18f26k20 @ 64mhz

[cobra1]

Does anyone know how to do this?

i read that you can set the internal oscilator to 16mhz, (osccon=0x70;) then enable the PLL to multiply by 4 giving 64mhz, (pllen=1;)

i can get it to work with 16mhz internal osc, but when i try and turn on the PLL it stops working.
In the config i have it set to INTRC port on RA6, if i try HS-PLL it doesnt work.


Any ideas

[cobra1]

Ok, after many hours of playing i have got it running at 64mhz

Problem is now the LCD im using (nokia LCD) wont work. it doesnt want to display anything.

Can the LCD be used at this speed? i am trying to get a faster refresh rate on the LCD.

[Benj]

Hello,

I think that display it bit banged so you could try doing one of the following things.

Using the custom code feature go into the defines code section and edit this line of code.

#define MX_GFXLCD_PORT %a //portc I/O port

change to

#define MX_GFXLCD_PORT latx //portc I/O port

where x is the port letter you are using eg. lata for port a.

Try this and if this is still not working for you then you may have to try adding delays in the sendbyte function.

Here is the section that transmits the data to the display.

Code: Select all

#if MX_GFXLCD_TYPE == 0									//EB043 ONLY
		char i;
		clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_CS);              //MX_GFXLCD_CS 0 start of sequence
		clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);            //Clock 0
		if (Command == MX_GFXLCD_CMD)
			clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);       //0 = MX_GFXLCD_CMD
		else
			set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);         //1 = MX_GFXLCD_PARAMeter
		set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);
		for (i=0;i<8;i++)
		{
			clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);        //Clock 0
			if (Lcdout & 0x80)
				set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);     //Output MSB
			else
				clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);
			set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);          //Clock 1
			Lcdout = Lcdout << 1;                             //Shift Data to left
		}
		set_bit(MX_GFXLCD_PORT, MX_GFXLCD_CS);                //MX_GFXLCD_CS to 1 at end of sequence
	#endif

try changing to

Code: Select all

#if MX_GFXLCD_TYPE == 0									//EB043 ONLY
		char i;
		clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_CS);              //MX_GFXLCD_CS 0 start of sequence
		clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);            //Clock 0
		if (Command == MX_GFXLCD_CMD)
			clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);       //0 = MX_GFXLCD_CMD
		else
			set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);         //1 = MX_GFXLCD_PARAMeter
		set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);
		for (i=0;i<8;i++)
		{
			clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);        //Clock 0
 			delay_us(1);                  ///////////////////////////////////////////////delay added here
			if (Lcdout & 0x80)
				set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);     //Output MSB
			else
				clear_bit(MX_GFXLCD_PORT, MX_GFXLCD_SDATA);
 			delay_us(1);                  ///////////////////////////////////////////////delay added here     
			set_bit(MX_GFXLCD_PORT, MX_GFXLCD_SCLK);          //Clock 1
 			delay_us(1);                   ///////////////////////////////////////////////delay added here    
			Lcdout = Lcdout << 1;                             //Shift Data to left
		}
		set_bit(MX_GFXLCD_PORT, MX_GFXLCD_CS);                //MX_GFXLCD_CS to 1 at end of sequence
	#endif

[cobra1]

Hi Ben

Thanks for your help, that appears to have allowed the screen to work again, but even at this speed its still slow at refreshing, when creating a full screen box, you can see it as it renders the screen, scrolling down. Is there any way to speed this up more?

[cobra1]

ok, so i removed the delays you added out of curiosity to see if these were slowing down the data transfer, when removed the LCD updates at a good speed, not as fast as i would like but close enough.