HV7358 datasheet(24/50 Pages) MICROCHIP

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HV7358

DS20005918A-page 24

 2018 Microchip Technology Inc.

4.4.1

BROADCASTING vs. DAISY-CHAIN

MODE

The fast programming interface can also operate in two

modes: Broadcasting mode or Daisy-Chain mode. The

pin, SPIB, selects the operating mode. When the SPIB

pin is high, the SPI interface operates in Broadcasting

mode. When SPIB = 0, it operates in Daisy-Chain

mode. Alternatively, the operating mode can be

selected via the SPIBC bit in the I2C register, to control

the SPI mode, if the override bit, SPISEL = 1.

In Daisy-Chain mode, the LVDS output SDO is the Shift

put, which is either the 12-bit Delay register DLY[11:0]

or 26-bit DLY[11:0], TLP[6:0] and TLN[6:0], depending

on the SDLY selection. Data is clocked out of the Trans-

mit Pattern Shift register onto SDO on the rising edge

of the CKOP.

In Broadcasting mode (pin SPIB = 1), the LVDS

outputs, CSOP/CSON and SDOP/SDON, are matched

in delay with the CKOP/CLON in timing, as shown in

Figure 4-16.

The Broadcasting mode should be used when all

devices need to be programmed with the same data. In

the medical ultrasound application, all the transmit

channels have the same transmit patterns. In that

scenario, the Broadcasting mode should be used to

reduce the programming time. The Daisy-Chain mode

should be used when the programming data is different

across devices. In most medical ultrasound applica-

tions, the transmit delay is different from channel to

channel. In that scenario, the Daisy-Chain mode

should be used when programming the channel delay

counters.

Note that the programming clocks, CLKP/N, are only

used for programming the transmit patterns and the

channel delay counters. The CLKP/N do not need to be

active all the time and they can be turned off after SPI

writing.

FIGURE 4-2:

Connection Circuit Block Diagram of Fast SPI Interface.

HV7358

LVDS

SDI

TXRW

Shift Reg.

SPIB

CLK

SDO

CSO

TXRW

CLK

SDI

FPGA

SDO

HV7358

SPIB

SDI

TXRW

Shift Reg.

SPIB

CLK

SDO

CSO

LVDS

SDI

TXRW

Shift Reg.

SPIB

CLK

SDO

CSO

CKO

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