REV. 0

AD1953

–26–

Table VIII. Parameter RAM Read/Write Format (Single Address)

Byte 0

Byte 1

Byte 2

Byte 3

Byte 4

00000, R/Wb, Adr[9:8]

Adr[7:0]

00, Param[21:16]

Param[15:8]

Param[7:0]

ADR

Byte 5 Byte 8

Byte 6 Byte 9

Byte 7 Byte 10

ADR + 1 ADR + 2

Table IX. Parameter RAM Block Read/Write Format (Burst Mode)

Byte 0

Byte 1

Byte 2

Byte 3

Byte 4

00000, R/Wb, Adr[9:8]

Adr[7:0]

00, Param[21:16]

Param[15:8]

Param[7:0]

Table X. Program RAM Read/Write Format (Single Address)

Byte 0

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

00000, R/Wb, Adr[9:8] Adr[7:0]

00000, Prog[34:32]

Prog[31:24]

Prog[23:16]

Prog[15:8]

Prog[7:0]

Table XI. Program RAM Block Read/Write Format (Burst Mode)

Byte 0

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

00000, R/Wb, Adr[9:8]Adr[7:0] 00000, Prog[34:32] Prog[31:24] Prog[23:16] Prog[15:8] Prog[7:0]

ADR

Byte 7

Byte 12

Byte 8

Byte 13

Byte 9

Byte 14

Byte 10 Byte 15

Byte 11 Byte 16

ADR + 1 ADR + 2

Table XII. SPI Control Register 1 Write Format

Byte 0

Byte 1

Byte 2

Byte 3

00000, R/Wb, Adr[9:8]

Adr[7:0]

00, Bit[13:8]

Bit[7:0]

Table XIII. SPI Control Register 1 Read Format

Byte 0

Byte 1

Byte 2

00000, R/Wb, Adr[9:8]

Adr[7:0]

000000, Bit[1:0]

Table XIV. SPI Control Register 2 Write Format

Byte 0

Byte 1

Byte 2

Byte 3

00000, R/Wb, Adr[9:8]

Adr[7:0]

000000, Bit[9:8]

Bit[7:0]

Table XV. SPI Volume Register Write Format

Byte 0

Byte 1

Byte 2

Byte 3

Byte 4

000000, Adr[9:8]

Adr[7:0]

00, Volume[21:16]

Volume[15:8]

Volume[7:0]

SPI READ/WRITE DATA FORMATS

The read/write formats of the SPI port are designed to be byte-

oriented. This allows for easy programming of common

microcontroller chips to fit into a byte-oriented format; 0s are

appended to the data fields to extend the data-word to the next

multiple of eight bits. For example, 22-bit words written to the

SPI parameter RAM are appended with two leading zeros to

reach 24 bits (three bytes), and 35-bit words written to the

program RAM are appended with five zeros to reach 40 bits

(five bytes). These zero-extended data fields are appended to

a 2-byte field consisting of a read/write bit and a 10-bit address.

The SPI port knows how many data bytes to expect based on

the address that is received in the first two bytes.

The total number of bytes for a single-location SPI write command

can vary from four bytes (for a control register write), to seven

bytes (for a program RAM write). Block writes may be used to

fill contiguous locations in program RAM or parameter RAM.