Mailing List Archive: MythTV: Users

Channel change misses 20% of the time, can I do USB to USB?

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openletter at yahoo

Jul 19, 2008, 6:40 AM

Post #1 of 6 (455 views)
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Channel change misses 20% of the time, can I do USB to USB?

I'm having problems with my updated hardware getting the channels changed correctly using my commandir. About 20% of the time the DirecTV HIRMD-E2 doesn't see one of the channel digits, so MythTV records one hour of channel 34 instead of 354, or channel 50 instead of 501, etc.

I set the delay time in the channel changing script to 1.2 seconds, but that doesn't seem to make any difference. The setup worked fine before I upgraded from an old Athlon XP (32 bit) to a new AMD 64 2.2 GHz, with totally fresh install of Ubuntu 8.04.

So I'm thinking I can solve the problem by by replacing the HIRMD-E2 with an H20-600 and using the USB port. But the problem is that I need to use my one serial port for the UPS as I have frequent power outage issues where I live (12 power outages last January).

Is there a way to use LIRC by just going USB to USB instead of USB to serial?

Or is there something else I can do to fix the channel change problem?

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jppoet at gmail

Jul 19, 2008, 8:19 AM

Post #2 of 6 (435 views)
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Re: Channel change misses 20% of the time, can I do USB to USB? [In reply to]

On Sat, Jul 19, 2008 at 7:40 AM, Paul <openletter[at]yahoo.com> wrote:
> I'm having problems with my updated hardware getting the channels changed correctly using my commandir. About 20% of the time the DirecTV HIRMD-E2 doesn't see one of the channel digits, so MythTV records one hour of channel 34 instead of 354, or channel 50 instead of 501, etc.
>
> I set the delay time in the channel changing script to 1.2 seconds, but that doesn't seem to make any difference. The setup worked fine before I upgraded from an old Athlon XP (32 bit) to a new AMD 64 2.2 GHz, with totally fresh install of Ubuntu 8.04.
>
> So I'm thinking I can solve the problem by by replacing the HIRMD-E2 with an H20-600 and using the USB port. But the problem is that I need to use my one serial port for the UPS as I have frequent power outage issues where I live (12 power outages last January).
>
> Is there a way to use LIRC by just going USB to USB instead of USB to serial?
>
> Or is there something else I can do to fix the channel change problem?

Yes.

I use a USB-to-Serial->Null Modem cable->Serial-to-USB cable to
connect my computer to my H20.

The H20 only understands a subset of the various USB/Serial adapters
out there. Mine uses the PL2303 chip.

I bought the USB/Serial adaptor at directron and the Null Modem cable
at monoprice.

Of course, you should read the wiki:
http://www.mythtv.org/wiki/index.php/Controlling_DirecTV_Set_Top_Box_%28STB%29_via_USB_or_Serial

John
--
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peter at vanderwal

Jul 23, 2008, 1:38 AM

Post #3 of 6 (373 views)
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Re: Channel change misses 20% of the time, can I do USB to USB? [In reply to]

> Is it possible to just run it through my parallel port? I'm not using
> that for anything, and it seems simpler.

It's possible, but not simple. Parallel and serial ports are very different.

You'd have to build and adapter and rewrite the software.

Basically you'd have to write a custom kernel serial driver for a couple
pins on the parallel port. Normal serial drivers just throw a whole byte
of data at the serial port and let the hardware take care of sending it
out one bit at a time. You'd have to write software that holds the bytes
of data, chops it up, and then sends it out a bit at a time (plus adding
start and stop bits) to one of the pins on the parallel port. At the same
time it would have to monitor another pin (continuously) and collect the
bits and put them back together into bytes.

I wrote similar code for this 25 years ago (different type of processor so
it won't work here), it was a pain and I didn't have to worry about making
it into a kernel driver or daemon that can run in the background.

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openletter at yahoo

Jul 23, 2008, 8:06 AM

Post #4 of 6 (379 views)
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Re: Channel change misses 20% of the time, can I do USB to USB? [In reply to]

John P Poet wrote:
> I use a USB-to-Serial->Null Modem
> cable->Serial-to-USB cable to
> connect my computer to my H20.
>
> The H20 only understands a subset of the various USB/Serial
> adapters
> out there. Mine uses the PL2303 chip.
>
> I bought the USB/Serial adaptor at directron and the Null
> Modem cable
> at monoprice.
>
> Of course, you should read the wiki:
> http://www.mythtv.org/wiki/index.php
/Controlling_DirecTV_Set_Top_Box_%28STB%29_via_USB_or_Serial
>
>
> John

This list rocks! Thanks, man.

There is a 'PTC Premium USB to Serial Converter for DB9 and DB25, Model:
USBA-S109' on Directron - is this the same you have? It doesn't say anything about the chip used.

Is it possible to just run it through my parallel port? I'm not using that for anything, and it seems simpler.

jppoet at gmail

Jul 23, 2008, 8:44 AM

Post #5 of 6 (374 views)
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Re: Channel change misses 20% of the time, can I do USB to USB? [In reply to]

On Wed, Jul 23, 2008 at 9:06 AM, Paul <openletter[at]yahoo.com> wrote:
> John P Poet wrote:
>> I use a USB-to-Serial->Null Modem
>> cable->Serial-to-USB cable to
>> connect my computer to my H20.
>>
>> The H20 only understands a subset of the various USB/Serial
>> adapters
>> out there. Mine uses the PL2303 chip.
>>
>> I bought the USB/Serial adaptor at directron and the Null
>> Modem cable
>> at monoprice.
>>
>> Of course, you should read the wiki:
>> http://www.mythtv.org/wiki/index.php
> /Controlling_DirecTV_Set_Top_Box_%28STB%29_via_USB_or_Serial
>>
>>
>> John
>
> This list rocks! Thanks, man.
>
> There is a 'PTC Premium USB to Serial Converter for DB9 and DB25,
> Model:
> USBA-S109' on Directron - is this the same you have? It doesn't say
> anything about the chip used.
>
> Is it possible to just run it through my parallel port? I'm not using that
> for anything, and it seems simpler.

You would be on your own trying to use your parallel port.

This is what I used:

http://www.directron.com/sbtusc1m.html
http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10212&cs_id=1021205&p_id=477&seq=1&format=2

John

PS. This list prefers text emails. You should turn off HTML in your
email client.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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openletter at yahoo

Jul 23, 2008, 9:22 AM

Post #6 of 6 (374 views)
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Re: Channel change misses 20% of the time, can I do USB to USB? [In reply to]

>You'd have to build and adapter and rewrite the software.

"Forget I asked."

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