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Any idea's for a buffer?

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things

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Me and a friend are designing a lasershow controller consisting of a FTDI USB-serial chip and a DAC from Analog, but because the output of a PC is not always steady, we need somehting to buffer the serial data until a new chunk of data is received. Any idea's?

Cheers,
Dan :)
 

things

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Pommie

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Me and a friend are designing a lasershow controller consisting of a FTDI USB-serial chip and a DAC from Analog, but because the output of a PC is not always steady, we need somehting to buffer the serial data until a new chunk of data is received. Any idea's?

Cheers,
Dan :)
There is no device that can buffer data that has not been received. A Pic will buffer the data until more data is required. You will require handshake lines or the Pic will get full up very quick.

Mike.
 

things

New Member
There is no device that can buffer data that has not been received. A Pic will buffer the data until more data is required. You will require handshake lines or the Pic will get full up very quick.

Mike.
Sorry, I didn't mean to buffer invisible data, I meant to buffer the previously sent data untill new data is received.

-Dan ;)
 

things

New Member
hahaha OK :D

Well, essentially, we have the FTDI drivers here for a premade DAC that uses a FTDI chip too, so essentially all we need to do, is interface PC ->FTDI USB - Serial -> Buffer -> DAC and then amp 2 of the DAC outputs to +/-5V differential, and the other channels to just 5-0v, then the rest is just software. Sounds about right, am I missing anything?
 

Pommie

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What speed will the serial be running? Feeding what I assume is a stereo DAC at good quality is a lot of data and will define how you can solve the problem.

Mike.
 

things

New Member
What speed will the serial be running? Feeding what I assume is a stereo DAC at good quality is a lot of data and will define how you can solve the problem.

Mike.
Hi, the DAC chip I linked is 8 channels, 16bit. My friend reckons about 30mhz.

Essentially, we need to amp 2 of those output channels to give us +/-5v, or 10v PTP, and the other 6 are just going to be 0-5V output.

-Dan :)
 

Pommie

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At that speed you need to look at one of the FTDI chips/modules with built in fifo. A pic is not a good choice.

Mike.
 

Nigel Goodwin

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At that speed you need to look at one of the FTDI chips/modules with built in fifo. A pic is not a good choice.
That value sounds incredibly high, the original post was for a laser light display - you're not going to need anything terribly fast for that, and do you really need 16 bit?, would it give any advantage?.
 

things

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The galvanometers can range all the way up to like 40,000 points per second, and we are aiming for just over 30,000 points per second, so it needs to be relatively fast. Using 16bit would mean better resolution, and many laser show controllers use 16bit.
 

Hayato

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30,000 points per second = 40 kHz, not 30MHz.

You'll need something around 640 kHz or 1MHz but no more than 1MHz.
 

things

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