SCAS290 datasheet(50/53 Pages) TI

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Writing Scripts

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The first command, I, sets the interface to use for the commands to follow. This command must be

followed by one of the following parameters:

i2cstd

Standard mode I

2C bus

i2cfast

Fast mode I

2C bus

spi8

SPI bus with 8-bit register addressing

spi16

SPI bus with 16-bit register addressing

gpio

Use the USB-MODEVM GPIO capability

For example, if a fast mode I

2C bus is to be used, the script begins with:

I i2cfast

A double quoted string of characters following the b command can be added to provide information to the

user about each breakpoint. When the script is executed, the software's command handler halts as soon

as a breakpoint is detected and displays the string of characters within the double quotes.

The Wait for Flag command, f, reads a specified register and verifies if the bitmap provided with the

command matches the data being read. If the data does not match, the command handler retries for up to

200 times. This feature is useful when switching buffers in parts that support the adaptive filtering mode.

The command f syntax follows:

f [i2c address] [register] [D7][D6][D5][D4][D3][D2][D1][D0] where 'i2c address' and 'register'

are in hexadecimal format and 'D7' through 'D0' are in binary format with values of 0, 1 or X for

don't care.

Anything following a comment command # is ignored by the parser, provided that it is on the same line.

The delay command d allows the user to specify a time, in milliseconds, that the script pauses before

proceeding. The delay time is entered in decimal format.

A series of byte values follows either a read or write command. Each byte value is expressed in

hexadecimal, and each byte must be separated by a space. Commands are interpreted and sent to the

TAS1020B by the program using the protocol described in Section G.1.

The first byte following an r (read) or w (write) command is the I

2C slave address of the device (if I2C is

used) or the first data byte to write (if SPI is used—note that SPI interfaces are not standardized on

protocols, so the meaning of this byte varies with the device being addressed on the SPI bus). The

second byte is the starting register address that data will be written to (again, with I

2C; SPI varies—see

Section G.1 for additional information about what variations may be necessary for a particular SPI mode).

Following these two bytes are data, if writing; if reading, the third byte value is the number of bytes to

read, (expressed in hexadecimal).

For example, to write the values 0xAA 0x55 to an I

2C device with a slave address of 0x30, starting at a

#example script I i2cfast w 30 03 AA 55 r 30 03 02

This script begins with a comment, specifies that a fast I

2C bus will be used, then writes 0xAA 0x55 to the

2C slave device at address 0x30, writing the values into registers 0x03 and 0x04. The script then reads

back two bytes from the same device starting at register address 0x03. Note that the slave device value

does not change. It is unnecessary to set the R/W bit for I

2C devices in the script; the read or write

commands does that.

If extensive repeated write commands are sent and commenting is desired for a group of bytes, the >

command can be used to extend the bytes to other lines that follow. A usage example for the > command

follows:

#example script for '>' command I i2cfast # Write AA and BB to registers 3 and 4, respectively w

30 03 AA BB # Write CC, DD, EE and FF to registers 5, 6, 7 and 8, respectively > CC DD EE FF #

Place a commented breakpoint b "AA BB CC DD EE FF was written, starting at register 3" # Read

back all six registers, starting at register 3 r 30 03 06

The following example demonstrates usage of the Wait for Flag command, f:

#example script for 'wait for flag' command I i2cfast # Switch to Page 44 w 30 00 2C # Switch

buffers w 30 01 05 # Wait for bit D0 to clear. 'x' denotes a don't care. f 30 01 xxxxxxx0

USB-MODEVM Protocol

SLAU266A – October 2008 – Revised October 2012

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