Signal Descriptions
Counter Clock
Board label:
CNT_CLK
Grid location:
B3
Description:
This is the 1.25 MHz clock signal for the 7-bit Counter Output described next.
Counter Output Bits
Board label:
CNT_OUT_0: CNT_OUT_6
Grid location:
A3, B3
Description:
These are the 7-bits of the binary counter. The LSB is CNT_OUT_0. It runs at 625 KHz, which is half of the
counter input clock.
The Counter Output Bits and the Counter Clock signals are on eight adjacent sets of header pins for easy connection to a
digital probe.
Crosstalk
Board label:
XTALK1, XTALK2
Grid location:
D8
Description:
These two signals have signi
fi
cant crosstalk between them. Use them to show MagniVu.
DAC Input, Parallel
Board label:
DAC_IN0, DAC_IN1, DAC_IN2, DAC_IN3, DAC_IN4, DAC_IN5, DAC_IN6, DAC_IN7
Grid location:
H3, H4
Description:
These signals are the input to the DAC. These are also the 8-bit parallel output signals of the port expander
in the middle of the mixed signal chain. The sine wave data from the SPI bus is converted to 8 parallel bits to drive the
DAC. DAC_IN0 is the LSB. (See Figure 1.)
See the SPI Bus description for packet details.
8
Tektronix MDO Demo 1 Board Instruction Manual