CS5484 datasheet(27/67 Pages) CIRRUS

27 / 67 page

CS5484

DS981F3

6. HOST COMMANDS AND REGISTERS

6.1 Host Commands

The first byte sent to the CS5484 SDI/RX pin contains

the host command. Four types of host commands are

required to read and write registers and instruct the

calculation engine. The two most significant bits (MSBs)

of the host command defines the function to be

performed. The following table depicts the types of

commands.

Table 2. Command Format

6.1.1 Memory Access Commands

The CS5484 memory has 12-bit addresses and is

organized as P5 P4 P3 P2 P1 P0 A5 A4 A3 A2 A1 A0 in

64 pages of 64 addresses each. The higher 6 bits

specify the page number. The lower 6 bits specify the

address within the selected page.

6.1.1.1 Page Select

A page select command is designated by setting the two

MSBs of the command to binary ‘10’. The page select

command provides the CS5484 with the page number

of the register to access. Register read and write

commands access 1 of 64 registers within a specified

page. Subsequent register reads and writes can be

performed once the page has been selected.

Figure 18. Byte Sequence for Page Select

6.1.1.2 Register Read

A register read is designated by setting the two MSBs of

the command to binary ‘00’. The lower 6 bits of the

been received, the CS5484 will send 3 bytes of register

data onto the SDO/TX pin.

Figure 19. Byte Sequence for Register Read

6.1.1.3 Register Write

A register write command is designated by setting the

two MSBs of the command to binary ‘01’. The lower 6

bits of the register write command are the lower 6 bits of

the 12-bit register address. A register write command

must be followed by 3 bytes of data.

Figure 20. Byte Sequence for Register Write

6.1.2 Instructions

An instruction command is designated by setting the

two MSBs of the command to binary '11'. An Instruction

command will interrupt any process currently running

and initiate a new process in the CS5484.

Figure 21. Byte Sequence for Instructions

These new processes include calibration, power

control, and soft reset. The following table depicts the

types of instructions. These new processes include

calibration, power control, and soft reset. The following

table depicts the types of instructions. Note that when

the CS5484 is in continuous conversion mode, an

unexpected or invalid instruction command could cause

the device to stop continuous conversion and enter an

unexpected operation mode. The host processor should

keep monitoring the CS5484 operation status and react

accordingly.

Function

Binary Value

Note

Read

0 0 A5 A4 A3 A2 A1 A0

A[5:0] specifies the

Write

0 1 A5 A4 A3 A2 A1 A0

Page Select

1 0 P5 P4 P3 P2 P1 P0

P[5:0] specifies the

page.

Instruction

1 1 C5 C4 C3 C2 C1 C0

C[5:0] specifies the

instruction.

SDI/RX

Page Select Cmd.

SDO/TX

SDI/RX

DATA

Read Cmd.

SDI/RX

DATA

Write Cmd.

SDI/RX

Instruction

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