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usb to CFC chip

Dear group

I am making a 300kBps data logger. DS89C420 and standard 50pins 1 to 8GB CF Card. All in a cell phone size epoxy tag. Instead of having the Dallas controller to do the data protocol out of the tag I'm thinking of having an USB chip do do the work. I need a chip (chip set) which connects to the CFC 50 pins in one end and an USB 4 pin port at the other ending up with a similar devise as those simpel flash card readers you can buy everywhere. Does this exists and how small could I expect to have it on my circuit board?

Kind regards Niels U. Kristiansen Aarhus University

Reply to
Niels U. Kristiansen
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Un bel giorno Niels U. Kristiansen digitò:

SMSC

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makes several of these interface chips, but I don't know how their chips are easy to find/buy.

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asd
Reply to
dalai lamah

There are single chip USB to IDE converter in QFP 128. You can fit all the logics inside the CF socket. But if you are using USB (2 to 3 MB/s, there is no point in using CF (over 10MB/s).

Reply to
linnix

While others have answered your question about such chips, I think the biggest problem you face is that your DS89C420 must implement an at least partial USB stack in order to talk to the chip you are looking for. This is by far WAY more complex than having your chip interface the CF directly and undoubtly will put much more load on it again compared to interfacing it directly. Interfacing a CF card on the hardware layer is pretty straight foreward and provided you have a reasonable datarate can be done with bitbangin on some gpio pins. Apart from this you would have to implement some sort of filesystem in both scenarios anyways. Now, if you want to simplify the interface or take of load from the DS89C420 why not use an aditional uC directly interfacing the CF card also handling the filesystem and define a simple (i.e. serial) protocol between the DS89C420 and said uC?

Just my 2¢ of course

Markus

Reply to
Markus Zingg

I don't think that's what he's trying to do. It sounded like he wanted to use the DS89C420 to log data into the CF, and a USBCF chip to get the data back out when he plugs it into a PC. Problem is finding the chip, multiplexing, and making sure you create a file system the chip is willing to read.

Reply to
cs_posting

Thanks. I misread it too. The ideal way is to use a USB capable Lexar CF. Unfortunately, they never publish the wirings and no other manufacturers follow this special feature.

Reply to
linnix

Correct, thank you. Looks like there are many of those devices on the market:

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Even though DS89C420 is a very strong controller and especially fit for my application it is in a way old fassion. 5V only as one example and my USB idea might end here.

Niels

Reply to
Niels U. Kristiansen

At the risk of once again misunderstanding you, the CF's can operate on 5V and 3.3V and I asume that the datalogger (hence the DS89C420 ) will be idle / powered down if you use the USB chip. So IMHO you only have to make sure the DS89C420 is isolated from the CF pins at the point in time the USB chip is active - no?

Markus

Reply to
Markus Zingg

This is all correct. And DS89C420 should not care much about 3.3V traffic if it is in idle or power down mode. Perhaps I will only have to isolate the power pins.

Niels

Reply to
Niels U. Kristiansen

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