PIC 16f877A internal ADC

[Skyheartnet]

Hello all,

I'm currently doing a project on audio amplifier which has an input from mp3 based audio format.I was required to use a microcontroller to control the volume of the output in which my case is to control volume before sending into amplifier(which has fixed gain).Human hearable tone is 20 to 20kHz and i've checked datasheet for 16f877A has a sampling rate of 20MHz but i was advised that the PIC might not be fast enough to support the fast changes of the audio signal,can anyone shed some light on wheather i should still be considering 16f877A PIC thanks.I'm also considering DAC AD7397 to convert digital signal from ADC back to analog,is the two compatible (reason is both are 10-bits) ?

Would be greatfull if anyone knew links that have related to the problems i'm facing thanks.

 

[Nigel Goodwin]

Sampling rate isn't 20MHz (or anywhere near it), that's the maximum clock rate of the PIC.

However, digitising it seems a VERY poor way of controlling the volume - why not just use a digital volume control IC, and use a PIC to set that.

 

[Skyheartnet]

May I ask who much is the sampling rate for the PIC 16f877A or which part of the datasheet can i spot it ?


About ur second quote,I was given the criteria of "Successfully input signal from the analogue world to PIC and convert to its equivalent binary value." which my lecturer told me to use it as the volume control part (coding might involve multiplication of digital bits) .Will this method work ? Or should i just use the digital volume control IC which i'm not sure meets my given criteria or not

Note: I'm still a fresh begineer of using the PIC and its related programing,are there any related sample codes or tutorials regarding the method that i'll be using available to be shared with me?

p.s thanks for the reply,appriciate all the help that is given

 

[blueroomelectronics]

Single channel only about 30kHz, the Microchip site will show how many ksps a particular device will do. The 16 bit parts have faster A/D available.

 

[Nigel Goodwin]

Assuming you're wanting to do volume control actually inside a processor, then I would suggest you go for a dsPIC, you really need a DSP rather than just a micro-controller. Lowering the volume will require dividing the incoming date, and increasing the volume will require multiplication - both of which will be difficult with the ADC running flat out.