Is ALFAT a solution for me?

File-System Hardware
1

Hi,

I have to build some Kind of data logger.
My sample Speed is 16kSPS and each sample consists of 27 Byte max.
Preferred Interface is SPI.

Solution 1.) Using the G400D as main processing unit to control the System (there is more to do than data logging) and get data via SPI from my ADC (ADS131E06 by TI), but NETMF didn#t implement DMA Transfers for SPI, so this solution is much to slow …

Solution2.) Writing a RLP to get the data in, ok, tedious work, much pitfalls ahead, programming skills since 1975, so this isn’t the Problem, but still lot of work. If I really get the data into RAM I have to save the data on some Kind of non volatile media, SD Card preferred, but the data Transfer from Memory to SD Card using NETMF seems to be much too slow, I am right? I Need about 400kByte a second.

Solution3.) Using ALFAT with SPI Interface and ‘L’ command and connect it to the G400D or whatever host System board via USB. As the ALFAT Manual told me, I can expect 750kByte writes to the slowest media via SPI, which is more than enough. Than I can activate the USB-PC link and Access the data from any Kind of embedded System which has a USB host Interface. I can use whatever OS there or using NetMF but now without any hurry. Between my data logging Events I have plenty of time to process the generated file(s) without any hurry.

Solution3a.) I Need some Kind of processing functionallity to control my ADC and related HW. Maybe it is possible to extend the Firmware of an ALFAT SoC to do this Job?
There is not so much work to do but ALFAT has to be a SPI master instead of a SPI slave device. This way I can read out my ADC and pump the data directly into a open file.
Workflow: Main System send some configuration Parameters and a file Name. After that a Hardware Signal ‘START’ is issued and the modified ALFAT starts checking the DRDY Signal (data ready) of the ADC and pumps data in the opened file. After ‘START’ goes low again, a ‘Close’ command will be executed on that file and we were happy.

Any ideas?

With best regads

Gerhard

2

@ Gerhard -

This is not an answer for your big question, just if you are going to use “L” command and USB High speed then 750KB/s should be fine.

just that, let say ALFAT can write 1MB/s, 100K can be not 100ms, but 1K completely does not take 1ms, longer. Writing a big chunk is faster than few bytes.

if there are few KB, almost accessing time will be at opening / closing the file. This can be take few ms, few hundred ms, depends on your media, and total files exist on the media.

just more information, hope to help you have more idea in your project.