Texas Instruments VCA8613EVM User Manual page 11

To change between modes:
1) Select the mode of operation and set the switches accordingly.
2) Press S2 (reset) to change the mode of operation.
Note:
When in PC-Control mode, it is not necessary to press S2 to change the
modes selected on the PC. The microcontroller is programmed to accept the
changes automatically when the software is used to control the VCA8613.
The third mode of operation is accessed by setting the mode of operation to
PC-Control mode, disconnecting the jumpers on JP3, and connecting external
chip select, data in, clock, and data out to connectors J5, J6, J7, and J8, re-
spectively. This allows for direct control of the VCA8613 with an external con-
trol source such as a digital word generator. Resistor pads (R6 to R9) are pro-
vided onboard for termination of the externally provided signals, if needed. The
value of 50Ω can be adjusted to any value that is required by the drive circuitry
of the external signals.
CW modes are documented in Table 2.
Table 2. CW Modes Explained
Channel In
CW Mode 1
CW Mode 2
CW Mode 3
Output channel is listed as CW0 through CW9, or Overflow. Overflow effective-
ly disables the CW output from that channel.
5.1 PC-Control Mode
When the S1 switches are set to PC-Control mode, the VCA8613 is controlled
by the software running on a PC. At this point, the serial cable included with
the VCA8613EVM must be connected to the PC serial port. The program then
sets the proper baud rate for communication with the VCA8613EVM.
Ch1 Ch2 Ch3
CW 0 CW 1 CW 2
CW 8 CW 9 Overflow
Overflow Overflow CW 0
Modes of Operation
Ch4 Ch5 Ch6 Ch7
CW 3 CW 4 CW 5 CW 6 CW 7
Overflow CW 8 CW 4 CW 5 CW 1
Overflow CW 1 CW 4 CW 4 CW 9
VCA8613EVM
Ch8
5