Re: em28xx: msi Digivox ATSC board id [0db0:8810]

[Antti Palosaari <crope@iki.fi>]

On 12/12/2012 11:34 PM, Frank Schäfer wrote:
> Am 12.12.2012 22:25, schrieb Frank Schäfer:
>
> ...
>> Am 11.12.2012 21:59, schrieb Antti Palosaari:
>>> See current af9015 driver as example how driver makes decision which
>>> variant of NEC is used. You will need something similar. Read all 4
>>> NEC bytes from the hardware and then use driver to make decision which
>>> variant it is.
>> Yes, checking for inverted address and key code bytes would be a
>> possibility...
>
> The problem here is of course, that we have to configure the device first.
> So we need to know the protocol variant before getting any bytes from
> the device...

No, you now don't see the point correctly. If you read 4 byte "full NEC" 
code from the hardware, you will not need to know which variant it is 
for configure hardware. 4 byte, full NEC, presents all the variants.

Think it like NEC code is always 4 byte long as lower layer. All NEC 
remotes sends 4 byte codes regardless which variant. In receiver side, 
after decoding there is also 4 byte always. Variants are done very upper 
layer after decoding.

Let me take some existing examples:
------------------
rc-trekstor.c:	{ 0x0084, KEY_0 },
This is actually 1 byte NEC, which is device id == 0.
4 byte real code is: 00 ff 84 7b
------------------
rc-terratec-slim-2.c:	{ 0x800d, KEY_0 },
This is normal, traditional, oldest, most common, 2 byte NEC.
4 byte real code is: 80 7f 0d f2
------------------
rc-terratec-slim.c:	{ 0x02bd09, KEY_0 },
Extended NEC, quite common, 3 byte NEC.
4 byte real code is: 02 bd 09 f6
------------------
rc-tivo.c:	{ 0xa10c8c03, KEY_NUMERIC_0 },
"full" NEC, 4 byte NEC.
Not very common, but coming slowly more popular.
4 byte real code is: a1 0c 8c 03


As you can see all NEC variants could be presented as 4 byte NEC. Even 
the "one byte NEC", which comes in that case (rc-trekstor.c) "00 ff 84 
7b" as 4 byte real notation.


regards
Antti

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