Audio Record/Playback Circuit

[The Master]

Hi, I want to make a circuit that can record short audio clips then play them back through a speaker. The playback needs to be controlled by PIC chips and the audio must be high quality.

I found a component (ISD1000A) that looks like it should do the job. Ive never done anything like this before so i would just like to know if that chip is suitable for what i want.

Im not completely sure what kind of speakers i will be using yet but i assume this device could be connected to an amp for larger speakers.

Does anyone know where to buy these chips from? I found a few webpages that sell them in large quantities but i only want about 10 of them depending on the cost. Ive still not found a site that gives me a price yet.

[ozarkshermit]

I'm not sure about the UK, but these chips (better and larger ones) are available from DIGIKEY in the US. Relatively cheap as well - a 120 second version for $10.18 US DIGIKEY # ISD17120PY-ND
240 second for $12.00 DIGIKEY # ISD17240PY-ND

Or just do a search for CHIPCORDER on DIGIKEY'S site

I'm using both - they are excellent

These were discussed in a previous thread

http://www.picbasic.co.uk/forum/showthread.php?t=9365

Ken

[The Master]

Thanks. Ive had a read through that thread and these chips seem perfect.

If i get one with an SPI interface then can i still use serial on the PIC chip? I just had a look at the datasheet for a PIC16F87 and it seems some of the SPI pins are the same as the RX/TX pins for serial. Is this the same on all PICs or would there be some that can handle both at the same time?

Edit: Im just going to read up on SPI now. Ive never used it before

[The Master]

Ive done some testing using goldwave. I encoded the most important sample using 11.025KHz (the closest option to 12KHz). The quality sounds really bad. Its like being put through a low-pass filter. Would this test be representative of those chips and if so are there any that support a higher sample rate?

[keithdoxey]

Bandwidth is half the sampling frequency so your 11K sample will only have a top end frequency of around 5.5kHz

If you want CD quality then you need to sample at 44.1kHz.

Sampling at 32kHz will give you quality similar to FM radio.

[The Master]

Im not sure what you mean there. I havnt seen bandwidth mentioned anywhere. The datasheet for these chips gives the sampling frequency (max 12KHz) and the tests i did also used sample rate.