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Looking for high speed USB memory stick or SDHC reading solution
Posted by mikeselectricstuff on 27 Jan, 2013 12:33 -
All I want to do is be able to read data from a file and throw it out of either multiple UARTS, fast SPIs or 8 bit parallel, into an FPGA at rates of 1-4Mbytes/sec continuous (i.e. need enough extra speed & RAM buffering to cover any filesystem latency).
I've used the PIC24F parts with USB host and SD, which work fine as far as they go but the fundamental speed of the interface is a limiting factor. (as well as, at least in the case of SD, inefficient code, but this is fairly easy to tweak for a 2-3x efficiency gain)
Does any one know of any MCU that satisfies the following :
USB 2.0 high speed or SDHC port, and working free example code to read from a memory device, which can be compiled with a free or low-cost toolchain. (Ideally IAR EWB kickstart edition)
Not BGA, and readily available in small qty (10s). Onboard Phy would be nice.
Not under Linux - just power up & go. It will not be doing anything else - just reading a file and streaming it out so don't want the baggage and learning curve of an OS
NXP LPC1800 looks a possibility with their nxpUSBlib library but not clear if their USB library supports hi-speed. This post indicates that there are some major performance issues at the moment
http://www.lpcware.com/content/forum/mass-storage-readwrite-performance-lpc18xx
At least non-BGA packages appear to be becoming more available now.
Bare metal code on a RasPi may be an option if I can get the data out somehow - maybe parallel via IO pins - not looked in detail yet - does anyone know if there is a file system avaialabe yet for bare-metal users?
This looked promising but speed is limited by the slow interface to the host, and the 4MBytes/sec speeds claimed turn out to only be useful for card-card copying.
http://www.ghielectronics.com/catalog/product/340
I think this is based on a ST ARM Cortex M3 chip.
If they had a way to, for example read USB and spit it out of the 4-bit SPI interface, under control of the UART port that could be ideal.
Something that can be got up & running easily with minimal learning curve is highest priority - parts cost not a major issue.
Just wondering if anyone else has looked into this before I start digging any further..
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Have you looked at Freescale's Kinetis series? At least some of the bigger parts claim to support all of SDHC, USB HS and external bus interfaces. Never used them myself, so can't comment on any of that.
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Maybe the the person is using the LPC1800 wrong. AFAIK the speed of the USB connection is set by a resistor to the data lines. If he got that wrong the USB connection is not hi-speed. And there are two ways of sending packets over a USB connection. One method is for messaging, the other for bulk data.
For your purpose you could probably use an USB to SPI chip like thise one http://www.ftdichip.com/Products/ICs/FT232H.htm to convert the data stream on the USB bus to an SPI interface. -
For your purpose you could probably use an USB to SPI chip like thise one http://www.ftdichip.com/Products/ICs/FT232H.htm to convert the data stream on the USB bus to an SPI interface.
Is this chip able to read file system on a usb device connected?
I believe Maxim has some ready to go SPI to USB mass storage chips. Don't know how fast it is.
Alexander. -
Maybe the the person is using the LPC1800 wrong. AFAIK the speed of the USB connection is set by a resistor to the data lines. If he got that wrong the USB connection is not hi-speed. And there are two ways of sending packets over a USB connection. One method is for messaging, the other for bulk data.
No - I need USB Host, not device.
For your purpose you could probably use an USB to SPI chip like thise one http://www.ftdichip.com/Products/ICs/FT232H.htm to convert the data stream on the USB bus to an SPI interface.
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The issue is not so much speed (once the basic interface is running High Speed) but something with a software solution that works & that I can tweak for my needs without having a huge learning curve for USB etc.
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How about the Vinculum chip from FTDI?
http://www.ftdichip.com/Products/ICs/VNC2.htm
It's a programmable USB-Host and available as DIP-Modules:
http://www.ftdichip.com/Products/Modules/DevelopmentModules.htm#V2DIP1
I have no experience with this product, but maybe it can do what you are looking for?
Martin
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I would go with the vinculum as well. It can even handle the filesystem. Look at vinculum 2 in special.
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Neither Vinculum support high-speed though. The FT313H does, but looks like you have to run the USB stack externally.
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I would go with the vinculum as well. It can even handle the filesystem. Look at vinculum 2 in special.
The VNC2 would be exactly what I need IF it were high speed, but it isn't. -
Something like the device bellow, or I got all wrong?
Nope. Not high speed and needs a SW stack on a seperate MCU.
http://tinyurl.com/aypqpaa
Alexander. -
What about the Chipkit Max32?
http://ww1.microchip.com/downloads/en/DeviceDoc/chipKIT%20Max32_rm.pdf
Just a stab in the dark.
David. -
What about the Chipkit Max32?
Doesn't support high-speed USB or SD cards. -
Have you looked at Freescale's Kinetis series? At least some of the bigger parts claim to support all of SDHC, USB HS and external bus interfaces. Never used them myself, so can't comment on any of that.
Unless you want to port the stack to GCC you will need Codewarrior for this BTW. -
Take a look at
http://www.digikey.com/product-detail/en/LPC4320FBD144,551/568-9449-ND/2840461
I solved this problem by having an fpga with custom SD controller do block DMA transfers to sdram. An external CPU woudl read the filesystem and find the longest span of contigous file sectors, then load the sector range in the FPGA where hardware dma was performed.
10mb/sec capped. -
What about the Chipkit Max32?
Not high speed. "USB 2.0 Full Speed" just means plain old USB.
http://ww1.microchip.com/downloads/en/DeviceDoc/chipKIT%20Max32_rm.pdf
Just a stab in the dark.
David. -
Take a look at
Was this SD in SPI mode or full 4-bit? Documentation on the latter appears scarce as you need to join the SD card club to get it.
http://www.digikey.com/product-detail/en/LPC4320FBD144,551/568-9449-ND/2840461
I solved this problem by having an fpga with custom SD controller do block DMA transfers to sdram. An external CPU woudl read the filesystem and find the longest span of contigous file sectors, then load the sector range in the FPGA where hardware dma was performed.
10mb/sec capped.
This may be a viable approach, even just doing it a sector at a time.
But it's frustrating that there are several MCUs out there that should be able to do it all, it just needs the software stack to be there.
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The SPI bus on an SD card what speed can offer?
Alexander. -
You can get ~2-3 mbyte/sec through SPI. But, there is sufficient info in the SD simplified spec to implement 4bit mode. I sat down with a printout of the spec and had it working in 3 days, only sticking point was the separate rolling crc16 on each data line, but here you goCode: [Select]
crc16_3 <= {crc16_3[14:0], 1'b0} ^ ((pin_dat_out[3] ^ crc16_3[15]) ? 16'h1021 : 16'h0);
crc16_2 <= {crc16_2[14:0], 1'b0} ^ ((pin_dat_out[2] ^ crc16_2[15]) ? 16'h1021 : 16'h0);
crc16_1 <= {crc16_1[14:0], 1'b0} ^ ((pin_dat_out[1] ^ crc16_1[15]) ? 16'h1021 : 16'h0);
crc16_0 <= {crc16_0[14:0], 1'b0} ^ ((pin_dat_out[0] ^ crc16_0[15]) ? 16'h1021 : 16'h0); -
The SPI bus on an SD card what speed can offer?
Not sure what the max speed is in single SPI mode , which is essentially MMC card emulation. The MMC spec says 20MHz - it could be that the more recent SD cards may inherit a bit more speed from the SD hardware.
Alexander.
The above post on FPGA gives me an idea of how I could get a lot more speed using my existing SD card code in simple SPI mode. I know when the filesystem library is reading data from my file (because I've already hacked the code a lot it to speed it up!) , so I could externally mux the SPI bus with a CPLD or FPGA so when I know the file data read is happening, the external logic clocks the card as fast as possible and catches the data, the PIC host being oblivious to the data transfer.
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The non GNU/Linux requirement is because you just don't want to fiddle with it?
Alexander. -
The SPI bus on an SD card what speed can offer?
Not sure what the max speed is in single SPI mode , which is essentially MMC card emulation. The MMC spec says 20MHz - it could be that the more recent SD cards may inherit a bit more speed from the SD hardware.
Alexander.
The above post on FPGA gives me an idea of how I could get a lot more speed using my existing SD card code in simple SPI mode. I know when the filesystem library is reading data from my file (because I've already hacked the code a lot it to speed it up!) , so I could externally mux the SPI bus with a CPLD or FPGA so when I know the file data read is happening, the external logic clocks the card as fast as possible and catches the data, the PIC host being oblivious to the data transfer.
Just to get things clear: you want to use a USB stick OR an SD-ish card to store a file and dump it into an FPGA?
If yes: Some microcontrollers in the LPC2000 series from NXP have a dedicated SDHC interface. It can do 4 bit transfers. With this FAT filesystem http://elm-chan.org/fsw/ff/00index_e.html you can have the SDHC part up & running real quick (it has drivers for the LPC2300). To transfer the data into the FPGA you can use SPI and DMA. IMHO SDHC is a much easier route than USB host.
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The non GNU/Linux requirement is because you just don't want to fiddle with it?
A few reasons - Mainly I don't want to learn Linux for what should be a simple job, I want it to start quickly on powerup, I need a guaranteed data flow rate, so can't have any unpredictable latency issues. I also don't want to have to burn unnecessary power/cycles on things that aren't needed.
Alexander. -
The non GNU/Linux requirement is because you just don't want to fiddle with it?
A few reasons - Mainly I don't want to learn Linux for what should be a simple job, I want it to start quickly on powerup, I need a guaranteed data flow rate, so can't have any unpredictable latency issues. I also don't want to have to burn unnecessary power/cycles on things that aren't needed.
Alexander.
Ohhh, that's easy! Just download the source code of the real time Linux kernel (Wind River Systems) play with it for couple of years to customize it and you are done!
Alexander.