Texas Instruments TLV320AIC3107EVM-K quick start Appendix G USB-MODEVM Protocol

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Appendix G USB-MODEVM Protocol

G.1 USB-MODEVM Protocol

The USB-MODEVM is defined to be a Vendor-Specific class, and is identified on the PC system as an NI-VISA device. Because the TAS1020 has several routines in its ROM which are designed for use with HID-class devices, HID-like structures are used, even though the USB-MODEVM is not an HID-class device. Data is passed from the PC to the TAS1020 using the control endpoint.

Data is sent in an HIDSETREPORT (see Table G-1):

Table G-1. USB Control Endpoint

HIDSETREPORT Request

Part	Value	Description
bmRequestType	0x21	00100001
bRequest	0x09	SET_REPORT
wValue	0x00	don't care
wIndex	0x03	HID interface is index 3
wLength	calculated by host
Data		Data packet as described below

The data packet consists of the following bytes, shown in Table G-2:

Table G-2. Data Packet Configuration

Byte Number	Type	Description
0	Interface	Specifies serial interface and operation. The two values are logically ORed.
		Operation:
		READ	0x00
		WRITE	0x10
		Interface:
		GPIO	0x08
		SPI_16	0x04
		I2C_FAST	0x02
		I2C_STD	0x01
		SPI_8	0x00
1	I2C Slave Address	Slave address of I2C device or MSB of 16-bit reg addr for SPI
2	Length	Length of data to write/read (number of bytes)
3	Register address	Address of register for I2C or 8-bit SPI; LSB of 16-bit address for SPI
4..64	Data	Up to 60 data bytes could be written at a time. EP0 maximum length is 64. The return
		packet is limited to 42 bytes, so advise only sending 32 bytes at any one time.

Example usage:

Write two bytes (AA, 55) to device starting at register 5 of an I2C device with address A0:

[0]0x11

[1]0xA0

[2]0x02

[3]0x05

[4]0xAA

[5]0x55

46 USB-MODEVM Protocol SLAU261–November 2008

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