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Groups > comp.arch.embedded > #26779
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: MCU mimicking a SPI flash slave |
| Date | 2017-06-15 10:02 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <ohtena$7s5$1@dont-email.me> (permalink) |
| References | <ohrsl0$1i36$1@gioia.aioe.org> <ohtbt5$vh5$1@dont-email.me> <9Eq0B.74561$7A4.41458@fx19.am4> |
On 15/06/17 09:25, Tom Gardner wrote: > On 15/06/17 08:14, David Brown wrote: >> On 14/06/17 19:44, John Speth wrote: >>> Hi folks- >>> >>> I'm hoping to tap into your various experiences to see if what I'm >>> thinking is practical. >>> >>> Our customer has a device into which a Datakey is plugged to extract >>> data stored in the device. The Datakey is a really just a trade name >>> for a SPI flash with ergonomic features that resemble a real key (see >>> datakey.com). Our customer would like to replace the Datakey with a new >>> design that will transmit the data wirelessly instead of storing it to >>> the Datakey SPI flash. >>> >>> We're proposing a design based on an MCU which will appear as a SPI >>> slave flash device, store the data pumped to it from the customer's >>> device, and forward it wirelessly. I'm wondering if it's practical to >>> accomplish it. The firmware would have to be totally responsive >>> temporally and in data content. That sounds like a tough hill to climb >>> that requires getting the interface just right, nearly perfect. I see a >>> lot of pitfalls that could make the effort a dead end. >>> >>> Does anybody have any success or failure stories to relate that would >>> help us gauge the feasibility of the proposed design? >>> >>> Thanks - John Speth >> >> If you make sure you have a MCU with good slave SPI support and DMA, >> then the actual SPI transfers should not be an issue (assuming a sane >> SPI clock speed). The cpu would then not be involved in the >> back-to-back SPI moves at all. Pretty much any Cortex M3/4 device >> should cope fine. >> >> The key challenge is how to deal with the commands - the bits that need >> some processing. That will probably mean fast response to the first few >> incoming SPI bytes via an interrupt function. Your requirements here >> will depend on the protocol, the clock speed, the processing time >> required, etc. >> >> Write-style SPI commands are no problem - just buffer up the SPI command >> and data with DMA as it comes in. It's the read-style ones that are the >> killer. For very fast SPI interfaces, it is not uncommon that with a >> read command, the first byte returned is a dummy byte - that gives you >> the time to fill your DMA buffer with the real data for the reply. But >> not all SPI protocols use that, and they might have some reads that need >> immediate response. If you can get that under control, the rest should >> be (relatively) easy. >> >> If you can't build this from a normal microcontroller because you need >> too fast response, your options are FPGA (either as an assist to a >> microcontroller, or with a processor in the FPGA) or perhaps an XMOS >> microcontroller. XMOS programming is a bit different from normal >> microcontroller programming, but it will handle tasks like this easily. > > I'll just say that I find XMOS programming to be *very* > easy compared to C+RTOS -- doubly so for a hardware engineer. > > The "RTOS" is in hardware => very low API learning curve :) > XMOS programming is very easy for some things, but hard for other things. In particular, there is a limit to the scalability. It starts off easy splitting your work into lots of parallel tasks, putting them each in threads, and everything is fine - until you run out of hardware threads. Then you end up destroying your structure to get a several logically parallel tasks running in the same hardware thread, or running a software RTOS in one hardware thread. And when you have your multiple high-speed interfaces working, you find you don't have enough ram left for buffers. XMOS devices can be a lot of fun, and I would enjoy working with them again. For some tasks, they are an ideal solution (like for this one), once you have learned to use them. But not everything is easy with them, and you have to think in a somewhat different way. > The programming model (CSP) is *very* simple and also > comprehensive. It was invented in the 70s, and has stood > the test of time. Yes, CSP is a great tool. I was taught it by some of the folks behind it. (Tony Hoare himself was head of the department, but I didn't have him as a lecturer.)
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MCU mimicking a SPI flash slave John Speth <johnspeth@yahoo.com> - 2017-06-14 10:44 -0700
Re: MCU mimicking a SPI flash slave Don Y <blockedofcourse@foo.invalid> - 2017-06-14 16:30 -0700
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-14 21:54 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 08:01 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 12:13 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 18:01 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 16:52 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 23:37 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 18:15 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-16 09:25 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-16 13:52 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-18 22:56 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 00:21 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 09:02 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 08:36 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 14:47 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 09:23 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 15:34 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 00:16 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 09:49 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 22:44 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 12:10 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 12:40 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 18:19 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 14:34 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 21:41 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 17:14 -0400
Re: MCU mimicking a SPI flash slave edward.ming.lee@gmail.com - 2017-06-21 13:54 -0700
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 23:33 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 23:12 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-16 07:05 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-16 02:27 -0400
Re: MCU mimicking a SPI flash slave Tim Wescott <seemywebsite@myfooter.really> - 2017-06-14 23:17 -0500
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 08:03 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 09:14 +0200
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 08:25 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 10:02 +0200
Re: MCU mimicking a SPI flash slave Reinhardt Behm <rbehm@hushmail.com> - 2017-06-15 16:25 +0800
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 10:32 +0200
Re: MCU mimicking a SPI flash slave Reinhardt Behm <rbehm@hushmail.com> - 2017-06-15 21:48 +0800
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 10:09 +0100
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 09:41 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 13:04 +0200
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 12:31 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 14:20 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 17:46 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-16 13:21 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-16 13:55 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-16 16:34 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-16 15:40 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 00:47 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-21 15:47 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 19:15 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-21 15:50 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 19:16 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-21 18:00 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-22 11:24 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 12:12 -0400
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-16 14:22 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 03:15 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 00:54 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 10:30 +0200
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-19 12:54 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 13:49 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 09:28 -0400
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 09:19 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 16:23 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 23:57 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 12:36 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 08:20 -0400
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-19 14:44 +0000
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-19 21:39 +0200
Re: MCU mimicking a SPI flash slave Cecil Bayona <cbayona@cbayona.com> - 2017-06-19 14:59 -0500
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-20 09:25 +0200
Re: MCU mimicking a SPI flash slave Cecil Bayona <cbayona@cbayona.com> - 2017-06-20 11:50 -0500
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-20 12:37 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 22:59 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 00:12 -0400
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 10:25 +0300
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 10:44 +0200
Re: MCU mimicking a SPI flash slave dp <dp@tgi-sci.com> - 2017-06-20 02:36 -0700
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 11:25 +0100
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 13:49 +0300
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 12:54 +0100
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 16:09 +0300
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 15:24 +0100
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 17:46 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 22:28 +0200
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 00:58 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 13:08 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 16:28 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 12:58 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 12:57 +0200
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 14:19 +0300
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 16:19 +0200
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-20 12:12 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 16:48 +0200
Re: MCU mimicking a SPI flash slave Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2017-06-20 21:16 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 23:15 +0200
Re: MCU mimicking a SPI flash slave Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2017-06-21 07:30 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 12:54 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 19:29 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 15:05 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 21:34 +0100
Re: MCU mimicking a SPI flash slave "Elizabeth D. Rather" <erather@forth.com> - 2017-06-21 18:04 -1000
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-22 10:26 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 11:56 -0400
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-22 09:20 +0000
Re: MCU mimicking a SPI flash slave Wasell <from_usenet@wasell.eu> - 2017-06-22 14:02 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 11:59 -0400
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 11:58 -0400
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-22 08:19 +0000
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-19 09:53 +0100
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 10:16 +0100
Re: MCU mimicking a SPI flash slave John Speth <johnspeth@yahoo.com> - 2017-06-15 13:56 -0700
Re: MCU mimicking a SPI flash slave Don Y <blockedofcourse@foo.invalid> - 2017-06-15 14:41 -0700
Re: MCU mimicking a SPI flash slave John Speth <johnspeth@yahoo.com> - 2017-06-15 15:08 -0700
Re: MCU mimicking a SPI flash slave Don Y <blockedofcourse@foo.invalid> - 2017-06-16 11:34 -0700
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 18:20 -0400
Re: MCU mimicking a SPI flash slave edward.ming.lee@gmail.com - 2017-06-21 07:58 -0700
Re: MCU mimicking a SPI flash slave Walter Banks <walter@bytecraft.com> - 2017-06-19 12:23 -0400
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