Datasheet

USB-MODEVM Protocol www.ti.com
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
2
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 previously
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
2
C device with address A0:
[0] 0x01
[1] 0xA0
[2] 0x02
[3] 0x05
28 USB-MODEVM Protocol SLAU285 – July 2009
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