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USB-MODEVM Protocol
Do the same with a fast mode I
2
C device:
[0]
0x12
[1]
0xA0
[2]
0x02
[3]
0x05
[4]
0xAA
[5]
0x55
Now with an SPI device which uses an 8-bit register address:
[0]
0x10
[1]
0xA0
[2]
0x02
[3]
0x05
[4]
0xAA
[5]
0x55
Now, do a 16-bit register address, as found on parts like the TSC2101. Assume the register address
(command word) is
0x10E0
:
[0]
0x14
[1]
0x10
→
Note:
the I
2
C address now serves as MSB of reg addr.
[2]
0x02
[3]
0xE0
[4]
0xAA
[5]
0x55
In each case, the TAS1020 returns, in an HID interrupt packet, the following:
[0]
interface byte | status
status:
REQ_ERROR 0x80
INTF_ERROR 0x40
REQ_DONE 0x20
[1]
for I
2
C interfaces, the I
2
C address as sent
for SPI interfaces, the read back data from SPI line for transmission of the corresponding byte
[2]
length as sent
[3]
for I
2
C interfaces, the reg address as sent
for SPI interfaces, the read back data from SPI line for transmission of the corresponding byte
[4..60]
echo of data packet sent
SLAU282 – April 2009
USB-MODEVM Protocol
29
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