Breaking News
Comments
Oldest First | Newest First | Threaded View
<<   <   Page 3 / 3
DrFPGA
User Rank
Author
Re: math links
DrFPGA   12/9/2013 11:02:27 AM
NO RATINGS
Remember when we had to do many of the FPGA tricks by hand? Register retiming, one hot state machines, if then else to mux conversions? Now the synthesis tools do all this for us. Hopefully tricks like the multiply by a constant will get folded in too. Just depends on how common the need is for these tricks I guess.

Maybe there should be a 'list' of tricks that users suggest would be good to put into synthesis tools. Perhaps via a discussion thread on Programmable Logic Design Line?

betajet
User Rank
Author
Know the limitations of your tools
betajet   12/9/2013 2:20:02 PM
NO RATINGS
I remember the first time I synthesized an FPGA design for a real product.  The synthesizer automatically came up with a one-hot state machine coding.  Everything simulated fine.   Unfortunately, this particular design did not have a well-formed clock when connecting or disconnecting the input signal, which would cause it to lose the one-hot code occasionally when reconnecting.  Switching to a manual state coding that automatically recovered from bad states fixed the problem -- and saved logic cells in this case.

Lesson 1:  Don't trust automatic state assignment.  Some synthesizers make it hard to turn off automatic state assignment, but it's worth the effort.

Lesson 2:  Don't trust simulation.  It only simulates theoretical models, not the real world.

Lessons 1+2 combined and generalized:  Know the limitations of your tools.

DrFPGA
User Rank
Author
Re: Know the limitations of your tools
DrFPGA   12/9/2013 2:37:47 PM
NO RATINGS
Very important point and one difficult to do in practice. How many tools actually document (in detail) what the tool will do or not do. I find I need to do small example designs and look over th output of the place and route tool to figure out what is going on. Widh the vendors did this for me!

Anyone else have tools with detailed enough docs that they can tell ahead of time what is being done?

paragdighe
User Rank
Author
its fixed point math
paragdighe   12/10/2013 4:45:31 AM
NO RATINGS
1 saves
here's why it works: x/10=x*0.1={2^16*x*0.1}/2^16={x*2^16*0.1}/2^16 =x*1999H/2^16 

<<   <   Page 3 / 3


Radio
LATEST ARCHIVED BROADCAST

What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.

Brought to you by:

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Most Recent Comments
Like Us on Facebook
Special Video Section
With design sizes expected to increase by 5X through 2020, ...
01:48
Linear Technology’s LT8330 and LT8331, two Low Quiescent ...
The quality and reliability of Mill-Max's two-piece ...
LED lighting is an important feature in today’s and future ...
05:27
The LT8602 has two high voltage buck regulators with an ...
05:18
Silego Technology’s highly versatile Mixed-signal GreenPAK ...
The quality and reliability of Mill-Max's two-piece ...
01:34
Why the multicopter? It has every thing in it. 58 of ...
Security is important in all parts of the IoT chain, ...
Infineon explains their philosophy and why the multicopter ...
The LTC4282 Hot SwapTM controller allows a board to be ...
This video highlights the Zynq® UltraScale+™ MPSoC, and sho...
Homeowners may soon be able to store the energy generated ...
The LTC®6363 is a low power, low noise, fully differential ...
See the Virtex® UltraScale+™ FPGA with 32.75G backplane ...
Vincent Ching, applications engineer at Avago Technologies, ...
The LT®6375 is a unity-gain difference amplifier which ...
The LTC®4015 is a complete synchronous buck controller/ ...
10:35
The LTC®2983 measures a wide variety of temperature sensors ...
The LTC®3886 is a dual PolyPhase DC/DC synchronous ...