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X10A Freedom
post Oct 27 2005, 10:00 PM

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QUOTE(martianunlimited @ Oct 27 2005, 08:56 PM)
Haha. gimme a while need to look up what in the world is a veterbi decoder....
Okie, it's a transciever with encoder/decoder.  Sorry I am not involved with with these types of circuits. And i can't believe that i need to read up on trellis coding to remember how it works. Sigh that's what happens when you don't touch communication for a few years...

anyway I assume you already know the information here... http://www2.ing.puc.cl/~iee3552/TCM.PDF

Based on the block diagram here, This is what i will do, i will implement the decoder,  (and control blocks) in verilog/VHDL or systemC (your choice, just so that i can synthesize it and save myself time). You will have to blackbox the demodulator block; (allocate some space for your layout so that the place and route tool won't accidentally route around that area and cause problems with your routing later).
The circuit demodulator block will need to be designed by hand; from the diagram it appears that all the viterbi decoder need is the recieved data. so just send the recieved data; with a clock;  and the control block should be sending and recieving control signals to both the demodulator and the decoder.

After you have your demodulator circuit, then just draw the layout and connect it to the verilog synthesized portion.

(verilog for viterbi decoder: http://www-ee.eng.hawaii.edu/~msmith/ASICs...11/CH11.12.htm) I shouldn't be doing this but i wanted to verify whether or not the decoder is really synthesizable

Side note: regarding your question to convert verilog to schematic, most synthesis tools, and formal verification tools should have that capability (some accepts only synthesized verilog so you may need to do just that)

Just curious is this wired or wireless? It's possible to build an antenna on a chip, but i have no idea how it's done.
*
haha, probably should have stated my question properly, how do you model a Viterbi decoder in terms functional block(like general idea in modelling the branch metric unit etc) tongue.gif but anyways, don't think u might remember back since u haven't been touching this for some time
coz i realize to implement the algorithm/trellis diagram in terms of hardware is kinda headache......
i already know the process that you mentioned to me(coz my supervisor did brief me on a brief process flow), thanks anyways
anyways, mind telling me wat synthesis tools is that? coz our college don't seem to have that tool(unless our supervisor doesn't want us to use)
actually currently i'm avoiding the black box process and try to model it using functional block immediately, that way i can model the schematic form much more easily

p/s: i only need to model out the IC, doesn't matter whether it's wired or wireless
but the algorithm i'm using is similar to those used in WCDMA
the link you posted won't be any help to me coz i'm using hard decision decoding and a convolutional length of 7(which makes it 64 states sweat.gif)

This post has been edited by X10A Freedom: Oct 27 2005, 10:17 PM
martianunlimited
post Oct 27 2005, 10:20 PM

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QUOTE(X10A Freedom @ Oct 27 2005, 10:00 PM)
haha, probably should have stated my question properly, how do you model a Viterbi decoder in terms functional block tongue.gif but anyways, don't think u might remember back since u haven't been touching this for some time
coz i realize to implement the algorithm/trellis diagram in terms of hardware is kinda headache......
i already know the process that you mentioned to me(coz my supervisor did brief me on a brief process flow), thanks anyways
anyways, mind telling me wat synthesis tools is that? coz our college don't seem to have that tool(unless our supervisor doesn't want us to use)
actually currently i'm avoiding the black box process and try to model it using functional block immediately, that way i can model the schematic form much more easily
*
See the verilog here tongue.gif http://www-ee.eng.hawaii.edu/~msmith/ASICs...H11/CH11.12.htm
Then synthesize it tongue.gif (or you can synthesize it by hand.. shouldn't be that hard, i see mux statements; and +1 statement (incrementer (use T-flip-flops?) *edit... nix that... i just realized the decoder code is at the bottom*
well.. from the verilog you should be able to build block diagrams (just divide them by module) then later "synthesize" each of the block by hand...

I can't give the name of the synthesis tool we use (corporate policy), what i can give you is the list of synthesis tools you can use.
Side note... i don't think any college have license for synthesis tools; they are just too expensive. (they pay more for 1 license than what they pay 10 engineers) (but makes sense, these tools can do the job of 10 engineers)
Cadence's Encounter (RTL compiler)
Forte's Cynthesizer
Mentor Graphic's Precision Synthesis Tool
Synopsys' Design Compiler

This post has been edited by martianunlimited: Oct 27 2005, 10:31 PM
X10A Freedom
post Oct 27 2005, 11:01 PM

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hehe, still, as i said, it's pretty useless coz the link u provided is using soft-decision method which includes quatizations etc
for hard-decision method, it's much more direct but currently still figuring out how to implement it
so far i've been thinking of using ROMs to determine the branch metrics since it's pretty much set throughout the whole process.......for the ACS, still thinking
Mentor Graphics's Precision Synthesis Tool? hmmm........interesting.......does it synthesis in terms of blocks or the circuit schemetic(like logic circuits)?
martianunlimited
post Oct 27 2005, 11:10 PM

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Synthesis tools basically converts verilog statements and equations to logic gates/flops (so the answer is yes.. you get the logic circuits)

you can get the block level (dataflow diagram?) from the unsynthesized verilog (behaivorial verilog)

It will be in a structural verilog AKA synthesized verilog
if you want the schematic, all you need is a verilog viewer, (i believe gatevision is another example) (but there is a license involved with it)


This post has been edited by martianunlimited: Oct 27 2005, 11:14 PM
X10A Freedom
post Oct 27 2005, 11:14 PM

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QUOTE(martianunlimited @ Oct 27 2005, 11:10 PM)
Synthesis tools basically converts verilog statements and equations to logic gates/flops (so the answer is yes..)
*
oh, thanks for the info
looks like i have 1 thing less to worry
XD
halo
post Nov 3 2005, 05:47 PM

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guys, i hav a question here, regarding FPU. i'm currently working on normalizing the result, i hav somehow figured out the algo to do it, but i would like to know if there's any good algo for it. thanks smile.gif
ikanayam
post Nov 3 2005, 05:54 PM

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QUOTE(halo @ Nov 3 2005, 04:47 AM)
guys, i hav a question here, regarding FPU. i'm currently working on normalizing the result, i hav somehow figured out the algo to do it, but i would like to know if there's any good algo for it. thanks smile.gif
*
Depends on how much hardware you're willing to spend on it and how fast you want to do it. Need many many more details before that question can be answered.
halo
post Nov 3 2005, 06:08 PM

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okie, thanks for the feedback. my goal is to achieve minimum delay in terms of gate level and the fastest algo. And i need to normalize an 8-bit result.

any more info needed? smile.gif

This post has been edited by halo: Nov 3 2005, 06:11 PM
X10A Freedom
post Nov 3 2005, 06:08 PM

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anyone here know how JTAG works and all? if better u have the pdf files for the actual IEEE specifications
don't ask me to google it as it's impossible
unless someone from edaboards.com can give me coz my points are kinda limited tongue.gif
ikanayam
post Nov 3 2005, 06:26 PM

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QUOTE(halo @ Nov 3 2005, 05:08 AM)
okie, thanks for the feedback. my goal is to achieve minimum delay in terms of gate level and the fastest algo. And i need to normalize an 8-bit result.

any more info needed? smile.gif
*
it has to be done in 1 clock? Need full details of the FP format to get a better idea. Do you have to support denormals? Details details.
halo
post Nov 3 2005, 08:47 PM

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my fp format is :- 16-bit only, 1 for sign bit, 7 for biased exponent, 8 for mantissa, support denormals aso

now after add/sub the mantissa, i need to normalize it to 0.1XXXXXXX before storing the result.

TScharge-n-go
post Nov 3 2005, 10:04 PM

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anybody has good slides on the algorithm about Manchester Carry Chain adder? I found a lot from google, but most of them are talking about transistor optimization (which i never learn b4 sad.gif ). I only got a lil tips tat Manchester is using some carry skip and carry lookahead method to speed up the process.

Implementation : 4x 8-bit adder for halo's FADD unit. Need a small, low power and decent speed adder. From some graph i found manchester suits this, anymore recommendation about which adder to be used?

Thanx a lot notworthy.gif
martianunlimited
post Nov 3 2005, 10:32 PM

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I don't have any experience with a manchester carry chain adder, but if you want to know how a carry look ahead adder work here is the wiki
http://en.wikipedia.org/wiki/Carry_lookahead_adder

CLAs are quite easy to design, and the implementation is quite simple, from what i googled, a manchester carry chain looks like a domino implementation of a lookahead circuit

For 8 bits you can do something like this 8 half-adder -> 2 4bit CL -> 1 2bit CL
(or 3 3bit CL -> 1 3bit CL) ( i think second implementation should have a lower delay)

This post has been edited by martianunlimited: Nov 3 2005, 10:37 PM
TScharge-n-go
post Nov 4 2005, 12:43 AM

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I already have a couple of CL and CR hybrid. Just wanna try if MCC or some Carry Skip can give me good results for 8-bit tongue.gif
ikanayam
post Nov 4 2005, 02:55 AM

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QUOTE(halo @ Nov 3 2005, 07:47 AM)
my fp format is :- 16-bit only, 1 for sign bit, 7 for biased exponent, 8 for mantissa, support denormals aso

now after add/sub the mantissa, i need to normalize it to 0.1XXXXXXX before storing the result.
*
So there's the implied bit after the decimal place for non denormals?
halo
post Nov 4 2005, 06:09 PM

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1XXX will be stored, so there will b no implied bit after the decimal place
is there any way to do it within one clock cycle, at gate level instead of transistor level?

TScharge-n-go
post Nov 4 2005, 06:28 PM

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halo, maybe can ask shabiul for help tongue.gif (JKJK). According to martianunlimited suggestions previously, i already have a few 8-bit adders for you. Choose one to suit yr multi adder FP unit design, hehehe.


btw, anybody knows how to calculate the delay due to the increase of fan-in? Thanx
ikanayam
post Nov 5 2005, 01:44 AM

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QUOTE(halo @ Nov 4 2005, 05:09 AM)
1XXX will be stored, so there will b no implied bit after the decimal place
is there any way to do it within one clock cycle, at gate level instead of transistor level?
*
Yes you can do it in one clock, you need to use a barrel shifter or eight 8-to-1 multiplexors. Both of which will consume a significant amount of hardware. You'll also need a subtractor to determine the difference in the exponents to give you the number of bits you have to shift.



QUOTE(charge-n-go @ Nov 4 2005, 05:28 AM)
halo, maybe can ask shabiul for help tongue.gif (JKJK). According to martianunlimited suggestions previously, i already have a few 8-bit adders for you. Choose one to suit yr multi adder FP unit design, hehehe.
btw, anybody knows how to calculate the delay due to the increase of fan-in? Thanx
*
That depends on what gate you are using and whether it is a rise or fall delay. In a nand gate the rise delay is not affected, but the fall delay increases with every new input. The opposite is true for a NOR gate. It's not just the delays that are the problem though, it also affects signal integrity, which is why you don't normally see gates with large fan ins.
halo
post Nov 5 2005, 06:02 PM

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QUOTE(ikanayam @ Nov 5 2005, 01:44 AM)
Yes you can do it in one clock, you need to use a barrel shifter or eight 8-to-1 multiplexors. Both of which will consume a significant amount of hardware. You'll also need a subtractor to determine the difference in the exponents to give you the number of bits you have to shift.

*
hm...so for example, the result is something like 0.00001010, do u mean to count the number of zeros and then shift accordingly to make it 0.10100000?
ikanayam
post Nov 5 2005, 06:12 PM

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QUOTE(halo @ Nov 5 2005, 05:02 AM)
hm...so for example, the result is something like 0.00001010, do u mean to count the number of zeros and then shift accordingly to make it 0.10100000?
*
Yeah sorry i was thinking about the exponent alignment before FADD/FSUB when i mentioned the subtractor. For alignment after add/sub then yeah you can use a counter to determine how many bits to shift.

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