C.2
GPIO Capability
C.3
Writing Scripts
www.ti.com
GPIO Capability
The return packet is:
[0]
0x21
[1]
0xA0
[2]
0x02
[3]
0x05
[4]
0xAA
[5]
0x55
assuming that the values written starting at Register 5 were actually written to the device.
The USB-MODEVM has seven GPIO lines. Access them by specifying the interface to be 0x08, and then
using the standard format for packets—but addresses are unnecessary. The GPIO lines are mapped into
one byte (see
):
Table C-3. GPIO Pin Assignments
Bit 7
6
5
4
3
2
1
0
x
P3.5
P3.4
P3.3
P1.3
P1.2
P1.1
P1.0
Example: write P3.5 to a 1, set all others to 0:
[0]
0x18
→
write, GPIO
[1]
0x00
→
this value is ignored
[2]
0x01
→
length - ALWAYS a 1
[3]
0x00
→
this value is ignored
[4]
0x40
→
01000000
The user can also read back from the GPIO to see the state of the pins. Assume the previous example
was just written to the port pins.
Example: read the GPIO
[0]
0x08
→
read, GPIO
[1]
0x00
→
this value is ignored
[2]
0x01
→
length - ALWAYS a 1
[3]
0x00
→
this value is ignored
The return packet is:
[0]
0x28
[1]
0x00
[2]
0x01
[3]
0x00
[4]
0x40
A script is simply a text file that contains data to send to the serial control buses.
Each line in a script file is one command. No provision is made for extending lines beyond one line, except
for the
>
command. A line is terminated by a carriage return.
The first character of a line is the command. Commands are:
i
Set interface bus to use
r
Read from the serial control bus
w
Write to the serial control bus
>
Extend repeated write commands to lines below a
w
#
Comment
b
Break
d
Delay
f
Wait for Flag
SLAU285 – July 2009
USB-MODEVM Protocol
29
