Us Old Farts
Nigel Goodwin said:
So perhaps you would care to inform us of your 'simple' way of accessing a USB memory card, with a zero-processor solution, and only a couple of standard TTL or CMOS chips?.
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I guess I'm not quite convinced that the SD card is a "USB device". It is certainly used in a lot of devices that use the USB interface to transfer the data but, the card itself is not capable of plugging directly into a USB port.
No, I'm not a young fart...I'm as old or older than yourself. My first real hobby effort that dealt seriously with memory was a digital oscilloscope and it only used about 7 or 8 discrete chips (8-bit sweep and vertical resolution with a blistering fast National Semiconductor A/D converter...rated for a conversion speed of 10 k samples/s but, I was pushing to its limits at about 35). Fun little project and it worked like a champ (in a lab environment of course since it needed external clocking from a pulse generator and such).
But, I do realize that there is a "problem" with the SD card right off the bat. There's just not enough contacts to be able to address it directly much less transfer data to/from it as well. That's why I posted my question here. Thus far, I've gotten zero practical information about programming the SD card from this source (if you look back through the thread there is NO info about the technical aspects of this task beyond the general and persistant admonition that you need to use a processor). This doesn't seem to be the right forum to glean this sort of info.
I'll go one step further. I saw the Z-80 chip (many moons ago and now see the PIC) as a "solution" to a lot of the things I wanted to do and, as a piece of hardware, could see how the instruction set could be implemented and the support chips interfaced. But, there seemed to be a gap of "expertise". That of getting the instructions to the chip (Z-80 or PIC) to do the actual work.
I'm not really much of a programmer and don't have a strong interest in it so, I'm always looking for "simplified instructions" but, while it seems like there should be some ABC approach to getting instructions to a device, in a practical sense, there doesn't really seem to be. It's sort of like a florist who enjoys flower arranging being made to learn about the properties of cow dung so as to make the flowers to be arranged.
When I look through the post (even for the PIC stuff) I find a lot of high-level throry being tossed around. I have to wonder just how many projects are actually being built and how many are just mental exercises. I certainly have nothing against mental exercises and by far the majority of the ideas I have will never see the heat of a soldering iron.
I've done a little BASIC programming but, always had the same ultimate problem as I have with my computer today (and, which I believe a lot of other hobbiests also see as a problem). As long as you're dealing with text and numbers and graphics, on the computer, you're pretty well supported. If you are using a device that someone else has determined you need (digital camera, printer, MP3 player, mic and headphone, etc.), you are still pretty well supported. If you want the computer to do anything else, you're pretty much in a wasteland. My "green house" post yielded a lot of good ideas but, virtually no practical solutions. That is, no fleshed-out, specific monitor or control devices that could be used.
Something I'd like to find (and, I'll bet a lot of other people could use, too) is a tutorial that does not assume either programming or hardware expertise but, concentrates on the procedural process of sending simple instructions from the human mind to a PIC (or other processor). That's the gap in my mind. I know what I want to do and I know what I want the hardware to do but, not sure how to get the twain to meet (to wax a bit poetic).
Now! All that should get me a pretty good ration of something, eh?