Hello, First off I just wanted to give a massive thank you to the community, the elites of the forum, and those working at the Spark company especially those active on the forum! For the past couple months I’ve been posting frequently and receiving great support and direction, so I wanted to say th…

@UST , if I understand correctly, you have one non-connected Core doing data logging so you don’t get any code blocking when the cloud connection drops. You have have another Core which can suffer the block but when it reconnects, you want it to send the logged data that was not sent during the outa…

I sort of do, I already have a “heart beat” signal, showing the logging core when it needs to save into two different files. If things run smoothly it might work, but when the “wifidown” file gets two large, and both are opening files at once it might get sticky as you and @AndyW stated! So it seem…

@UST , here is a little Arduino SerialCommand library that allows you to really easily setup a serial command structure for the Logging Core. I ported this already if that interests you. :slight_smile:

Oh nice! That’s great, I’ll look into that ASAP, thank you @peekay123 :smiley:

Side note @peekay123 : What if I did it so that when WiFi was on, only one core talked to the SD card, and when WiFi is off the other talks. But they’ll never talk at the same time? Is this also a fix, before I go pouring time into the alternate avenue :stuck_out_tongue:

@UST , the SPI hardware in the Core is supposed to tri-state the SCK/MISO/MOSI lines when a byte has been transferred. However, the chip select line will not as it must be held high or low to control the slave device. So my hunch is you would need to add a pull-up to the SD CS line so that it never…

Glare on the CS lines is one basic problem, and really can’t be avoided by simple delays. Resist the temptation to spend cycles fixing this problem, only to run into ugly shared-filesystem problems… As I said, that way lies madness.

As I’m starting to realize just by trying to do simple work around. Again, I’ll look into another avenue that @peekay123 suggested and post here when I find an answer. EDIT: Going to be looking into I2C interface as @peekay123 described, the serial commands are neat but I want the communication be…

just to add more momentum to the current direction of “no don’t do that!” - FAT is not a concurrent access filesystem - even without the shared SPI bus issues, the file system would become corrupted very quickly. However, if you can interleave accesses to the filesystem, then it’s ok. But really u…

@mdma , the reason @UST wanted to use a second core was because of user code blocking when the cloud connection is lost. :smile:

Two Cores, One SD

Hardware

philipq January 7, 2015, 8:29pm 20

A comment on the “user code blocks” issue. An unofficial fix for this issue has been provided by @mummblepins. The issue and fix are discussed is in this thread:

Topic		Replies	Views
Semi-Automatic Mode Question General	38	9726	December 6, 2014
Core should keep running or be able to start even w/o Cloud access Firmware	56	9112	June 10, 2014
Micro SD card library Libraries	86	21247	August 14, 2014
MicroSD and also Tinker Questions Firmware	6	2410	December 11, 2014
Dropping the connection to spark cloud Troubleshooting	94	13404	February 21, 2016

Two Cores, One SD

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