Jason White wrote:
> Problem: When I run it the LCD stays blank (backlight and everything else
> turns on so its not a power issue) I've tried many diffrent code examples
> and still got nothing ...

1) Your "delay_ms" routine doesn't delay anywhere near (1ms * value). 
It's more like (10us * value), meaning your delay_ms(100) startup delay 
is actually delaying about 1ms.

2)   config at 0x2007 __CONFIG =   _HS_OSC   // internal 
high speed OSC						& _IESO_OFF  // no need for external OSC
_HS_OSC is for an external high-speed (>=4MHz) oscillator crystal. You 
want one of the _INTRC_* osc settings, then you'll need to write to 
OSCCON to bring the core clock speed up to 4MHz (IIRC it defaults to 
32kHz). Or leave it at 32kHz and your delays will be more or less right...

3)  & _PWRTE_ON // no power up timer
That turns the power up timer on. It's a good idea to use it, but maybe 
not what you were intending to do.

4) & _MCLRE_OFF // use external reset ?
Set this to _MCLRE_ON or you might have problems reprogramming the chip.
Also pull MCLR to Vcc through a 10k to 100k resistor.

5) #define ENABLE              EN=1;EN=0;
Ugh. You're raising the pin in one instruction, then lowering it 
immediately afterwards. The HD44780 isn't quick enough to pick up a 
1us-wide EN pulse. You need a minimum of (IIRC) 4us.

> you would notice the difference on the LCD even without a pot on the
> contrast (V0) right ?

Not necessarily. Low-voltage LCDs will usually work fine with the 
contrast pin grounded, though some larger displays (typically 20x2 and 
larger) need a negative voltage contrast supply (around -5V) and a pot 
to set the contrast. You can get this supply with a MAX660 or ICL7660 
voltage converter, or a diode-capacitor voltage inverter tied to your 
PIC's PWM output (which then means you gain digital control of the 
contrast by varying the duty cycle).

-- 
Phil.
piclist@philpem.me.uk
http://www.philpem.me.uk/
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