High ADC sampling rate PIC, 18F needed? - Page 2 - Electronic Circuits Projects Diagrams Free

Sceadwian · 1st October 2007, 05:38 AM

This is why you use an external ADC. You then don't have to worry about high frequency noise quiet as much as the ADC unit isn't on the same die as the digital portions. If this is for basic audio try closer to 8khz. Only hi-fi music needs the higher sampling rates.

bananasiong · 1st October 2007, 08:04 AM

That's not for hi-fi music, just simply the audio output from the MP3 player.
Even I can lower the sampling rate, but I think the speed of the PIC need to be fast enough to perform faster serial transmission.

**Nigel Goodwin** · 1st October 2007, 09:12 AM

Quote:

Originally Posted by bananasiong

That's not for hi-fi music, just simply the audio output from the MP3 player.
Even I can lower the sampling rate, but I think the speed of the PIC need to be fast enough to perform faster serial transmission.

What speed serial transmission are you planning?.

bananasiong · 1st October 2007, 05:13 PM

I have not decided yet. I'm hoping to send out the serial data before the second data being sampled so that I have enough time to do something else. Maybe UART will be used for the transmission, I'm still doing research on that.

**Nigel Goodwin** · 1st October 2007, 11:30 PM

Quote:

Originally Posted by bananasiong

I have not decided yet. I'm hoping to send out the serial data before the second data being sampled so that I have enough time to do something else. Maybe UART will be used for the transmission, I'm still doing research on that.

You need to work it out first - and seriously need a hardware UART, as your timing requirements are so tight.

Gordz · 28th October 2007, 12:46 PM

The PIC24HJ12GP202 or similar will allow you to sample 10bit AD @ 1.1 msps, it also has the ability to store direct to internal ram. But I am having trouble trying to get any .ASM support for this range.

**Nigel Goodwin** · 28th October 2007, 12:58 PM

Quote:

Originally Posted by Gordz

The PIC24HJ12GP202 or similar will allow you to sample 10bit AD @ 1.1 msps, it also has the ability to store direct to internal ram. But I am having trouble trying to get any .ASM support for this range.

Presumably, like the 18F series, support is for C programming, with a free compiler available?.

Gordz · 28th October 2007, 01:03 PM

You got it right there. It's a hassle because I wanted to port my 'scope code from the 18F I'm using to the 24HJ12GP202 to take adavntage of the A/D speed. Microchip have not been able to help and I'm not about to start learning C so I now spend hours searching and trying to get a 'hello world' working.....

**Nigel Goodwin** · 28th October 2007, 01:05 PM

Quote:

Originally Posted by Gordz

You got it right there. It's a hassle because I wanted to port my 'scope code from the 18F I'm using to the 24HJ12GP202 to take adavntage of the A/D speed. Microchip have not been able to help and I'm not about to start learning C so I now spend hours searching and trying to get a 'hello world' working.....

I'm also 'anti-C' but for the 18F and higher series it's something you really need to learn, because that's what they are intended for, and application notes and examples are in C. Obviously you could use assembler for time critical sections, and presumably all the assembler codes are in the datasheet?.

Gordz · 28th October 2007, 01:13 PM

The code is there in as much as it is listed, however it is not very clear. There are no code template available and was I have found has been from dsPIC models. From what I have piced to gether there is no reason why my 'hello world' won't work but the PIC does not seem to be running so the clock is probably not configured. That in it's self is more than a little complicated with so many options. Even if I learned C (old dog new tricks etc.) I would still need to port all the .ASM stuff I have.

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1st October 2007, 05:38 AM	(permalink)
Sceadwian	This is why you use an external ADC. You then don't have to worry about high frequency noise quiet as much as the ADC unit isn't on the same die as the digital portions. If this is for basic audio try closer to 8khz. Only hi-fi music needs the higher sampling rates. __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har."

1st October 2007, 08:04 AM	(permalink)
bananasiong	That's not for hi-fi music, just simply the audio output from the MP3 player. Even I can lower the sampling rate, but I think the speed of the PIC need to be fast enough to perform faster serial transmission. __________________ Superman returns..

1st October 2007, 05:13 PM	(permalink)
bananasiong	I have not decided yet. I'm hoping to send out the serial data before the second data being sampled so that I have enough time to do something else. Maybe UART will be used for the transmission, I'm still doing research on that. __________________ Superman returns..

28th October 2007, 12:46 PM	(permalink)
Gordz	The PIC24HJ12GP202 or similar will allow you to sample 10bit AD @ 1.1 msps, it also has the ability to store direct to internal ram. But I am having trouble trying to get any .ASM support for this range.

28th October 2007, 01:03 PM	(permalink)
Gordz	You got it right there. It's a hassle because I wanted to port my 'scope code from the 18F I'm using to the 24HJ12GP202 to take adavntage of the A/D speed. Microchip have not been able to help and I'm not about to start learning C so I now spend hours searching and trying to get a 'hello world' working.....

28th October 2007, 01:13 PM	(permalink)
Gordz	The code is there in as much as it is listed, however it is not very clear. There are no code template available and was I have found has been from dsPIC models. From what I have piced to gether there is no reason why my 'hello world' won't work but the PIC does not seem to be running so the clock is probably not configured. That in it's self is more than a little complicated with so many options. Even if I learned C (old dog new tricks etc.) I would still need to port all the .ASM stuff I have.