USB GPS ( demise of RS 232)

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Our supplier of GPS receivers has effectively cut off the supply (by hiking up the price 2x) of the RS232 receivers. They are offering the "same" unit but as USB for 1/3 the cost of the RS232.

As I only use the GPS for NMEA data stream, I am wondering what the most cost effective solution would be.

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Got some prices?
As reference, I'm buying venus chips from oz at AU$25 a piece in 1+ quantity... but they come down to $15.85 in 168+

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Quote:

As I only use the GPS for NMEA data stream, I am wondering what the most cost effective solution would be.

Your processor will need to present the module with USB host. Of all the AVRs the OTG mode on AT90USB647/1287 are the only ones that can do this. For others you'd need to add an external USB host chip like FTDI's Vincuulum (or whatever it's called).

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I am just doing a project for an existing product that required USB connection to a usb flash drive and used a VDRIVE2 module from fdti which communicates to my main board via rs232. Works very well

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Quote:

used a VDRIVE2

But that's not a generic host is it? I thought it was specifically for MSD? I think that under the hood it may be a Vincuulum but programmed specifically to act only as a host for MSD. What's needed here is a host that can support CDC-ACM

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I suspect the USB receiver internally still uses a serial connection. You could bypass the internal USB/Serial converter and tap directly into the serial signal there.

This requires opening and modifying the module, though.

Markus

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I think the real issue here is all of the GPS tracker designs out there. GPS will want to be a USB "slave" device. That means that it must be paired with either a USB master or a USB-OTG device. As a result, you no longer have a pair of relatively dumb async serial devices talking to each other. Now, the trackers need to behave like a master, and that raises the bar, substantially, You cannot simply drop in a FTDI FT232R and be happy as a clam.

'Tis a real disappointment.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net