L9965P-FN datasheet(64/104 Pages) STMICROELECTRONICS

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3.14

Serial peripheral interface (SPI)

The IC integrates a Serial Peripheral Interface (SPI) to communicate with host controller.

Internal pullup resistors address open failures on SDI, NCS and SCLK pins.

Table 40. SPI quick look

Parameter

Description

Protocol

Out-of-frame

Single frame length

24-bit

Frame protection

5-bit CRC with poly = x^5+x^2+1 (0x25) and seed = 0b11111 (0x1F)

Max frequency

2 MHz

CPOL

CPHA

The protocol implements a Global Status Word (GSW) providing info on NVM status and FAULTN signal.

The frame format is shown in the Table 41.

Table 41. SPI frame format

Bit

9 8 7 6 5 4 3 2 1 0

MOSI

R/W

ADDRESS

DATA WRITE

CRC

MISO

SPI ERR

ADDRESS FEEDBACK

GSW

DATA READ

CRC

MOSI frame:

•

[23] bit: R/W flag selects if the current operation is a read (0) or write (1) operation

•

[22-17] bit field: SPI register address

•

[16-15] bit field: reserved, fixed to 00

•

[14-5] bit field: data write

•

[4-0] bit field: CRC checksum generated by SPI controller

MISO frame:

•

[23] bit: SPI error flag: the previous frame has an error due to length (long or short), stuck, wrong CRC,

wrong command or wrong address

•

[22-17] bit field: SPI register address feedback. Last received valid frame address feedback

•

[16-15] bit field: global status word (GSW), provides information related to NVM status and IC high level

error (NVM_BUSY on bit 16, FAULTN_ECHO on bit 15)

•

[14-5] bit field: data read

•

[4-0] bit field: CRC checksum generated by SPI

The following errors can be detected and the correspondent error flag is set in SPI_STATUS register:

•

Frame with less than 24 bits. The SPI_FRAME_SHORT bit is set.

•

Frame with more than 24 bits. The SPI_FRAME_LONG bit is set.

•

Frame with a wrong CRC. The SPI_CRC_ERROR bit is set.

•

Frame with a wrong address. The SPI_ADDRESS_ERROR bit is set.

•

Frame with an error (OR of previous errors). The SPI_FRAME_ERROR bit is set.

L9965P

Functional description

DS14702 - Rev 4

page 64/104

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