TV Converter Box User Manual

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USB-MODEVM Protocol

If the command is sent with no problem, the returning byte [0] is the same as the sent one logically ORed

with 0x20 - in the preceding first example, the returning packet is:

[0] 0x31

[1] 0xA0

[2] 0x02

[3] 0x05

[4] 0xAA

[5] 0x55

If for some reason the interface fails (for example, the I

C device does not acknowledge), it comes back

as:

[0] 0x51 --> interface | INTF_ERROR

[1] 0xA0

[2] 0x02

[3] 0x05

[4] 0xAA

[5] 0x55

If the request is malformed, that is, the interface byte (byte [0]) takes on a value which is not as preciously

described, the return packet is:

[0] 0x93 --> the user sent 0x13, which is not valid, so 0x93 returned

[1] 0xA0

[2] 0x02

[3] 0x05

[4] 0xAA

[5] 0x55

The preceding examples used writes. Reading is similar:

Read two bytes from device starting at register 5 of an I

C device with address A0:

[0] 0x01

[1] 0xA0

[2] 0x02

[3] 0x05

The return packet is:

[0] 0x21

[1] 0xA0

[2] 0x02

[3] 0x05

[4] 0xAA

[5] 0x55

assuming that the preceding values starting at Register 5 were actually written to the device.

SLAU286 – June 2009 USB-MODEVM Protocol 47

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