Hello,
I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8 bits
colors).
Now I've got a new project with same LPC2478 but for cost reason we would
like to use the internal RAM for the LCD :
We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
The idea is to use 4 bit / pixel (it's enough for this product).
I keep the same project changing only the LCD parameters (width , height pulse
width ....) and the memory adress (0xA0000000 for sdram and 0x40000000 for
64kbyte internal sram.
For variables... I use 16kb sram at adress 0x7FE00000.
The LPC2478 is running (I send mesage on UART with success) but I've got
strange display :
It seems to be an automatic mode who alternate full screen red, green, blue,
white, black, big cross pattern, small cross pattern and horizontal lines (black
& white)). Every two seconds it change the color and this cycle is infinite.
I've the same displays on 4.3" and 7 inch displays.
Does someone has experience to drive an LCD directly from internal SRAM and has
an idea about these test screens ?
Thanks,
Sebastien
LPC2478 LCD controller on internal RAM
Started by ●October 23, 2012
Reply by ●October 23, 20122012-10-23
Hi,
> I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8
> bits colors).
> Now I've got a new project with same LPC2478 but for cost reason we would
> like to use the internal RAM for the LCD :
>
> We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
> The idea is to use 4 bit / pixel (it's enough for this product).
>
> I keep the same project changing only the LCD parameters (width , height
> pulse width ....) and the memory adress (0xA0000000 for sdram and
> 0x40000000 for 64kbyte internal sram.
>
> For variables... I use 16kb sram at adress 0x7FE00000.
I do not believe the LCD controller has AHB or APB access to the 64K SRAM of
the CPU. Datasheet section 7.3 indicates the 64K of RAM is for exclusive
use by the CPU.
Regards,
--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
SolderCore Development Platform http://www.soldercore.com
> I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8
> bits colors).
> Now I've got a new project with same LPC2478 but for cost reason we would
> like to use the internal RAM for the LCD :
>
> We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
> The idea is to use 4 bit / pixel (it's enough for this product).
>
> I keep the same project changing only the LCD parameters (width , height
> pulse width ....) and the memory adress (0xA0000000 for sdram and
> 0x40000000 for 64kbyte internal sram.
>
> For variables... I use 16kb sram at adress 0x7FE00000.
I do not believe the LCD controller has AHB or APB access to the 64K SRAM of
the CPU. Datasheet section 7.3 indicates the 64K of RAM is for exclusive
use by the CPU.
Regards,
--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
SolderCore Development Platform http://www.soldercore.com
Reply by ●October 23, 20122012-10-23
The LCD interface is indeed incapable of accessing the main 64k ram or the 16k
ethernet ram on AHB2.
As the user manual (UM10237 ch12.6.1) indicates: "The LCD DMA controller can only access the 10 kB SRAM on AHB1 and the external memory."
And I now see that there is a small error in that one line of text, it should be 16kb.
--
Kevin
--- In l..., "Paul Curtis" wrote:
>
> Hi,
>
> > I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8
> > bits colors).
> > Now I've got a new project with same LPC2478 but for cost reason we would
> > like to use the internal RAM for the LCD :
> >
> > We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
> > The idea is to use 4 bit / pixel (it's enough for this product).
> >
> > I keep the same project changing only the LCD parameters (width , height
> > pulse width ....) and the memory adress (0xA0000000 for sdram and
> > 0x40000000 for 64kbyte internal sram.
> >
> > For variables... I use 16kb sram at adress 0x7FE00000.
>
> I do not believe the LCD controller has AHB or APB access to the 64K SRAM of
> the CPU. Datasheet section 7.3 indicates the 64K of RAM is for exclusive
> use by the CPU.
>
> Regards,
>
> --
> Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> SolderCore Development Platform http://www.soldercore.com
>
As the user manual (UM10237 ch12.6.1) indicates: "The LCD DMA controller can only access the 10 kB SRAM on AHB1 and the external memory."
And I now see that there is a small error in that one line of text, it should be 16kb.
--
Kevin
--- In l..., "Paul Curtis" wrote:
>
> Hi,
>
> > I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8
> > bits colors).
> > Now I've got a new project with same LPC2478 but for cost reason we would
> > like to use the internal RAM for the LCD :
> >
> > We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
> > The idea is to use 4 bit / pixel (it's enough for this product).
> >
> > I keep the same project changing only the LCD parameters (width , height
> > pulse width ....) and the memory adress (0xA0000000 for sdram and
> > 0x40000000 for 64kbyte internal sram.
> >
> > For variables... I use 16kb sram at adress 0x7FE00000.
>
> I do not believe the LCD controller has AHB or APB access to the 64K SRAM of
> the CPU. Datasheet section 7.3 indicates the 64K of RAM is for exclusive
> use by the CPU.
>
> Regards,
>
> --
> Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> SolderCore Development Platform http://www.soldercore.com
>
Reply by ●October 23, 20122012-10-23
Thanks for your help, I will keep the external SDRAM if I have no other
choices...
Sebastien
--- In l..., "Kevin" wrote:
>
> The LCD interface is indeed incapable of accessing the main 64k ram or the 16k ethernet ram on AHB2.
> As the user manual (UM10237 ch12.6.1) indicates: "The LCD DMA controller can only access the 10 kB SRAM on AHB1 and the external memory."
>
> And I now see that there is a small error in that one line of text, it should be 16kb.
>
> --
> Kevin
>
>
>
> --- In l..., "Paul Curtis" wrote:
> >
> > Hi,
> >
> > > I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8
> > > bits colors).
> > > Now I've got a new project with same LPC2478 but for cost reason we would
> > > like to use the internal RAM for the LCD :
> > >
> > > We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
> > > The idea is to use 4 bit / pixel (it's enough for this product).
> > >
> > > I keep the same project changing only the LCD parameters (width , height
> > > pulse width ....) and the memory adress (0xA0000000 for sdram and
> > > 0x40000000 for 64kbyte internal sram.
> > >
> > > For variables... I use 16kb sram at adress 0x7FE00000.
> >
> > I do not believe the LCD controller has AHB or APB access to the 64K SRAM of
> > the CPU. Datasheet section 7.3 indicates the 64K of RAM is for exclusive
> > use by the CPU.
> >
> > Regards,
> >
> > --
> > Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> > SolderCore Development Platform http://www.soldercore.com
>
Sebastien
--- In l..., "Kevin" wrote:
>
> The LCD interface is indeed incapable of accessing the main 64k ram or the 16k ethernet ram on AHB2.
> As the user manual (UM10237 ch12.6.1) indicates: "The LCD DMA controller can only access the 10 kB SRAM on AHB1 and the external memory."
>
> And I now see that there is a small error in that one line of text, it should be 16kb.
>
> --
> Kevin
>
>
>
> --- In l..., "Paul Curtis" wrote:
> >
> > Hi,
> >
> > > I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8
> > > bits colors).
> > > Now I've got a new project with same LPC2478 but for cost reason we would
> > > like to use the internal RAM for the LCD :
> > >
> > > We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
> > > The idea is to use 4 bit / pixel (it's enough for this product).
> > >
> > > I keep the same project changing only the LCD parameters (width , height
> > > pulse width ....) and the memory adress (0xA0000000 for sdram and
> > > 0x40000000 for 64kbyte internal sram.
> > >
> > > For variables... I use 16kb sram at adress 0x7FE00000.
> >
> > I do not believe the LCD controller has AHB or APB access to the 64K SRAM of
> > the CPU. Datasheet section 7.3 indicates the 64K of RAM is for exclusive
> > use by the CPU.
> >
> > Regards,
> >
> > --
> > Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> > SolderCore Development Platform http://www.soldercore.com
>
Reply by ●October 23, 20122012-10-23
Reply by ●October 24, 20122012-10-24
You other alternative is to use a newer part, I've used the LPC18xx and
LPC43xx parts driving the LCD from internal RAM. I believe the LPC178x is also
capable of doing the same.
Reply by ●October 24, 20122012-10-24
--- In l..., "basicnode" wrote:
>
> You other alternative is to use a newer part, I've used the LPC18xx and LPC43xx parts driving the LCD from internal RAM. I believe the LPC178x is also capable of doing the same.
>
LPC178x is only capable to access peripheral RAM and external RAM. But it's a good idea, I will change it for a LPC4357 (it will remove SDRAM and EEprom form my actual board).
Sebastien
>
> You other alternative is to use a newer part, I've used the LPC18xx and LPC43xx parts driving the LCD from internal RAM. I believe the LPC178x is also capable of doing the same.
>
LPC178x is only capable to access peripheral RAM and external RAM. But it's a good idea, I will change it for a LPC4357 (it will remove SDRAM and EEprom form my actual board).
Sebastien
Reply by ●October 24, 20122012-10-24
--- In l..., "sebfr74" wrote:
> I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8 bits colors).
> We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
Please post where you purchased these 7" and 4.3" displays ?
Thanks
don
> I've got a working product using a LPC2478 + SDRAM + 7" TFT display (8 bits colors).
> We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
Please post where you purchased these 7" and 4.3" displays ?
Thanks
don
Reply by ●October 25, 20122012-10-25
@Don,
I purchased both screen at a french company called "Eurocomposant" :
www.eurocomposant.fr
For 7" I use a "Primeview" display with integrated resistive touchscreen
at around 60EUR for 100 parts and for the 4.3", I use a Tianma display
with integrated resistive touchscreen at less than 20EUR / 200 parts
(the Tianma is interesting because it use a single 30 pin connector for
display signals, touchscreen and led backlight. Also it use a single
3.3v power supply and 3.3v signal)
I use in the past Sharp 4.3" but it has 2.5v signals (so you need a
74ALVC164245 chip to translate levels and a second small 4 pin connector
for backlight who's difficult to find).
For both I use a AR1001 touchscreen SPI controller from microchip who
works very nice.
Le 24/10/2012 17:40, Donald H a rit :
>
> --- In l... ,
> "sebfr74" wrote:
>
> > I've got a working product using a LPC2478 + SDRAM + 7" TFT display
> (8 bits colors).
> > We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
>
> Please post where you purchased these 7" and 4.3" displays ?
>
> Thanks
>
> don
>
>
I purchased both screen at a french company called "Eurocomposant" :
www.eurocomposant.fr
For 7" I use a "Primeview" display with integrated resistive touchscreen
at around 60EUR for 100 parts and for the 4.3", I use a Tianma display
with integrated resistive touchscreen at less than 20EUR / 200 parts
(the Tianma is interesting because it use a single 30 pin connector for
display signals, touchscreen and led backlight. Also it use a single
3.3v power supply and 3.3v signal)
I use in the past Sharp 4.3" but it has 2.5v signals (so you need a
74ALVC164245 chip to translate levels and a second small 4 pin connector
for backlight who's difficult to find).
For both I use a AR1001 touchscreen SPI controller from microchip who
works very nice.
Le 24/10/2012 17:40, Donald H a rit :
>
> --- In l... ,
> "sebfr74" wrote:
>
> > I've got a working product using a LPC2478 + SDRAM + 7" TFT display
> (8 bits colors).
> > We use now a 4.3" display (480*272 = 130560 kbyte of RAM in 8 bit depth.
>
> Please post where you purchased these 7" and 4.3" displays ?
>
> Thanks
>
> don
>
>
Reply by ●October 26, 20122012-10-26
On Thu, 2012-10-25 at 08:47 +0200, Sebastien Jacquemard wrote:
> I use a Tianma display
> with integrated resistive touchscreen at less than 20EUR / 200 parts
>
> (the Tianma is interesting because it use a single 30 pin connector for
> display signals, touchscreen and led backlight. Also it use a single
> 3.3v power supply and 3.3v signal)
Hi Sebastien,
Can you please send me the type number of the tianma display ?
thanks,
roelof
> I use a Tianma display
> with integrated resistive touchscreen at less than 20EUR / 200 parts
>
> (the Tianma is interesting because it use a single 30 pin connector for
> display signals, touchscreen and led backlight. Also it use a single
> 3.3v power supply and 3.3v signal)
Hi Sebastien,
Can you please send me the type number of the tianma display ?
thanks,
roelof
