Breaking The Three Laws

 

Prototyping Low Power Functions Using UPF

Regardless of the market segment your product targets you are being required to build it with the lowest power operation to either compete, differentiate or just be more green. This week I ran into a customer who unfortunately had to re-spin their chip due to a low power mode of operation issue. The software was able to put the chip into a low power mode but due to a bug, they were unable to get the chip out of the low power mode cleanly without a system reset. This customer wanted to better verify the low power modes before tape-out this time around.

UPF (IEEE 1801-2009 ― Unified Power Format) is the industry standard for design and verification of low power integrated circuits. As noted above, these low power modes are a mix of hardware capabilities under software control and to verify the operation the two must be run together which poses a challenge for the verification and software engineers. Physical, FPGA-based prototyping would seem like the logical solution to this problem as you are running a high performance, cycle accurate model of the design against the real software. But there is a problem, FPGA’s are not ASIC’s .

FPGA’s are volatile

  • No power islands or partial turn off
  • Configuration file loaded from external memory

Multi-voltage cells are not present

  • Only user configurable cells

A single power and single ground

  • VCC, GND for user mapping

Click picture for full size render.

Low power intent view in ASIC

But will you cannot test the exact power domain capabilities of your design there are still many capabilities which can be modeled in the Physical Prototype which will result in higher test coverage of the designs low power capabilities. To make this process easy the Synopsys ProtoCompiler tool can read your UPF and implement a number of lower power capabilities as part of the HAPS physical prototype. This enables the software that controls these lower power modes to be more fully verified pre-silicon.

Some of the key low power capabilities which can be inferred directly from the UPF through the ProtoCompiler for HAPS flow are:-

Verify/validate logical of the islands and control manager

  • Isolation behavior
  • Retention behavior
  • Power Management Unit (PMU) connections and control

Click picture for full size render

Low power modes modeled through ProtoCompiler for HAPS

With this low power logic modeled in HAPS the design’s low power modes can be more extensively tested. The isolation and retention behavior is a mix of hardware functions controlled by software which can now both be tested together. ProtoCompiler’s implementation of the UPF directives modeled in the HAPS systems the designs inferred low power modes enables the hardware and software engineers to expand the low power mode verification resulting in lower rick risk of post-silicon issues.

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I’m taking a personal break over this holiday period so no blog for a couple of weeks. I would hope that no one is around or bored enough to want to read this blog over the break period anyway so no one will really notice.

I grew a beard for the winter break, (see below) not because I’m hip and trendy but because I like to ski/snowboard/mountain climb during the break and a beard protects your face from the wind. I’ll shave it off in January and then post a comparison picture. I like a beard for the technical reasons listed but I really don’t think it suits me.

Mick grew a beard

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