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Re: [Discuss-gnuradio] No decimation -- collect at 64MHz
From: |
Johnathan Corgan |
Subject: |
Re: [Discuss-gnuradio] No decimation -- collect at 64MHz |
Date: |
Thu, 10 Jul 2008 11:19:33 -0700 |
On Wed, Jul 9, 2008 at 11:18 PM, Chris Stankevitz <address@hidden> wrote:
>> The gr-radar-mono code does this (there are of course a lot of
>> unrelated customizations to the FPGA code as well).
>
> I'm going to look at this. I'll be back with questions...
There are some nuances. The existing rx_buffer FIFO can only accept
samples at a maximum of 1 sample per 3 clocks. (In the standard build,
it never needs to go even this fast.) Rather than rewriting the
rx_buffer FIFO, which has a lot of Cypress FX2 battle scars in it, I
created a new FIFO (fifo32_2k.v), then joined it to the existing one.
So the 64 Msps samples go into the new FIFO, and a process streams
these out at 1/3 the clock rate into the existing FIFO. Finally, the
samples are streamed out to the USB controller at 1/8 the clock rate.
Look in radar_rx.v for this.
There is a state machine in radar_control.v that drives the
rx_control_o wire to enable all this.
--
Johnathan Corgan
Corgan Enterprises LLC
http://corganenterprises.com/