7 ") ; store msg in the EEPROM memory
EEPROM $80, ("This is msg 8 ") ; store msg in the EEPROM memory
EEPROM $90, ("This is msg 9 ") ; store msg in the EEPROM memory
EEPROM $A0, ("This is msg 10 ") ; store msg in the EEPROM memory
EEPROM $B0, ("This is msg 11 ") ; store msg in the EEPROM memory
EEPROM $C0, ("This is msg 12 ") ; store msg in the EEPROM memory
EEPROM $D0, ("This is msg 13 ") ; store msg in the EEPROM memory
EEPROM $E0, ("This is msg 14 ") ; store msg in the EEPROM memory
EEPROM $F0, ("This is msg 15 ") ; store msg in the EEPROM memory

;initialise LCD
init:
gosub LCD_init ; initialise LCD

; display welcome message if desired
#ifdef use_welcome
let b1 = 0 ; message 0 on top line
gosub msg ; do it

low rs ; command mode
let pinsB = 192 ; move to line 2, instruction 192
pulsout enable,1 ; pulse the enable pin to send data.
high rs ; character mode again

let b1 = 1 ; message 1 on bottom line
gosub msg ; do it
#endif

; main program loop, runs at 16MHz

main:

serin RX,baud,b1 ; wait for the next byte

; NB keep character mode test as first item in this list to optimise speed
if b1 < 253 then
let pinsB = b1 ; output the data
pulsout enable,1 ; pulse the enable pin to send data.
goto main ; quickly loop back to top
else if b1 = 254 then
low rs ; change to command mode for next character
serin RX,baud,b1 ; wait for the command byte
let pinsB = b1 ; output the data
pulsout enable,1 ; pulse the enable pin to send data.
high rs ; back to character mode
goto main ; quickly loop back to top
else if b1 = 253 then
serin RX,baud,b1 ; wait for the next byte
gosub msg ; do the 16 character message
goto main ; back to top
else ; must be 255
serin RX,baud,b1 ; wait for the next byte
let pinsC = b1 & %00000111 | %10000000
; output the data on C.0 to C.1, keep RS high
goto main ; back to top
end if


; power on LCD initialisation sub routine
LCD_init:
let dirsC = %11000111 ; PortC 0,1,2,6,7 all outputs
let dirsB = %11111111 ; PortB all outputs



#ifdef use_OLED
; Winstar OLED Module Initialisation
; according to WS0010 datasheet (8 bit mode)

pause 500 ; Power stabilistation = 500ms

; Function set - select only one of these 4 character table modes
;let pinsB = %00111000 ; 8 bit, 2 line, 5x8 , English_Japanese table
let pinsB = %00111001 ; 8 bit, 2 line, 5x8 , Western_European table1
;let pinsB = %00111010 ; 8 bit, 2 line, 5x8 , English_Russian table
;let pinsB = %00111011 ; 8 bit, 2 line, 5x8 , Western_European table2

pulsout enable,1 ;

let pinsB = %00001100 ; Display on, no cursor, no blink
pulsout enable,1

let pinsB = %00000001 ; Display Clear
pulsout enable,1
pause 7 ; Allow 6.2ms to clear display

setfreq m16 ; now change to 16Mhz

let pinsB = %00000010 ; Return Home
pulsout enable,1

let pinsB = %00000110 ; Entry Mode, ID=1, SH=0
pulsout enable, 1


#else
; Standard LCD Module Initialisation
pause 15 ; Wait 15ms for LCD to reset.

let pinsB = %00110000 ; 8 bit, 2 line
pulsout enable,1 ; Send data by pulsing enable
pause 5 ; Wait 5 ms
pulsout enable,1 ; Send data 48 again
pulsout enable,1 ; Send data 48 again

setfreq m16 ; now change to 16Mhz

let pinsB = %00111000 ; LCD - 8 bit, 2 line, 5x8
pulsout enable,1

let pinsB = %00000001 ; Clear Display
pulsout enable,1
pause 8 ; 8 = 2ms at 16MHz

let pinsB = %00000010 ; return home
pulsout enable,1

let pinsB = %00000110 ; Entry mode
pulsout enable,1
pause 1

let pinsB = %00001100 ; Display on, no cursor, no blink
pulsout enable,1
#endif

high rs ; Leave in character mode
return


; display message from EEPROM sub routine
; message number 0-15 must be in b1 when called
; uses (alters) b1, b2, b3, b4
msg:
let b2 = b1 & %00001111 * line_length
; EEPROM start address is 0 to 15 multiplied by 16
let b3 = b2 + line_length - 1 ; end address is start address + (line_length - 1)
for b4 = b2 to b3 ; for 16 times
read b4,b1 ; read next character from EEPROM data memory into b1
let pinsB = b1 ; output the data
pulsout enable,1 ; pulse the enable pin to send data.
next b4 ; next loop
return

; Check end user has defined just one type of display
#ifndef use_OLED
#ifndef use_LCD
#error "Oops - no OLED / LCD type defined at top of program!"
#endif
#endif

#ifdef use_OLED
#ifdef use_LCD
#error "Oops - both OLED / LCD types defined at top of program!"
#endif
#endif

 

[HellasTechn]

I also have some trouble understanding the connection diagram here:
http://www.picaxe.com/docs/axe133.pdf
page 5.

I understand that H3 is "spare" but H2 pin C.5 where do i connect that ?
Also what is CON1 connevted to ?

 

[HellasTechn]

C.5 on H2 must be the serin pin.

 

[CDRIVE]

Let's take one thing at a time. I changed only two lines of code and it syntax tested OK. These are lines 45 and 49.

Chris

; *******************************
; ***** Sample Header File  *****
; *******************************
;    Filename:        
;    Date:            
;    File Version:    
;    Written by:
;    Function:      
;    Last Revision:
;    Target PICAXE:  20M2
; *******************************


; AXE133 Serial LCD/OLED using PICAXE-20M2
; Emulates basic serial operation of the popular AXE033 module
; CPS, May 2011
; v2 18/01/2012

#picaxe 20M2

; ********************************************
; Note you must uncomment just one of these two options
; depending on whether you have an LCD or OLED module
;#define use_OLED
#define use_LCD
; ********************************************


; Supported Commands
; 0-7, 8-15    CGRAM characters
; 16-252    normal ASCII characters, according to selected character map table
; 253, X    display 16 character pre-saved message from EEPROM memory, X can be 0-15
; 254, X    LCD command, X can be 0 to 255
; 255, X    control outputs C.2, C.1, C.0 (via lower 3 bits of X)
;        So, if using a backlit LCD with the active low transistor driver
;        on output C.2, then 255,%000 switches backlight on and 255,%100 switches off


#define use_welcome    ; display the welcome message upon power up
symbol line_length = 16    ; change to 20 for displays with 20 character lines

symbol baud = N2400_16    ; Serial baud rate 2400,N,8,1. Note main program runs at 16MHz

symbol spare0     = C.0 ; spare output 0
symbol spare1     = C.6 ; spare output 1
symbol spare2     = C.2 ; spare output 2 (or optional backlight)
symbol backlight     = C.2 ; optional backlight control for backlit LCDs, active low
symbol RX        = C.5    ; serial receive pin
symbol enable     = C.1    ; LCD enable
symbol rs         = C.7    ; LCD RS


; LCD data pins are on B.0 to B.7

; Store the 16 character user defined messages in EEPROM data memory
; First two messages are optionally used as welcome message

; If using a display with 20 characters you will need to edit
; the start addresses to be multiples of 20 (currently at 16)
; and add 4 characters to each message.
; Please remember 4 line displays always use the strange 1-3-2-4 layout.

#ifdef use_OLED      
EEPROM $00, ("  Serial OLED   ")     ; store msg in the EEPROM memory
#else
EEPROM $00, ("   Serial LCD   ")     ; store msg in the EEPROM memory
#endif


EEPROM $10, (" www.picaxe.com ")     ; store msg in the EEPROM memory

EEPROM $20, ("This is msg 2   ")     ; store msg in the EEPROM memory
EEPROM $30, ("This is msg 3   ")     ; store msg in the EEPROM memory
EEPROM $40, ("This is msg 4   ")     ; store msg in the EEPROM memory
EEPROM $50, ("This is msg 5   ")     ; store msg in the EEPROM memory
EEPROM $60, ("This is msg 6   ")     ; store msg in the EEPROM memory
EEPROM $70, ("This is msg 7   ")     ; store msg in the EEPROM memory
EEPROM $80, ("This is msg 8   ")     ; store msg in the EEPROM memory
EEPROM $90, ("This is msg 9   ")     ; store msg in the EEPROM memory
EEPROM $A0, ("This is msg 10  ")     ; store msg in the EEPROM memory
EEPROM $B0, ("This is msg 11  ")     ; store msg in the EEPROM memory
EEPROM $C0, ("This is msg 12  ")     ; store msg in the EEPROM memory
EEPROM $D0, ("This is msg 13  ")     ; store msg in the EEPROM memory
EEPROM $E0, ("This is msg 14  ")     ; store msg in the EEPROM memory
EEPROM $F0, ("This is msg 15  ")     ; store msg in the EEPROM memory

;initialise LCD
init:
    gosub LCD_init         ; initialise LCD

; display welcome message if desired
#ifdef use_welcome  
    let b1 = 0            ; message 0 on top line
    gosub msg            ; do it

    low rs            ; command mode
    let pinsB = 192        ; move to line 2, instruction 192
    pulsout enable,1      ; pulse the enable pin to send data.
    high rs            ; character mode again
  
    let b1 = 1            ; message 1 on bottom line
    gosub msg            ; do it
#endif      
      
; main program loop, runs at 16MHz

main:

    serin RX,baud,b1            ; wait for the next byte

    ; NB keep character mode test as first item in this list to optimise speed
    if b1 < 253 then
        let pinsB = b1         ; output the data
        pulsout enable,1      ; pulse the enable pin to send data.
        goto main            ; quickly loop back to top
    else if b1 = 254 then
        low rs                  ; change to command mode for next character
        serin RX,baud,b1        ; wait for the command byte
        let pinsB = b1         ; output the data
        pulsout enable,1      ; pulse the enable pin to send data.
        high rs            ; back to character mode
        goto main            ; quickly loop back to top
    else if b1 = 253 then
        serin RX,baud,b1        ; wait for the next byte
        gosub msg            ; do the 16 character message
        goto main            ; back to top
    else ; must be 255
        serin RX,baud,b1        ; wait for the next byte
        let pinsC = b1 & %00000111 | %10000000
                        ; output the data on C.0 to C.1, keep RS high
        goto main            ; back to top
    end if


; power on LCD initialisation sub routine
LCD_init:
    let dirsC = %11000111    ; PortC 0,1,2,6,7 all outputs
    let dirsB = %11111111    ; PortB all outputs
  

  
#ifdef use_OLED
    ; Winstar OLED Module Initialisation
    ; according to WS0010 datasheet (8 bit mode)

    pause 500             ; Power stabilistation = 500ms

    ; Function set - select only one of these 4 character table modes
    ;let pinsB = %00111000     ; 8 bit, 2 line, 5x8 , English_Japanese table
    let pinsB = %00111001     ; 8 bit, 2 line, 5x8 , Western_European table1
    ;let pinsB = %00111010     ; 8 bit, 2 line, 5x8 , English_Russian  table
    ;let pinsB = %00111011     ; 8 bit, 2 line, 5x8 , Western_European table2
  
    pulsout enable,1      ;
      
    let pinsB = %00001100    ; Display on, no cursor, no blink
    pulsout enable,1    

    let pinsB = %00000001     ; Display Clear
    pulsout enable,1
    pause 7            ; Allow 6.2ms to clear display

    setfreq m16            ; now change to 16Mhz

    let pinsB = %00000010     ; Return Home
    pulsout enable,1

    let pinsB = %00000110     ; Entry Mode, ID=1, SH=0
    pulsout enable, 1


#else  
    ; Standard LCD Module Initialisation
    pause 15             ; Wait 15ms for LCD to reset.

    let pinsB = %00110000     ; 8 bit, 2 line
    pulsout enable,1      ; Send data by pulsing enable
    pause 5             ; Wait 5 ms
    pulsout enable,1          ; Send data 48 again
    pulsout enable,1      ; Send data 48 again
  
    setfreq m16            ; now change to 16Mhz

    let pinsB = %00111000     ; LCD  - 8 bit, 2 line, 5x8
    pulsout enable,1
          
    let pinsB = %00000001    ; Clear Display
    pulsout enable,1    
    pause 8            ; 8 = 2ms at 16MHz
  
    let pinsB = %00000010     ; return home
    pulsout enable,1

    let pinsB = %00000110    ; Entry mode
    pulsout enable,1    
    pause 1          

    let pinsB = %00001100    ; Display on, no cursor, no blink
    pulsout enable,1    
#endif
  
    high rs            ; Leave in character mode
    return


; display message from EEPROM sub routine
; message number 0-15 must be in b1 when called
; uses (alters) b1, b2, b3, b4
msg:
    let b2 = b1 & %00001111 * line_length
                        ; EEPROM start address is 0 to 15 multiplied by 16
    let b3 = b2 + line_length - 1 ; end address is start address + (line_length - 1)
    for b4 = b2 to b3            ; for 16 times
        read b4,b1            ; read next character from EEPROM data memory into b1
        let pinsB = b1         ; output the data
        pulsout enable,1      ; pulse the enable pin to send data.
    next b4                ; next loop
    return
  
; Check end user has defined just one type of display
#ifndef use_OLED
#ifndef use_LCD
#error "Oops - no OLED / LCD type defined at top of program!"
#endif
#endif

#ifdef use_OLED
#ifdef use_LCD
#error "Oops - both OLED / LCD types defined at top of program!"
#endif
#endif

 

[HellasTechn]

Ok. I understand your changes. Thankyou for that.
I will now breadboard it and see...

I guess i will leave CON1 unconnected. C.5 is serin pin, all the other are clear i think.

 

[CDRIVE]

Ok. I understand your changes. Thankyou for that.
I will now breadboard it and see...

I guess i will leave CON1 unconnected. C.5 is serin pin, all the other are clear i think.

Admittedly I didn't examine and scrutinize the entire app. I settled for acceptance in the syntax check.

Chris

 

[HellasTechn]

Same here

Software simulation is not easy to understand if you have not builded the code yourself.
I have the breadboard ready for the test. i will report back as soon as i am done.

 

[CDRIVE]

I just whisked off an email to my contact at DesignSoft that makes my favorite schematic capture/spice simulator TINA. I love Picaxe but TINA doesn't support them. This forces me to use PicaxeVSM, which is not a Picaxe product. It's a scaled down version of PROTEUS/ISIS. It's a clunky app which I hate using. If TINA supported Picaxe I would have drawn and simulated your circuit using a 20M2 and LCD already.

Chris

 

[HellasTechn]

I understand... Thank you anyway !

My first attempt failed. I used the 20m2 with the code as you mdified it and without a master picaxe to send data. I wired the 20m2 and the lcd module according to the diagram and nothing happened (no backlight on).


On the lcd there are two pins marked A and K for anode and cathode of the LED backlight. I am not sure how to connect them because the diagram is for the OLED module. That explains why backlight was off.
After going through the code i noticed that pin C.2 is reserved for enableing backlight "active low signal" but still i am not sure where to connect C.2 to.

 

[HellasTechn]

I am going to need a transistor driver for the led since the one that came with the display unit was mounted on the I2C interface board which i removed. So VCC needs to be fed to A and a PNP transistor with collector to K, emmiter to GND and base through 1k resistor to base.

 

[CDRIVE]

I am going to need a transistor driver for the led since the one that came with the display unit was mounted on the I2C interface board which i removed. So VCC needs to be fed to A and a PNP transistor with collector to K, emmiter to GND and base through 1k resistor to base.

Not quite like that. If you're using a PNP that turns on when the Picaxe pin goes low you want the Emitter connected to "K" and the Collector connected to GND. Don't forget a 1KΩ between the picaxe pin and the transistor Base.

Chris

 

[CDRIVE]

Hey, just had a thought! Why mess with PNPs when you can just invert the code by making C.2 normally low and bringing it high to turn on a NPN? In this case the Collector will be connected to "K" and Emitter connected to GND. A 1K base resistor still applies.

Chris

 

[HellasTechn]

It is just easyer to use a NPN than alter the code. I currently use a bc558 and backlight works, Well kind of, C.2 is pulsing hi - low and i dont know why. I hope i have not burned C.2 because i forgot to add the 1k resistor to transistor's base...

 

[HellasTechn]

Ok now that i dont get. C.2 only pulses from 0V to 1.5V when i connect it with the BC558 base.

 

[HellasTechn]

Not quite like that. If you're using a PNP that turns on when the Picaxe pin goes low you want the Emitter connected to "K" and the Collector connected to GND.

Why is that ?

 

[HellasTechn]

Check this out, it is the diagram of the LCD I2C module as i bought it :