🚀 go-pugleaf

In article 19631@cc.uow.edu.au, u8801763@cc.uow.edu.au (Radivoj Kouzan) writes:
>u9066624@cc.uow.edu.au (Tippu Hassan) writes:
>
>>Hello anyone,
>
>>My name is Tippu and I live in Australia. I am working with the TI
>>"SWDS" (Software Development Systems) board which is a support tool
>>for the TMS320C25 dsp chip. I am using the TMS320C25 serial port to
>>read in digitized speech samples and then storing them on external
>>RAM memory which is on the SWDS board. The SWDS only has 32K bytes
>>of onboard RAM avialable and therefore I can only store 2 seconds
>>worth of 16-bit digitized speech. So in order to record continous
>>speech I am using the cpu processor to upload these speech samples
>>from the SWDS board RAM and store them on files once the RAM is full. 
>>This is done via C applications written for the cpu. 
>>My problem is that in order for the cpu to access the SWDS RAM once 
>>it is full, it MUST place the TMS320C25 in halt mode, then upload 
>>the speech samples and then unhalt the TMS320C25 to resume reading 
>>in the next load of speech samples. But the cpu cannot execute this 
>>process quite enough, and TMS320C25 loses some speech samples while 
>>it is halted. I cannot uses the grep command on the TMS320C25, which
>>makes the external RAM global, because it requires external circuitry
>>for the TMS320C25 and it is wired onto the SWDS board. Can anyone offer
>>any ideas or help as it would be much appreciated.
>
>
>
>
>Sell it and buy yourself a DSP that works for Digital Signals.



I was once using  a TMS320C20 based add-on board to digitize and process
speech data. We used a double-buffering scheme wherein the DSP chip raise
a semaphore after filling one buffer and continues filling the second buffer,
while the CPU will start reading the data from the first buffer once the semaphore
is raised. This scheme worked pretty well for TMS320c20, which we were able to 
access upto register level from the PC side( not like the systems which hide the 
internals by giving you a set of function calls or a library ! ). I don't know if you've
tried this but this is one of the most commonly used method to get data without
halting the DSP chip.

Murali.

P.S : the semaphore was a software one and we used a memory location accessible 
       by both DSP and PC CPU for that purpose.  I suppose you have that kind of 
       dual-ported memory in your system.