Datasheet DS28E18 (Maxim) - 24

link to page 24 DS28E18 1-Wire® to I2C/SPI Bridge with Command Sequencer Additionally, the subsequent sections will describe each device function command in detail. The device function commands are each 8-bit values and are shown in Table 1.
Table 1. Device Function Commands DEVICE COMMAND COMMAND CODE
Write Sequencer 11h Read Sequencer 22h Run Sequencer 33h Write Configuration 55h Read Configuration 6Ah Write GPIO Configuration 83h Read GPIO Configuration 7Ch Device Status 7Ah
Command Start (66h)
Command Start is used for device function commands. After the command start byte, the next byte transmitted is the length byte. This indicates the length of both the command (i.e., device function command) and parameters. The result of the command is provide in similar format. The command start structure does not require a strong pullup (SPU) until after the release byte. After the release byte, the command is started and a command dependent delay is put into effect with the SPU power being delivered to the 1-Wire bus. The command dependent delay and SPU power is needed to execute device function commands and sequencer commands when applicable.
Table 2. Command Start Description COMMAND START
Command Code 66h Length byte followed by command and parameters. The first byte after the length byte is the device Parameter Byte(s) function command. Process the command and parameters sequence. The command code is followed by a length byte followed by the device function command and parameters. Next, the master receives a two-byte inverted CRC-16 of the command start byte + length byte + command + parameters is sent. If the CRC-16 is correct, the master then sends the release byte (AAh). Usage Once the release byte is received, the command is started. At that time the master must provide strong pullup on the 1-Wire to power the device. The required delay is command dependent with a minimum delay of tOP. After the delay, the master reads a dummy byte for clocking purposes. After the dummy byte, the command result is read, length byte first, followed by a result byte, optional result data, and an inverted CRC-16. If the command is not supported, the response will have a length of 00h followed by the CRC-16 value of FFFFh. Command Restrictions None Verify Release byte is AAh. Device Operation Start command. Command Duration See tOP (command dependent). Result Command dependent followed by inverted CRC-16. 19-100832 www.maximintegrated.com Maxim Integrated | 24 Document Outline General Description Applications Benefits and Features Simplified Application Block Diagram Absolute Maximum Ratings Package Information 8 TDFN-EP Electrical Characteristics Electrical Characteristics (continued) Typical Operating Characteristics Pin Configuration DS28E18 Pin Description Functional Diagram Block Diagram Detailed Description 64-Bit ROM ID Power-Up ROM ID Serialization 1-Wire Bus System Hardware Configuration Transaction Sequence Initialization 1-Wire ROM Function Commands Search ROM [F0h] Read ROM [33h] Match ROM [55h] Skip ROM [CCh] Resume [A5h] Overdrive-Skip ROM [3Ch] Overdrive-Match ROM [69h] 1-Wire Signaling and Timing Read/Write Time Slots Master-to-Slave Slave-to-Master Improved Network Behavior Device Function Commands Command Start (66h) Write Sequencer Command (11h) Read Sequencer Command (22h) Run Sequencer Command (33h) Device Configuration and Status Commands Write Configuration Command (55h) Read Configuration Command (6Ah) Write GPIO Configuration (83h) Read GPIO Configuration (7Ch) Device Status Command (7Ah) Sequencer Commands I2C Sequencer Interface Commands I2C Start Command I2C Stop Command I2C Write Data Command I2C Read Data Command I2C Read Data with NACK End Command SPI Sequencer Commands SPI Write/Read Byte(s) Command SPI Write/Read Bit(s) Command SS_HIGH Command SS_LOW Command Sequencer Utility Commands GPIO_CTRL Write Command GPIO_CTRL Read Command GPIO_BUF Write Command GPIO_BUF Read Command Delay Command SENS_VDD On Command SENS_VDD Off Command I2C Overview I2C Definitions Bus Idle or Not Busy START Condition STOP Condition Repeated START Condition Data Valid SPI Overview SPI Timing SPI Timing Diagram Power-Up of GPIO/I2C Pins Timeout Typical Application Circuits DS28E18 Configured as an I2C Master Typical Application Circuits (continued) DS28E18 Configured as an SPI Master Ordering Information Revision History