Hi!
Is it possible to use external 8-bit SRAM for frame buffer for LCD with
LPC2478?
M.
LPC2478 + external SRAM + LCD
Started by ●November 25, 2008
Reply by ●November 25, 20082008-11-25
At 10:39 25.11.2008 +0100, you wrote:
>Hi!
>
>Is it possible to use external 8-bit SRAM for frame buffer for LCD with
>LPC2478?
Yes, you can even use the internal RAM if the size is enough for your
display. There is a bandwidth calculator on the NXP website showing
how much traffic one can expect on the bus for the display refresh.
Herbert
>M.
>
>
>Hi!
>
>Is it possible to use external 8-bit SRAM for frame buffer for LCD with
>LPC2478?
Yes, you can even use the internal RAM if the size is enough for your
display. There is a bandwidth calculator on the NXP website showing
how much traffic one can expect on the bus for the display refresh.
Herbert
>M.
>
>
Reply by ●November 25, 20082008-11-25
Thanks!
I calculated and got about 15% load with 8 bit SRAM. Is this crytical?
Marko
Herbert Demmel pravi:
> At 10:39 25.11.2008 +0100, you wrote:
>
>> Hi!
>>
>> Is it possible to use external 8-bit SRAM for frame buffer for LCD with
>> LPC2478?
>>
>
> Yes, you can even use the internal RAM if the size is enough for your
> display. There is a bandwidth calculator on the NXP website showing
> how much traffic one can expect on the bus for the display refresh.
>
> Herbert
>
>
I calculated and got about 15% load with 8 bit SRAM. Is this crytical?
Marko
Herbert Demmel pravi:
> At 10:39 25.11.2008 +0100, you wrote:
>
>> Hi!
>>
>> Is it possible to use external 8-bit SRAM for frame buffer for LCD with
>> LPC2478?
>>
>
> Yes, you can even use the internal RAM if the size is enough for your
> display. There is a bandwidth calculator on the NXP website showing
> how much traffic one can expect on the bus for the display refresh.
>
> Herbert
>
>
Reply by ●November 25, 20082008-11-25
At 11:36 25.11.2008 +0100, you wrote:
>Thanks!
>
>I calculated and got about 15% load with 8 bit SRAM. Is this crytical?
No, not really. If you do not want to have a lot of other traffic via
the external bus, it's rather peanuts. Note, that when executing from
the internal flash and reading/writing the internal RAM no speed
decrease will happen due to the frame buffer refresh.
Herbert
>Marko
>
>Herbert Demmel pravi:
> > At 10:39 25.11.2008 +0100, you wrote:
> >
> >> Hi!
> >>
> >> Is it possible to use external 8-bit SRAM for frame buffer for LCD with
> >> LPC2478?
> >>
> >
> > Yes, you can even use the internal RAM if the size is enough for your
> > display. There is a bandwidth calculator on the NXP website showing
> > how much traffic one can expect on the bus for the display refresh.
> >
> > Herbert
> >
> >
>
>Thanks!
>
>I calculated and got about 15% load with 8 bit SRAM. Is this crytical?
No, not really. If you do not want to have a lot of other traffic via
the external bus, it's rather peanuts. Note, that when executing from
the internal flash and reading/writing the internal RAM no speed
decrease will happen due to the frame buffer refresh.
Herbert
>Marko
>
>Herbert Demmel pravi:
> > At 10:39 25.11.2008 +0100, you wrote:
> >
> >> Hi!
> >>
> >> Is it possible to use external 8-bit SRAM for frame buffer for LCD with
> >> LPC2478?
> >>
> >
> > Yes, you can even use the internal RAM if the size is enough for your
> > display. There is a bandwidth calculator on the NXP website showing
> > how much traffic one can expect on the bus for the display refresh.
> >
> > Herbert
> >
> >
>
Reply by ●November 25, 20082008-11-25
Looks good.
Just one final question. I was reading LPC2478UM for configuration, but
not very deeply at the moment. Here's my situation: my panel has 3x8bits
RGB interface, the external SRAM will be 8-bit and I would like to use
8bpp via pallete. Is this possible, or I need 32bit wide external memory?
Marko
Herbert Demmel pravi:
> At 11:36 25.11.2008 +0100, you wrote:
>
>> Thanks!
>>
>> I calculated and got about 15% load with 8 bit SRAM. Is this crytical?
>>
>
> No, not really. If you do not want to have a lot of other traffic via
> the external bus, it's rather peanuts. Note, that when executing from
> the internal flash and reading/writing the internal RAM no speed
> decrease will happen due to the frame buffer refresh.
>
> Herbert
>
>
>> Marko
>>
>> Herbert Demmel pravi:
>>
>>> At 10:39 25.11.2008 +0100, you wrote:
>>>
>>>
>>>> Hi!
>>>>
>>>> Is it possible to use external 8-bit SRAM for frame buffer for LCD with
>>>> LPC2478?
>>>>
>>>>
>>> Yes, you can even use the internal RAM if the size is enough for your
>>> display. There is a bandwidth calculator on the NXP website showing
>>> how much traffic one can expect on the bus for the display refresh.
>>>
>>> Herbert
>>>
>>>
>>>
Just one final question. I was reading LPC2478UM for configuration, but
not very deeply at the moment. Here's my situation: my panel has 3x8bits
RGB interface, the external SRAM will be 8-bit and I would like to use
8bpp via pallete. Is this possible, or I need 32bit wide external memory?
Marko
Herbert Demmel pravi:
> At 11:36 25.11.2008 +0100, you wrote:
>
>> Thanks!
>>
>> I calculated and got about 15% load with 8 bit SRAM. Is this crytical?
>>
>
> No, not really. If you do not want to have a lot of other traffic via
> the external bus, it's rather peanuts. Note, that when executing from
> the internal flash and reading/writing the internal RAM no speed
> decrease will happen due to the frame buffer refresh.
>
> Herbert
>
>
>> Marko
>>
>> Herbert Demmel pravi:
>>
>>> At 10:39 25.11.2008 +0100, you wrote:
>>>
>>>
>>>> Hi!
>>>>
>>>> Is it possible to use external 8-bit SRAM for frame buffer for LCD with
>>>> LPC2478?
>>>>
>>>>
>>> Yes, you can even use the internal RAM if the size is enough for your
>>> display. There is a bandwidth calculator on the NXP website showing
>>> how much traffic one can expect on the bus for the display refresh.
>>>
>>> Herbert
>>>
>>>
>>>
Reply by ●November 25, 20082008-11-25
At 15:16 25.11.2008 +0100, you wrote:
>Looks good.
>
>Just one final question. I was reading LPC2478UM for configuration, but
>not very deeply at the moment.
You *should* do that ...
>Here's my situation: my panel has 3x8bits
>RGB interface, the external SRAM will be 8-bit and I would like to use
>8bpp via pallete. Is this possible, or I need 32bit wide external memory?
The bus-width of your SRAM has nothing to do with the number of bits
you use for the LCD. Otherwise you would not be able to store e.g.
word or integer data into the SRAM ...
Herbert
>Looks good.
>
>Just one final question. I was reading LPC2478UM for configuration, but
>not very deeply at the moment.
You *should* do that ...
>Here's my situation: my panel has 3x8bits
>RGB interface, the external SRAM will be 8-bit and I would like to use
>8bpp via pallete. Is this possible, or I need 32bit wide external memory?
The bus-width of your SRAM has nothing to do with the number of bits
you use for the LCD. Otherwise you would not be able to store e.g.
word or integer data into the SRAM ...
Herbert
