Yahoo Groups archive
Thread
2005-08-05 by fcervone1
Hi Folks, Do you have any idea on what's the maximum performance for LPC2210 @ 60MHz clock we can reach considering : 1. Accessing one 8-bit external flash code memory bus? 2. Accessing 16-bit external flash code memory bus? Fabio
2005-08-05 by lpc2100_fan
Hi Fabio, that depends on a few factors: 1. access time of the Flash 2. ARM mode or Thumb mode 3. Between 8-bit and 16-bit bus almost exactly the factor of 2 in performance out of Flash. 1. The access time will determine the number of waitstates. As a rule of thumb ;-) you best performance to power ratio will be at the max speed for 0 WS Flash. Example: a 50ns Flash provide roughly a 20 MHz 0 WS access option. If you run at 25 MHz and need a wait state you will consume more power and be slower. 2. In this case use Thumb mode whenever you can while working from the Flash, it will run faster because the instruction fetch is the bottleneck. Proposal: If you need more performance, I would HIGHLY recommend to use the LPC2220 instead of the LPC2210. Not only is the 2220 specified for a max. of 75 MHz, much more important it has 64K SRAM instead of 16K. This enables you to load performance critical parts of your code, e.g. interrupt service routines or DSP algorithms into the SRAM, executing 0WS up to 75 MHz. In this case you might want to use ARM mode because there is no bottleneck for fetching and ARM mode will be approx. 30% faster than Thumb mode. To summarize this, the LPC2220 is pin compatible to the LPC2210 but offers 4x the SRAM and this SRAM can be used for performance upgrade. Just a wild guess, between 16-bit bus executing from external 50 ns Flash in Thumb mode and 75 MHz executing in ARM mode from internal SRAM is probably a performance increase by a FACTOR of 4x to 5x!! Convinced ;-) The tough part, the LPC2210 is much easier to get than the LPC2220, which is kind of new but afaik not much higher price. Cheers, Bob --- In lpc2000@yahoogroups.com, "fcervone1" <fcervone1@y...> wrote:
> Hi Folks, > > Do you have any idea on what's the maximum performance for LPC2210 @ > 60MHz clock we can reach considering : > > 1. Accessing one 8-bit external flash code memory bus? > 2. Accessing 16-bit external flash code memory bus? > > Fabio
2005-08-08 by fcervone1
Bob, Tks for your reply. I am really convinced with your answer. For instance, if I use a Flash Memory 90nsec time access and I am running @75MHz LPC2220 do you know how many mips we can get from the CPU ? How do I calculate the performance with a introducing of wait states ? Tks in advance, Fabio --- In lpc2000@yahoogroups.com, "lpc2100_fan" <lpc2100_fan@y...> wrote: > Hi Fabio, > > that depends on a few factors: > 1. access time of the Flash > 2. ARM mode or Thumb mode > 3. Between 8-bit and 16-bit bus almost exactly the factor of 2 in > performance out of Flash. > > 1. The access time will determine the number of waitstates. As a rule > of thumb ;-) you best performance to power ratio will be at the max > speed for 0 WS Flash. Example: a 50ns Flash provide roughly a 20 MHz > 0 WS access option. If you run at 25 MHz and need a wait state you > will consume more power and be slower. > > 2. In this case use Thumb mode whenever you can while working from the > Flash, it will run faster because the instruction fetch is the bottleneck. > > Proposal: If you need more performance, I would HIGHLY recommend to > use the LPC2220 instead of the LPC2210. Not only is the 2220 specified > for a max. of 75 MHz, much more important it has 64K SRAM instead of > 16K. This enables you to load performance critical parts of your > code, e.g. interrupt service routines or DSP algorithms into the SRAM, > executing 0WS up to 75 MHz. In this case you might want to use ARM > mode because there is no bottleneck for fetching and ARM mode will be > approx. 30% faster than Thumb mode. > > To summarize this, the LPC2220 is pin compatible to the LPC2210 but > offers 4x the SRAM and this SRAM can be used for performance upgrade. > > Just a wild guess, between 16-bit bus executing from external 50 ns > Flash in Thumb mode and 75 MHz executing in ARM mode from internal > SRAM is probably a performance increase by a FACTOR of 4x to 5x!! > > Convinced ;-) > > The tough part, the LPC2210 is much easier to get than the LPC2220, > which is kind of new but afaik not much higher price. > > Cheers, Bob > > > --- In lpc2000@yahoogroups.com, "fcervone1" <fcervone1@y...> wrote: > > Hi Folks, > > > > Do you have any idea on what's the maximum performance for LPC2210 @
> > 60MHz clock we can reach considering : > > > > 1. Accessing one 8-bit external flash code memory bus? > > 2. Accessing 16-bit external flash code memory bus? > > > > Fabio
2005-08-08 by lpc2100_fan
Hi Fabio, honestly I do not like "MIPS" but for the lag of a better most simple measure, running directly from a 90 ns external Flash 16-bit wide in Thumb mode will probably get you between 10 and 15 "Thumb MIPS" even at 75 MHz. By the way if you run at 11 MHz (assuming 0 WS), you will only see a marginal difference in performance but your timers will be slower and there is no option of fast execution from SRAM. Power will be very low though! Running from internal SRAM at 75 MHz will provide between 65 and 70 ARM MIPS. Keep in mind that a "Thumb MIPS" is less than an "ARM MIPS" because it takes approx. 10 Thumb instructions to perform the same function as 7 ARM instructions. If your application follows the typical application, you will execute more than 90% of the time out of less than 10% of the code area. If the code that is in need for speed executes out of the SRAM, you will get close to the max. performance of your system. Cheers, Bob --- In lpc2000@yahoogroups.com, "fcervone1" <fcervone1@y...> wrote:
> Bob, > > Tks for your reply. I am really convinced with your answer. > > For instance, if I use a Flash Memory 90nsec time access and I am > running @75MHz LPC2220 do you know how many mips we can get from the > CPU ? > How do I calculate the performance with a introducing of wait states ? > > Tks in advance, Fabio > > > --- In lpc2000@yahoogroups.com, "lpc2100_fan" <lpc2100_fan@y...> > wrote: > > Hi Fabio, > > > > that depends on a few factors: > > 1. access time of the Flash > > 2. ARM mode or Thumb mode > > 3. Between 8-bit and 16-bit bus almost exactly the factor of 2 in > > performance out of Flash. > > > > 1. The access time will determine the number of waitstates. As a > rule > > of thumb ;-) you best performance to power ratio will be at the max > > speed for 0 WS Flash. Example: a 50ns Flash provide roughly a 20 > MHz > > 0 WS access option. If you run at 25 MHz and need a wait state you > > will consume more power and be slower. > > > > 2. In this case use Thumb mode whenever you can while working from > the > > Flash, it will run faster because the instruction fetch is the > bottleneck. > > > > Proposal: If you need more performance, I would HIGHLY recommend to > > use the LPC2220 instead of the LPC2210. Not only is the 2220 > specified > > for a max. of 75 MHz, much more important it has 64K SRAM instead of > > 16K. This enables you to load performance critical parts of your > > code, e.g. interrupt service routines or DSP algorithms into the > SRAM, > > executing 0WS up to 75 MHz. In this case you might want to use ARM > > mode because there is no bottleneck for fetching and ARM mode will > be > > approx. 30% faster than Thumb mode. > > > > To summarize this, the LPC2220 is pin compatible to the LPC2210 but > > offers 4x the SRAM and this SRAM can be used for performance > upgrade. > > > > Just a wild guess, between 16-bit bus executing from external 50 ns > > Flash in Thumb mode and 75 MHz executing in ARM mode from internal > > SRAM is probably a performance increase by a FACTOR of 4x to 5x!! > > > > Convinced ;-) > > > > The tough part, the LPC2210 is much easier to get than the LPC2220, > > which is kind of new but afaik not much higher price. > > > > Cheers, Bob > > > > > > --- In lpc2000@yahoogroups.com, "fcervone1" <fcervone1@y...> wrote: > > > Hi Folks, > > > > > > Do you have any idea on what's the maximum performance for > LPC2210 @ > > > 60MHz clock we can reach considering : > > > > > > 1. Accessing one 8-bit external flash code memory bus? > > > 2. Accessing 16-bit external flash code memory bus? > > > > > > Fabio