A quick followup now that the display is working. The problem seems to have been with the display memory access after all. The IO pins were correctly configured but the DMA controller was hanging while reading from SDRAM. With no fresh pixel data feeding the LCD controller all LCD signaling stopped.

It looks like the cause was a bad solder joint on one of the SDRAM address or data pins.

Chip, thanks again for your help!

Zach

--- In l..., "zeveland" wrote:
> Hi, I have been working to modify the LCD demo for the IAR LPC2478-STK board to a custom board with its own TFT. The new TFT uses DE-mode signaling and the example uses SYNC-mode so I have been porting things over and have run into a strange IO issue.
>
> My problem is the reverse of problems others have reported with modifying the LCD example - I see activity on the data lines but nothing on the control lines. LCDDCLK pulls high, LCDPWR pulls low, etc. Even setting the appropriate PINSEL bits to 00 has no effect - after setting a pin as GPIO I'm not able to affect its state with writes to the CLR or SET registers. This problem is on PORT2, using fast IO operations.
>
> I'm new to LPC2000 development - what would cause a pin to not behave as a GPIO when instructed to by a write to PINSEL?
>
> Also, does anyone have general words of advice on DE-mode operation with the LPC2478's built-in LCD controller?
>
> Thanks,
> Zach
>

Start a New Thread

I'm not sure about that. I have 'played with' DE and SYNC modes on panels from BeyondTek, NEC and Hitachi and the only changes I have made was to LCDENAB, VSYNC (LCDFP), and HSYNC (LCDLP) only. I use a simple #define to switch between the two modes without any other changes.

Hwoever, some panels do require that the pins be held low for example hold SYNC pins low when using DE mode.

Chip

--- In l..., Zach Eveland wrote:
>
> Chip, thank you for the advice and, yes; PINSEL is already connecting all
> pins to the LCD block.
>
> I tried the same code on the original dev board where it seems to work fine.
> At least part of the problem seems to stem from the SDRAM. On enabling the
> SDRAM test on startup and stepping through the 32-bit verification test, the
> dev board passes all tests and the new board fails part of the way through.
>
> I am adjusting timing and other SDRAM parameters for the new board but is it
> possible that a misconfiguration of the SDRAM would prevent normal LCD
> control signal use (possibly by interfering with the operation of the MAM)?
>
> Thanks again for your help.
>
> Best,
> Zach
>
> On Fri, Aug 6, 2010 at 12:43 PM, Chip wrote:
>
> >
> >
> > DE mode uses LCDENAB while "SYNC" mode uses "HS" and "VS" (LCDLP and
> > LCDFP).
> >
> > Are your pin selects enabling all three of these controls to work as LCD
> > function?
> >
> > Chip
> >
> >
> > --- In l... , "zeveland"
> > wrote:
> > >
> > >
> > > Hi, I have been working to modify the LCD demo for the IAR LPC2478-STK
> > board to a custom board with its own TFT. The new TFT uses DE-mode signaling
> > and the example uses SYNC-mode so I have been porting things over and have
> > run into a strange IO issue.
> > >
> > > My problem is the reverse of problems others have reported with modifying
> > the LCD example - I see activity on the data lines but nothing on the
> > control lines. LCDDCLK pulls high, LCDPWR pulls low, etc. Even setting the
> > appropriate PINSEL bits to 00 has no effect - after setting a pin as GPIO
> > I'm not able to affect its state with writes to the CLR or SET registers.
> > This problem is on PORT2, using fast IO operations.
> > >
> > > I'm new to LPC2000 development - what would cause a pin to not behave as
> > a GPIO when instructed to by a write to PINSEL?
> > >
> > > Also, does anyone have general words of advice on DE-mode operation with
> > the LPC2478's built-in LCD controller?
> > >
> > > Thanks,
> > > Zach
> > >
> >
> >
>

Start a New Thread

Chip, thank you for the advice and, yes; PINSEL is already connecting all
pins to the LCD block.

I tried the same code on the original dev board where it seems to work fine.
At least part of the problem seems to stem from the SDRAM. On enabling the
SDRAM test on startup and stepping through the 32-bit verification test, the
dev board passes all tests and the new board fails part of the way through.

I am adjusting timing and other SDRAM parameters for the new board but is it
possible that a misconfiguration of the SDRAM would prevent normal LCD
control signal use (possibly by interfering with the operation of the MAM)?

Thanks again for your help.

Best,
Zach

On Fri, Aug 6, 2010 at 12:43 PM, Chip wrote:

> DE mode uses LCDENAB while "SYNC" mode uses "HS" and "VS" (LCDLP and
> LCDFP).
>
> Are your pin selects enabling all three of these controls to work as LCD
> function?
>
> Chip
> --- In l... , "zeveland"
> wrote:
> >
> >
> > Hi, I have been working to modify the LCD demo for the IAR LPC2478-STK
> board to a custom board with its own TFT. The new TFT uses DE-mode signaling
> and the example uses SYNC-mode so I have been porting things over and have
> run into a strange IO issue.
> >
> > My problem is the reverse of problems others have reported with modifying
> the LCD example - I see activity on the data lines but nothing on the
> control lines. LCDDCLK pulls high, LCDPWR pulls low, etc. Even setting the
> appropriate PINSEL bits to 00 has no effect - after setting a pin as GPIO
> I'm not able to affect its state with writes to the CLR or SET registers.
> This problem is on PORT2, using fast IO operations.
> >
> > I'm new to LPC2000 development - what would cause a pin to not behave as
> a GPIO when instructed to by a write to PINSEL?
> >
> > Also, does anyone have general words of advice on DE-mode operation with
> the LPC2478's built-in LCD controller?
> >
> > Thanks,
> > Zach
> >
> Start a New Thread

DE mode uses LCDENAB while "SYNC" mode uses "HS" and "VS" (LCDLP and LCDFP).

Are your pin selects enabling all three of these controls to work as LCD function?

Chip

--- In l..., "zeveland" wrote:
> Hi, I have been working to modify the LCD demo for the IAR LPC2478-STK board to a custom board with its own TFT. The new TFT uses DE-mode signaling and the example uses SYNC-mode so I have been porting things over and have run into a strange IO issue.
>
> My problem is the reverse of problems others have reported with modifying the LCD example - I see activity on the data lines but nothing on the control lines. LCDDCLK pulls high, LCDPWR pulls low, etc. Even setting the appropriate PINSEL bits to 00 has no effect - after setting a pin as GPIO I'm not able to affect its state with writes to the CLR or SET registers. This problem is on PORT2, using fast IO operations.
>
> I'm new to LPC2000 development - what would cause a pin to not behave as a GPIO when instructed to by a write to PINSEL?
>
> Also, does anyone have general words of advice on DE-mode operation with the LPC2478's built-in LCD controller?
>
> Thanks,
> Zach
>

Start a New Thread

Hi, I have been working to modify the LCD demo for the IAR LPC2478-STK board to a custom board with its own TFT. The new TFT uses DE-mode signaling and the example uses SYNC-mode so I have been porting things over and have run into a strange IO issue.

My problem is the reverse of problems others have reported with modifying the LCD example - I see activity on the data lines but nothing on the control lines. LCDDCLK pulls high, LCDPWR pulls low, etc. Even setting the appropriate PINSEL bits to 00 has no effect - after setting a pin as GPIO I'm not able to affect its state with writes to the CLR or SET registers. This problem is on PORT2, using fast IO operations.

I'm new to LPC2000 development - what would cause a pin to not behave as a GPIO when instructed to by a write to PINSEL?

Also, does anyone have general words of advice on DE-mode operation with the LPC2478's built-in LCD controller?

Thanks,
Zach

Start a New Thread