Large scale data logging - RS232 to USB disk

M

matherp

Senior Member
I've Just purchased a UART USB Flash Disk W/R Controller from Sure Electronics on ebay. This is a great little device that does all the interfacing to either an SD disk or USB disk depending on which version you buy. I've tested it on a 8Gb microSD in a USB adapter.

The RS232 command interface is slightly quirky but very easy to use (DOS like). To write a log file "FOPEN file.nam", then "FWRITE" to start logging, everything then sent is logged to the file until you send the STOPFLAG which by default is "+++++"
Then you need to close the file with FCLOSE

The device supports FAT16 or FAT32 and the files are then easy to read on a PC. I'm formatting them as .CSV so they can be read directly in excel

Hope this is of use

Best Regards

Peter
 
G

GreenLeader

Senior Member
Looks interesting. Can you post some code to show how it works?
What happens if you don't close the file? - eg if you are busy logging and you lose power - do you lose the whole file?
What are the advantages of this over the picaxe Vdrive2?
 
L

lewisg

Senior Member
This looks like a great project but unless you want to spend time developing a logger I don't see an advantage over OpenLog. Same for vDisk...

To log using OpenLog the PICAXE code is minimal:
Code: 
pause 100                                                         'let things "settle"
high C.1                                                          'init logger pin
pause 100

start:
  serout C.1, t2400,("time", 9, "rawCur", 9, "rawVolt", 13,10)    'make a nice header

do

  'do stuff
  
  serout C.1, t2400,(#time, 9, #rawCur, 9, #rawvolt, 13,10)       'log data

loop
The code above makes a nice log like this on a SD card:
Code: 
time	rawCur	rawVolt
5	510	809
10	509	858
15	509	268
20	509	86
25	509	682
30	509	890
35	509	927
40	509	934
45	509	935
The preparation of a FAT16 or FAT32 SD card (SDHD up to 16G) is putting a file named CONFIG.TXT on the card containing this line:
Code: 
2400,26,3,0
Micro card units are $25 at SparkFun.

Full size card units are $25 at seeedstudio.

I have yet to corrupt data with power cycles, removing the card (from a running project while the write data LED is off) or with flakey connections. OpenLog just works so you can get on with your task. I can't imagine any easier way to log a LOT of data. 26 days of the example above made a 3.3MB file.

Whatever you do, don't use CSV files. They are the work of the devil. Use something human readable like tab separated or columnar tables using spaces so a quick scroll can verify correct data placement. I import a LOT of data every year from many sources and CSV files cause lots of headaches and rework.
 
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M

MFB

Senior Member
I'll second that for the OpenLog. Low cost and VERY easy to use with the PICAXE. Its been totally reliable when used on my RC aircraft logger.
 
G

GreenLeader

Senior Member
It does look really good. Might get one to try out. How fast have you guys run it? I think I would need to run at 115200 baud for my project.
 
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