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Guest Message by DevFuse

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Controlling H20 via serial or USB port?


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3 replies to this topic

#1 OFFLINE   kwoodrow

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Posted 12 January 2006 - 03:38 PM

I've heard that the H20 can be controlled through its USB port using a USB-to-serial converter. Is anyone tried it yet?

And does anyone know where I can find the RS232 control protocol for the H20 box?

Thanks!

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#2 OFFLINE   wmccain

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Posted 14 January 2006 - 05:32 AM

I've heard that the H20 can be controlled through its USB port using a USB-to-serial converter. Is anyone tried it yet?

And does anyone know where I can find the RS232 control protocol for the H20 box?

Thanks!


I've been wondering if this might be the case. If so, chances are reasonably good that it's the same 9600 bps "APG" protocol that has been "standard" on past DirecTV receivers (it was common across multiple brands: RCA, Sony, LG, etc.).

Can you say where you "heard" this?

One possible issue is the choice of USB-to-serial converter. There are basically two varieties on the market today, and they have different software drivers: Keyspan and "all others". The "all others" use the Prolific 2303 chipset.

William C. McCain
Palo Alto, California

#3 OFFLINE   kwoodrow

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Posted 17 January 2006 - 08:55 AM

I sent an email to D* customer service and received a reply the next day! The answer is YES, the H20 is serial controllable through its USB port. Acc'd to D*, the protocol for the D11 is essentially the same as the protocol for the H20. The HR20 protocol has not been released (nor has the box itself, for that matter).

- Ken

The protocol docs can be found online at sbcatest.com under Tech Updates (I can't post a link yet).

#4 OFFLINE   wmccain

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Posted 17 January 2006 - 02:35 PM

The protocol docs can be found online at sbcatest.com under Tech Updates.

Many thanks for getting this info. I followed your "link" and downloaded the protocol docs. This is the first time, to the best of my knowledge, that the serial interface protocol has been officially documented in documents available to the public (as opposed to OEM partners and other vendors). Previously, the serial interface protocol for DirecTV receivers was reverse engineered and posted on several "hobbyist" Web sites.

Some comments:

• The protocol is, in fact, the well-known "hex FA" protocol that has been used on all DirecTV receivers for many years. (The earliest version of this protocol is also known as the "MPG" protocol, where "MPG" refers to the original program guide. The current version of this protocol is known as the "APG" protocol, for "Advanced Program Guide".)

• The supported USB-to-serial adapters are, in fact, the ones with the Prolific 2303 chipset. This is essentially ALL currently-available USB-to-serial adapters EXCEPT the ones made by Keyspan. Which is "just-as-well" — the Prolific-based adapters can be found for as low as $14.95, whereas the Keyspan adapters sell for $39.95.

William C. McCain
Palo Alto, California




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