A question about SD cards

twentytwoo

New Member
I've been looking around this forum a lot about various ways of integrating SD cards in their projects, I noticed two popular ways of doing this.
One using the ALFAT SD module by GHI and the other via SparkFuns OpenLog.

My situation is a little easier in that I only require reading data from the SD card, I know a lot of people on this forum have dabbled in FAT file systems and had a lot of trouble.

Essentially all I want to do is load some hex values onto an SD card via computer, insert this SD card into either of the above modules, and then get this data and output it onto one of the PICAXE's ports.

I've done quite a bit of work with PICAXE, but only in the AQA Assembler (PIC 28x1), so I'm here asking about anyone who's had any success with either of these modules.

Thanks.
 
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premelec

Senior Member
Welcome to this forum - I'm not sure why you aren't getting any replies... I did notice quite a number of comments on Openlog using the advanced forum search tool - available upper right side of screen while you are logged in. There are some refs to reading the cards - do you have a problem with doing something with what you have read?
 

Jeremy Harris

Senior Member
I've used both the Sparkfun OpenLog and the Seeed Studio SDLogger modules, and they are easy enough to use to just read a file from a µSD or SD card, respectively. The OpenLog is slightly less fussy with command syntax and timing than the SDLogger, I found, but I suspect this may be down to the latency in the Picaxe software serial ports (I've not tried using a hardware serial port).

I did document some stuff here using an OpenLog with a Picaxe, that may give you some clues as to how to get a Picaxe to work with an OpenLog:

http://www.picaxeforum.co.uk/showthread.php?20563-Data-logging-to-a-microSD-card

http://www.picaxeforum.co.uk/showthread.php?20551-Environmental-uSD-card-data-logger

http://www.picaxeforum.co.uk/showthread.php?23893-Air-quality-monitor-and-logger
 

darb1972

Senior Member
Hello

I have read a number of Jeremy's extremely well written and documented threads on the OpenLog. Thank you for your work Jeremy. I have a number of projects where the logging of events/data would be extremely useful.

I believe there is a Sparkfun distributor here in Australia and although I don't mind spending the $20 + dollars + freight for each module, there are modules that "look the same" on eBay for around $8-00 delivered. I'm not sure if they are a ripoff of the Sparkfun original. Has anyone used these or is it just not worth the risk?

Here's an example;

http://www.ebay.com.au/itm/Micro-SD-Openlog-Serial-Data-Logger-Open-Source-Data-Recorder-ATmega328-Support-/302344627318?hash=item466524e476:g:ZMEAAOSwMvtZOoCC
 

darb1972

Senior Member
Thanks mikey.

I have read about FRAMs in the past. I think definitely a good alternative to a standard EEPROM. The attraction of the SD Card is not only the shear size of the available memory, but, also the fact that it can be easily removed for further data analysis.

I guess it depends on the project. At this stage I have a few ideas in mind where a removable SD Card approach would be handy. Other than that, I think it would be a great concept to toy with on the work bench. :eek: I love experimenting with new devices (when time permits). All I need do is win the lotto and quit my day job. A PICaxe based (winning) lotto number generator should be my highest priority project. :rolleyes:

I'm just not sure if buying one of the modules from ebay is worth the risk if it proves to be a dodgy ripoff. Unless someone can advise to the contrary, maybe to play it safe for my first one I'll order the original. I wouldn't want to get a dud and waste hours finding out the hard way.
 
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