migration from 16F876a to 18F25k22

[MOUNTAIN747]

Thanks Robert for your comments. Yep, I've looked at evey piece of document I can find and the microelektronika schematic is the only thing I can find to give me any idea of what to do with Vo, and of course they are not using the same GLCD so its just a roll of the dice and hope for the best.

The attatched datasheet shows the Negative Voltage Generator at the bottom right of the page. notice V0 is an input to the NVG. So, Robert, do you think V0 is a Ground reference for the NVG. If we look at the easypic_v7 data sheet, microelektronika takes Vo to a 10k pot to the NVG, which of course will bring Vo bellow Vss. I think I will start with the 10k pot to ground and if the contrast is not great enough I tie the pot to NVG. I will use your advise on how to handle the LED's. Are you using only a 15 ohm resistor on LEDA?

CN2 GLCD uses 20 pin FFC cable
Pin function description My Action
1. VSS GND GND
2. VDD Logic Power input +5V
3. VO LCD contrast control POT 4kohm
4. AO Command / Data Select U1.RA.7
5. /WR 8080: Data Write U1.RC.0
6. /RD 8080: Data Read U1.RC.1
7. DO Data buss line0 U1.RD.0
8. D1 Data buss line1 U1.RD.1
9. D2 Data buss line2 U1.RD.2
10. D3 Data buss ilne3 U1.RD.3
11. D4 Data buss line4 U1.RD.4
12. D5 Data buss line5 U1.RD.5
13. D6 Data buss line6 U1.RD.6
14. D7 Data buss line7 U1.RD.7
15. /CS LCD Controller function Reset U1.RC.3
17. VEE Negative voltage output (-23V) ???
18. SEL1 SEL1=L, 8080 interface; GND
19. FGND Front Panel Ground GND
20. NC

CN3 LED wiring
21. LEDA Power for led Backlight(A) POT_500 ohm to Vcc
22. LEDK Power for led Backlight(K) GND

Thanks Again Robert!
Wayne

[Demon]

I have 100R and 1K pots on my circuit; backlight and contrast (can't say which has which pot by looking at it).


Look at the Electronic Parameters at bottom left:
Voltage Logic 5V typ.
Voltage LCD 20V typ.

The LCD has a range of 4.5 to 30 volts, 5 volts should work, and I'd stay away from the upper max. I'd start with an old PC power supply (5V and 12V) and give that a shot if you don't have a variable power supply, or a bunch of old wall adapters.

So yeah, I'd go with 500R pot on LEDA and 10K pot on V0 to start, and then tweak until I hit a pot that has an acceptable range. You'll see a sweet spot when you get to the right one; from dark to not "too" bright. Brighter LEDs mean shorter life, I aim for the just-enough-for-me range.


I also noticed something else on your datasheet; CONTROLLER: RA8835 OR EQUAL. I'd do some googling on RA8835 and see if more examples come up. You can never have too many schematics, tables or descriptions.

Robert

[MOUNTAIN747]

Thanks Robert, I'll let you know how it turns out!

[Demon]

I used the 16F628 and 16F877 before but it looks like I'll have to move up the food chain and the 18F2xK22 and 18F4xK22 series look like just what I need. At least I'm not forced to upgrade to PBP 3.0 yet:

http://melabs.com/support/patches.htm#pbp

PBP 2.60A:
Adds support for: PIC12F1822, 12LF1822, 16F1823, 16LF1823, 12F617, 16F722A, 16F723A, 16LF722A, 16LF723A, 18F23K22, 18F24K22, 18F25K22, 18F26K22, 18F43K22, 18F44K22, 18F45K22, 18F46K22, 18LF23K22, 18LF24K22, 18LF25K22, 18LF26K22, 18LF43K22, 18LF44K22, 18LF45K22, 18LF46K22

And I can even use the low voltage versions if I want. WOOT!

Robert

[MOUNTAIN747]

I used the 16F628 and 16F877 before but it looks like I'll have to move up the food chain and the 18F2xK22 and 18F4xK22 series look like just what I need. At least I'm not forced to upgrade to PBP 3.0 yet:

http://melabs.com/support/patches.htm#pbp



And I can even use the low voltage versions if I want. WOOT!

Robert



Robert

Robert, I've got my GLCD working with very little modification to your code. I'm using an 18F45K22. I still have a few bugs to work out with the GLCD code but at least I have something on the screen. The migration to 18F was not too difficult with the exception of a problem I had with ports. my first setup was the same as if I was using 16F and the ports did not work. I then set up ports like this:

asm
;PortA setup
MOVLB 0Fh
CLRF PORTA
CLRF ANSELA
MOVLW 30h ;PortA <5:4> input - Navigator
MOVWF TRISA
;PortB setup
MOVLB 0Fh
CLRF PORTB
CLRF ANSELB
MOVLW 03h ;PortB <1:0> input - Navigator
MOVWF TRISB
;PortC setup
MOVLB 0Fh
CLRF PORTC
CLRF ANSELC
CLRF TRISC
;PortD setup
MOVLB 0Fh
CLRF PORTD
CLRF ANSELD
CLRF TRISD
;PortE setup
MOVLB 0Fh
CLRF PORTE
CLRF ANSELE
MOVLW 0Fh ;PortE <2:0> input - Navigator
MOVWF TRISE
ENDASM

and all works well. I haven't had time to look at Darrel's 'All digital' to see how he handled 18F series but it may be easer to use his include rutine.

Wayne

[Demon]

...
17. VEE Negative voltage output (-23V) ???
...

Wayne,

I've been thinking of the negative voltage that your LCD would like to have. You might be getting acceptable results using 5VDC+, but if you're not satisfied with the brightness/contrast, I totally forgot that you can have -12VDC on a PC PSU. That's still safely within the operating specs of the LCD.

http://pcsupport.about.com/od/inside...in-12v-psu.htm

Robert