Detailed description

SPV1020

12/19

Doc ID 17588 Rev 3

one command byte followed by data bytes whose direction depends on the type of

command. If the command byte requires data to be read from the register file, those data

are transmitted from the slave to the master through the MISO pin. Therefore the master

appends a number of NOPs (0x00) to the command so that the entire data can be

transmitted, see

Figure 4. The master must transmit a byte to receive a byte.

If the SS wire goes high before the completion of a command byte in the data frame, the

SPV1020 rejects that byte and the frame is closed. Then the next data frame is considered

as a new one, starting with a command byte.

Figure 4.

Frame structure: register read operation

The host can insert a short pause between each frame byte, or it can work in burst mode

(no pause between frame bytes).

Some data words can be longer than 8 bits, such as ADC results (10 bits). In such cases,

data is first extended to the nearest multiple of one byte (right justified). Then it is split into

bytes, e.g. the ADC result R is formatted as follows:

Table 7 shows a list of commands. Each command addresses a memory location of a

certain width and sets the direction of the related data.

Table 6.

Data format for words longer than 8 bits

Bit 7

MSB

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

LSB

Byte 1

0

000

00

R9

MSB

R8

Byte 2

R7

R6R5R4

R3R2

R1

R0

LSB