Friday, 30 September 2011

Quartus TimeQuest work flow

As part of my long-lasting DDR2 IP block problems I've learned a little about the TimeQuest timing analyser. This is a program included with Altera's Quartus software which provides post-fit timing information about your design. Once the design is synthesised and the fitter has completed, you can run the TimeQuest tool to find out if your design meets the required set-up and hold timings. This is particularly useful/necessary for high speed circuits such as a DDRAM controller.

The TimeQuest tool is not intuitive. It is very powerful and mostly driven by Tickle scripts so I've outlined the design flow which I've come to learn over the past few days.

  1. Compile your design
  2. Launch the TimeQuest Analyser
  3. Create the Timing Netlist - at this step you can specify the speed grade and the temperature model
  4. Read the sdc file, this is the Tickle file containing the design constraints for your design. This may be generated by an IP block or you may have to create this file for your design. It will typically describe the clocks and derived clocks within your project
  5. Update the timing netlist. This step is Really important. I didn't realize this and as a result I found that my timing reports from the compilation stage disagreed with those produced in the TimeQuest analyser
  6. The final step is to source your timing report tickle script. This will present the setup/hold times for your design
If you don't perform step 5, updating the timing netlist, it is possible to find that the timing report produced as part of the compilation stage drastically disagrees with that produced in the TimeQuest analyser - very confusing.

Hopefully this will help anyone else struggling to verify the timing of their design.

Misleading Quartus Messages

For the last few weeks I've been struggling to get a closed source IP block from Altera to work. The block is a DDR2 controller for the Cyclone IV range. As part of my debugging I scrutinised all of the Quartus Analysis & Synthesis info and warning messages to try to get to the bottom of the problem (which is still unresolved). One message which stood out was the following:

Info: Instantiated megafunction "Ddr2RamController... with the following parameter:

      Info: Parameter "intended_device_family" = "Cyclone III"


Info: Instantiated megafunction "Ddr2RamController... with the following parameter:

      Info: Parameter "intended_device_family" = "Cyclone IV E" 
The compiler appears to instantiate some of the Megafunctions for the Cylcone III (which is different from the target device) and some for the Cyclone IV.

I subsequently highlighted this in a service request to Altera.

The official response from Altera is that this is the correct behaviour - despite being incredibly misleading. It turns out that the intended_device_family parameter is only used for simulation purposes, so the fact that it doesn't match the target device is irrelevant. Furthermore the altera docs (PDF page 55) does not allow for this parameter to be set to "Cylcone IV" - presumably, the IP block should behave identically in the Cyclone IV as it does in the earlier Cyclone III.

The result for me is that I'm still no closer to solving my DDRAM issues.

Hopefully this information will prove helpful to others struggling with misleading Quartus info/warning messages.

I originally posted a query about this in the Altera Forums to no avail:

Friday, 23 September 2011

Big Dog

A friend at work informed me of this US DARPA funded project called Big Dog. Watch the video of this robotic dog in action:

It is made by a US company called Boston Dynamics and they have published some slides and a technical paper about the different technologies and the use of compliant materials within the robot. I'd hate to think what the R&D costs of something this advanced would be. The Big Dog project website has links to the aforementioned presentation and technical paper. My favourite part of the video is when they kick Big Dog on the ice and it stumbles briefly before recovering. The slow motion jumping sequence is very impressive too!

Sunday, 18 September 2011

Holiday themed quiz

As part of our Canadian Thanksgiving celebrations we wrote a holiday themed quiz. Topics range from bizarre holiday customs through to holiday foods and films. The questions, and answers, can be downloaded here:

Holiday Questions

Holiday Answers

If you liked this you may also like:
  1. Canadian Quiz
  2. Thanksgiving Quiz Latex Template
  3. Pork Timing Diagram

Pork Timing Diagram

In preparation for a big Canadian thanksgiving dinner I prepared an ever so slightly nerdy timing diagram for cooking all the ingredients. I started off with the intention of a drawing a Gantt chart but several weeks of staring at DDR2 ram data sheets must have had an effect! The result was remarkably clear and the food turned out O.K so I'd call that a success!

Sunday, 11 September 2011

PDF Forms are Evil

I have to fill out some government forms which are all interactive PDF forms. Some of them even have the ability to save the form data deliberately disabled:

I cannot believe someone at Adobe thought this a good idea. I don't have a printer, so it means printing the stupid form to a postscript file! This doesn't smell like progress to me?

PDF forms are bad for other reasons too. They only seem to work properly with Adobe's PDF reader, so fat chance of using evince for linux or any other open source reader. Even after installing Adobe Reader for linux (shudders) the form is so unusable that you really have to question what the point of them is?

So in conclusion PDF forms are evil.

Saturday, 10 September 2011

A long weekend in Copenhagen

Copenhagen is a beautiful city and Danes are lovely people.

We recently spent the British August bank holiday in Copenhagen. Arriving early on the Friday morning after an uncomfortable Easyjet flight from Stansted we disembarked in glorious sunshine. Copenhagen airport is, like the rest of Copenhagen, beautifully designed, terrifically efficient (average time through security: 6 minutes) and welcoming. The newly built and still expanding metro service (which incidentally is suicide proof!) takes you straight from the terminal to the city centre in under 15 minutes and for not many Kroner. And from the city centre just about everything is within walking distance.

I'm no travel writer so here is a photo illustrated list of my prevailing thoughts and impressions of this magnificent city:

Copenhagen has a lot of parks and public gardens. You can spend a day just walking around parks if you wanted to. Locals seem to use them too. When the weather was good we saw Danes pitched in parks with crates of Carlsberg/Tuborg. Below is the most beautiful of all the parks, the Botanic Gardens:

From Copenhagen, Summer 2011

Danes do design. The state museum for modern design is a good example of this. I just wish my photography could do it justice:

From Copenhagen, Summer 2011

Even the children's play area is stylish and 'designed':

From Copenhagen, Summer 2011

Herons are a common site in the many parks and gardens. So much so there are statues of them dotted around the city:

From Copenhagen, Summer 2011

These terracotta buildings used to be army barracks but they seem to be domestic dwellings nowadays. I thought they looked stunning and enjoyed photographing them:

From Copenhagen, Summer 2011

From Copenhagen, Summer 2011

This windmill resides at the centre of an active fort, surrounded by a star-shaped moat:

From Copenhagen, Summer 2011

There is a _lot_ of graffiti in Copenhagen, this was one of the less permanent examples:

From Copenhagen, Summer 2011

Danes love their statues. Below is the famous Little Mermaid statue, a frequent victim of political activists. Below that is a statue we found en route which we mistook for the little mermaid. I'm divided as to which one I prefer:

From Copenhagen, Summer 2011

From Copenhagen, Summer 2011

We came across some crazy Danes. Here are some of them:

From Copenhagen, Summer 2011

From Copenhagen, Summer 2011

From Copenhagen, Summer 2011

Just about every famous Danish person in history was called Christian. Here is the city's much loved Hans Christian Anderson, children's author and figurehead for the city:

From Copenhagen, Summer 2011

Copenhagen is a city of canals. This one completely separated the state offices from the mainland. It was frequently circumnavigated by tourist barges not much smaller than the archways of the many bridges that cross it.

From Copenhagen, Summer 2011

From Copenhagen, Summer 2011

Back to more striking architecture and this is the new university library. Its like a glass battleship beached along the canal. Inside it has expansive concrete balconies and stairways at inconvenient angles, curvy passageways and a pretty reasonable cafe.

From Copenhagen, Summer 2011

From Copenhagen, Summer 2011

Christiania is an odd place. It is a self ruling community established in the seventies at a disused military base. It is now a haven for soft drug users, hippies and graffiti artists seeking something approaching immunity from the law. It is a surprisingly popular tourist destination. You are prohibited from running and taking photographs - both activities 'make people nervous'. Below is the entrance to this place.

From Copenhagen, Summer 2011

If you want a beer in Copenhagen you have a choice of Carlsberg or Tuborg. Both are now brewed by Carlsberg brewery and it could be argued are indistinguishable. Drinking out is not cheap in Copenhagen. Even though the brewery is a stone throw from the centre. We took a S-train out of the city to visit it. There is a quaint museum charting the history of brewing in Denmark and an impressive, world record breaking, collection of bottled beer.

From Copenhagen, Summer 2011

From Copenhagen, Summer 2011

As part of the preparations for our visit I compiled a Google map with markers of all the places to visit. Since I don't have a camera with geo-tagging capabilities (yet) I've embedded the map below so I can remember where we went and what we saw (and photographed):

View Copenhagen Trip Aug '11 in a larger map

All my photos from this trip are in this Picasa web album:

99% Invisible

Its not often that I find a blog which interests me so much that I want to link to it. 99% Invisible is one of them.

It is a collection of well produced, succinct podcasts about design, architecture and engineering. Some of my favourite episodes cover topics such as:

Redesigning the bank statement

Samuel Plimsol's eponymous line

The Great Pyramids