DS1722 Dallas, DS1722 Datasheet - Page 7

• Manufacturer Part Number: DS1722
• Description: Digital Thermometer with SPI/3-Wire Interface
• Manufacturer: Dallas

ADDRESS AND DATA BYTES
Address and data bytes are shifted MSB first into the serial data input (SDI) and out of the serial data
output (SDO). Any transfer requires the address of the byte to specify a write or a read, followed by one
or more bytes of data. Data is transferred out of the SDO for a read operation and into the SDI for a write
operation.
The address byte is always the first byte entered after CE is driven high. The most significant bit (A7) of
this byte determines if a read or write will take place. If A7 is "0", one or more read cycles will occur. If
A7 is "1", one or more write cycles will occur.
Data transfers can occur 1 byte at a time in multiple-byte burst mode. After CE is driven high an address
is written to the DS1722. After the address, one or more data bytes can be written or read. For a single-
byte transfer, 1 byte is read or written and then CE is driven low (see Figures 4 and 5). For a multiple-
byte transfer, however, multiple bytes can be read or written to the DS1722 after the address has been
written (see Figure 6). A single-byte burst read/write will sequentially point through the memory map
and will loop from 02h/82h to 00h/80h.
SPI SINGLE BYTE WRITE Figure 4
SPI SINGLE-BYTE READ Figure 5
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DS1722