Microchip Technology ADM00732, Руководство пользователя

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HV7358DB1 GUI Operation
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2020 Microchip Technology Inc. DS50002951A-page 31
The “TXRW Low Time” is the programmable time allowed for the SPI or I
2
C bus to
complete all required read/write commands after the pulse is completed. It is actually
part of the LD time calculated above. It can be calculated using
Equation 3-5 .
EQUATION 3-5:
Choose the required “TXRW Low Time” and use Equation 3-5 to determine the “TXRW
Low Time Cycles”. Enter the “Line Duration Cycles” in the box and enter the “TXRW
Low Time Cycles” in the box, as shown in
Figure 3-10 .
FIGURE 3-10: “Line Duration” and “TXRW Low Time”.
3.4.7 Waveform Definition
The “Waveform Definition” box is shown in Figure 3-11 .
The HV7358 can store four different waveforms in the beamformer. They are
numbered: Waveform 0 through Waveform 3.
TGP:
Stands for Time Global Positive.
TGN:
Stands for Time Global Negative. These
signals are disabled in the GUI. They could be used to set the delay time on a per TX
x
basis.
TGW:
Sets the maximum TX Global Pulse Width (P
W
). It does this by setting the
number of F
C
time periods that the pulse remains high. The actual TGW is a 9-bit binary
word. The GUI accepts a number between 0 and 511 and makes the conversion. TGW
can be calculated from the following equation:
EQUATION 3-6:
P
W
is the default maximum pulse width for any of the TX pulses, either positive or negative.
RPC:
Sets the number of pulses in the waveform before returning to GND. If RPC = 1,
a single positive pulse will be defined. If RPC = 2, one positive and one negative pulse
will be done. RPC = 3 will be a positive, a negative and another positive pulse, etc.
The beamformer can hold up to four different waveforms. The parameters defined in
this box are “global”. A global waveform is the same for each TX(0) through TX(15), but
they can be different for each Waveform 0 through 3.
FIGURE 3-11: “Waveform Definition” Box.
Knowing the maximum pulse width, calculate TGW. Enter into the TGW box for each
waveform. Enter into the RPC box for each waveform. See
Figure 3-11 .
TXRW Cycles = (TXRW Low Time) x F
TCK
TGW P
W
x F
TCK