Need good quality Audio output through LPC21xx controller

We are working on a project based on Vehicle tracking system.In one of
our module we are using audio(voice)  for Public transport  system.As
if for now we are using  filters and a power amplifer We are not able
to get good quality audio output with this setup.

Item used:
Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
Audio Amplifier+ Speaker

Requirement:


Good Voice quality annoucement system for Public transport System

On Mon, 29 Sep 2008 22:28:18 -0700 (PDT), in comp.arch.embedded
angaddhot@gmail.com wrote:

>We are working on a project based on Vehicle tracking system.In one of
>our module we are using audio(voice)  for Public transport  system.As
>if for now we are using  filters and a power amplifer We are not able
>to get good quality audio output with this setup.
>
>Item used:
>Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
>Audio Amplifier+ Speaker
>
>Requirement:
>
>
>Good Voice quality annoucement system for Public transport System
Are you trying to use PWM to play the audio, or a  DAC?
How are you recording the audio, bit rate and depth?

martin

On Sep 30, 1:23=A0pm, Martin Griffith <mart_in_med...@yah00.es> wrote:
> On Mon, 29 Sep 2008 22:28:18 -0700 (PDT), in comp.arch.embedded
>
> angadd...@gmail.com wrote:
> >We are working on a project based on Vehicle tracking system.In one of
> >our module we are using audio(voice) =A0for Public transport =A0system.A=
s
> >if for now we are using =A0filters and a power amplifer We are not able
> >to get good quality audio output with this setup.
>
> >Item used:
> >Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
> >Audio Amplifier+ Speaker
>
> >Requirement:
>
> >Good Voice quality annoucement system for Public transport System
>
> Are you trying to use PWM to play the audio, or a =A0DAC?
> How are you recording the audio, bit rate and depth?
>
> mar


I am using PWM ,.raw format little indian 16 bit 8khz<

Op Tue, 30 Sep 2008 07:28:18 +0200 schreef <angaddhot@gmail.com>:
> We are working on a project based on Vehicle tracking system.In one of
> our module we are using audio(voice)  for Public transport  system.As
> if for now we are using  filters and a power amplifer We are not able
> to get good quality audio output with this setup.

How?  What's wrong with the quality?  (Frequency response/THD  
distortion/Noise/Effective rms power)

> Item used:
> Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+

Why do you need these filters?

> Audio Amplifier+ Speaker

Are your amplifier and speaker suitable for "good voice quality" ?

> Requirement:
>
>
> Good Voice quality annoucement system for Public transport System

Is your clock crystal stable enough for "good voice quality" ?


-- 
Gemaakt met Opera's revolutionaire e-mailprogramma:  
http://www.opera.com/mail/

angaddhot@gmail.com wrote:

> We are working on a project based on Vehicle tracking system.In one of
> our module we are using audio(voice)  for Public transport  system.As
> if for now we are using  filters and a power amplifer We are not able
> to get good quality audio output with this setup.
> 
> Item used:
> Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
> Audio Amplifier+ Speaker
> 
> Requirement:
> 
> Good Voice quality annoucement system for Public transport System

With PWM at 32kHz carrier and 8bit quantization, you can get a 
"telephone line" quality speech. It would be even better if you apply 
the preemphasis and the noise shaping to the recorded signal. You can 
gain somewhat more quality if you combine several PWM channels. However 
if you need the "music" quality audio, you should use an external DAC.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

On Sep 30, 6:56=A0pm, Vladimir Vassilevsky <antispam_bo...@hotmail.com>
wrote:
> angadd...@gmail.com wrote:
> > We are working on a project based on Vehicle tracking system.In one of
> > our module we are using audio(voice) =A0for Public transport =A0system.=
As
> > if for now we are using =A0filters and a power amplifer We are not able
> > to get good quality audio output with this setup.
>
> > Item used:
> > Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
> > Audio Amplifier+ Speaker
>
> > Requirement:
>
> > Good Voice quality annoucement system for Public transport System
>
> With PWM at 32kHz carrier and 8bit quantization, you can get a
> "telephone line" quality speech. It would be even better if you apply
> the preemphasis and the noise shaping to the recorded signal. You can
> gain somewhat more quality if you combine several PWM channels. However
> if you need the "music" quality audio, you should use an external DAC.
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Design Consultanthttp://www.abvolt.com

What about DAC codec ??
It needs I2S interface which is not available with LPC21XX.
If anyone know how to convert SSP from microcontroller controller to
I2S format in software.

angaddhot@gmail.com wrote:

> On Sep 30, 6:56 pm, Vladimir Vassilevsky <antispam_bo...@hotmail.com>
> wrote:
> 
>>With PWM at 32kHz carrier and 8bit quantization, you can get a
>>"telephone line" quality speech. It would be even better if you apply
>>the preemphasis and the noise shaping to the recorded signal. You can
>>gain somewhat more quality if you combine several PWM channels. However
>>if you need the "music" quality audio, you should use an external DAC.
>>

> What about DAC codec ??
> It needs I2S interface which is not available with LPC21XX.
> If anyone know how to convert SSP from microcontroller controller to
> I2S format in software.

I can do that for you, however this is going to be business.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

angaddhot@gmail.com wrote:
> On Sep 30, 6:56 pm, Vladimir Vassilevsky <antispam_bo...@hotmail.com>
> wrote:
>> angadd...@gmail.com wrote:
>>> We are working on a project based on Vehicle tracking system.In one of
>>> our module we are using audio(voice)  for Public transport  system.As
>>> if for now we are using  filters and a power amplifer We are not able
>>> to get good quality audio output with this setup.
>>> Item used:
>>> Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
>>> Audio Amplifier+ Speaker
>>> Requirement:
>>> Good Voice quality annoucement system for Public transport System
>> With PWM at 32kHz carrier and 8bit quantization, you can get a
>> "telephone line" quality speech. It would be even better if you apply
>> the preemphasis and the noise shaping to the recorded signal. You can
>> gain somewhat more quality if you combine several PWM channels. However
>> if you need the "music" quality audio, you should use an external DAC.
>>
>> Vladimir Vassilevsky
>> DSP and Mixed Signal Design Consultanthttp://www.abvolt.com
> 
> What about DAC codec ??
> It needs I2S interface which is not available with LPC21XX.
> If anyone know how to convert SSP from microcontroller controller to
> I2S format in software.

Hi!

Use LPC2141-LPC2148 instead (have USB, RTC...), possibly cheaper than 
LPC2132, and is much faster (interleaved flash...):

LPC2141, LPC2142, LPC2144, LPC2146, and LPC2148 device highlight:
http://www.standardics.nxp.com/products/lpc2000/lpc214x/~LPC2148/

LPC2148:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=568-1765-ND

LPC2141:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=568-1761-ND

Example:
MP3/AAC player decoded in the ARM processor:
http://www.mikrocontroller.net/articles/ARM_MP3/AAC_Player

ARM7 LPC2148 mini board:
http://www.scienceprog.com/arm7-lpc2148-mini-board/
ARM7-Base development board for LPC2148:
http://www.scienceprog.com/arm7-base-development-board-for-lpc2148/
First LPC2148 ARM7 microcontroller test&#4294967295;led blink:
http://www.scienceprog.com/first-lpc2148-arm7-microcontroller-test-led-blink/
RTC example on ARM7 LPC2148 using WinARM:
http://www.scienceprog.com/rtc-example-on-arm7-lpc2148-using-winarm/

/Glenn

<angaddhot@gmail.com> skrev i meddelandet 
news:0f148d36-bf58-48e7-9a34-1db113920ee2@v15g2000hsa.googlegroups.com...
On Sep 30, 6:56 pm, Vladimir Vassilevsky <antispam_bo...@hotmail.com>
wrote:
> angadd...@gmail.com wrote:
> > We are working on a project based on Vehicle tracking system.In one of
> > our module we are using audio(voice) for Public transport system.As
> > if for now we are using filters and a power amplifer We are not able
> > to get good quality audio output with this setup.
>
> > Item used:
> > Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
> > Audio Amplifier+ Speaker
>
> > Requirement:
>
> > Good Voice quality annoucement system for Public transport System
>
> With PWM at 32kHz carrier and 8bit quantization, you can get a
> "telephone line" quality speech. It would be even better if you apply
> the preemphasis and the noise shaping to the recorded signal. You can
> gain somewhat more quality if you combine several PWM channels. However
> if you need the "music" quality audio, you should use an external DAC.
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Design Consultanthttp://www.abvolt.com

What about DAC codec ??
It needs I2S interface which is not available with LPC21XX.
If anyone know how to convert SSP from microcontroller controller to
I2S format in software.

==> There are plenty of controllers out there with I2S.
        The AVR32 based UC3A3 has SD-Card I/F,
        High speed USB, and I2S (as well as ADC/DAC)
        Should be considerably faster than the LPC as well.

        If you insist on ARM cores, then the AT91SAM7A3
        has SD-Card interface and I2S interface (SSC).

-- 
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB 

On Sep 30, 11:00=A0pm, "Ulf Samuelsson" <u...@a-t-m-e-l.com> wrote:
> <angadd...@gmail.com> skrev i meddelandetnews:0f148d36-bf58-48e7-9a34-1db=
113920ee2@v15g2000hsa.googlegroups.com...
> On Sep 30, 6:56 pm, Vladimir Vassilevsky <antispam_bo...@hotmail.com>
> wrote:
>
>
>
> > angadd...@gmail.com wrote:
> > > We are working on a project based on Vehicle tracking system.In one o=
f
> > > our module we are using audio(voice) for Public transport system.As
> > > if for now we are using filters and a power amplifer We are not able
> > > to get good quality audio output with this setup.
>
> > > Item used:
> > > Lpc2132 with MMC card interface ,High pass filter+ Low pass filter+
> > > Audio Amplifier+ Speaker
>
> > > Requirement:
>
> > > Good Voice quality annoucement system for Public transport System
>
> > With PWM at 32kHz carrier and 8bit quantization, you can get a
> > "telephone line" quality speech. It would be even better if you apply
> > the preemphasis and the noise shaping to the recorded signal. You can
> > gain somewhat more quality if you combine several PWM channels. However
> > if you need the "music" quality audio, you should use an external DAC.
>
> > Vladimir Vassilevsky
> > DSP and Mixed Signal Design Consultanthttp://www.abvolt.com
>
> What about DAC codec ??
> It needs I2S interface which is not available with LPC21XX.
> If anyone know how to convert SSP from microcontroller controller to
> I2S format in software.
>
> =3D=3D> There are plenty of controllers out there with I2S.
> =A0 =A0 =A0 =A0 The AVR32 based UC3A3 has SD-Card I/F,
> =A0 =A0 =A0 =A0 High speed USB, and I2S (as well as ADC/DAC)
> =A0 =A0 =A0 =A0 Should be considerably faster than the LPC as well.
>
> =A0 =A0 =A0 =A0 If you insist on ARM cores, then the AT91SAM7A3
> =A0 =A0 =A0 =A0 has SD-Card interface and I2S interface (SSC).
>
> --
> Best Regards,
> Ulf Samuelsson
> This is intended to be my personal opinion which may,
> or may not be shared by my employer Atmel Nordic AB

------------  > Its not possiable to change the controller ,I want to
know how can i convert SPI1 mode to I2S ,give me the code