HP E1340A, User Manual

Page: 243 / 295

Setting the Output
Function and
Loading RAM
The output function is set by selecting the DAC source, selecting a
waveform from the waveform EPROM, and then loading the waveform into
RAM.
The function is a one byte parameter. The value of the byte is the sum of
the bits set (bit weights). For example, to set a sine wave as the output
function and to load it into RAM 0, the value of the byte would be 128
which sets the bit pattern:
1 0 0 0 0 0 0 0
To set a triangle wave as the output function and load it into RAM 1, the
value of the byte would be 133, which sets the bit pattern:
1 0 0 0 0 1 0 1
Downloading an
Arbitrary Waveform
The DAC source when downloading an arbitrary waveform into RAM is the
Input Data Register (base + 0C
16
). Arbitrary waveforms are loaded into
RAM in the same manner as standard waveforms from the waveform
EPROM. For example, to download an arbitrary waveform into RAM 0, the
value of the "function" byte would be 0 which sets the bit pattern:
0 0 0 0 0 0 0 0
Arbitrary waveforms must have exactly 4096 points. Undefined points
appear at the output as random values. The “ Example Programs” section
demonstrates how to download and output arbitrary waveforms.
Download Mode
Bit 6 of the "setting the function and loading RAM" byte (Table C-2) is
used to control whether or not arbitrary waveform data appears at the output
as the data is loaded into RAM from the Input Data Register. Setting bit 6 to
"1" sets the output to 0V as the waveform is downloaded into RAM. When
bit 6 is set to "0", the output tracks the Input Data Register as the data is
loaded into RAM.
Multiple Waveforms in
a Single Output
Sequence
The AFG’s output signal can consist of up to four waveform segments
(RAM 0 through RAM 3). Each RAM is loaded from the waveform
EPROM, from the Input Data Register, or from both. An example of this
feature is located in the “Example Programs” section.
Appendix C HP E1340A Register-Based Programming 243