VNF9Q20F datasheet(30/109 Pages) STMICROELECTRONICS

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Data Consistency Check (Parity/CRC)

For some devices a Data Consistency Check is required. Therefore, either a parity-check or for very sensitive

systems a CRC may be implemented.

It is defined on 2 bits, in the SPI Mode register located in the ROM Part. A check is then applied on the incoming

frame (SDI) while a calculation elaborated on one/multiple bits is done and integrated on the outgoing frame

(SDO).

Table 30. SPI Data Consistency Check

Bit 1

Bit 0

Description

Not used

Parity used

CRC used

Invalid

In case either the Parity or the CRC check is implemented it is always located at the end of the communication.

The device is equipped with the parity control check.

4.4

Outputs control

Depending on the actual device mode, outputs can be controlled by the SPI register or the direct input DIx.

SPI register SOCR

In normal mode outputs can be turned ON/OFF, applying Bit[n] = 1/0 in the SOCR register.

[n]: is the related channel, n = 0 for the channel 0, and n = 3 for channel 3.

Procedure to turn-ON the outputs in PWM operations

The status of the output drivers is configured via the SPI output control register (SOCR), the direct input enable bit

“DIENCR” in the OUTCTRCR register, the PWM mode control register (PWMFCY) and the channel control

by the SOCR. The PWMFCY bit selects if the outputs operate in PWM mode. Please refer to the following table

for Output Control details in Normal Mode.

Table 31. Output control truth table

DIENCR (OUTCFGRx)

INx

SOCRx

DUTYCR

OUTPUTx

OFF

PWM

OFF

PWM

Note:

•

In normal mode, outputs can be driven by SPI commands or a combination of SPI commands and direct

inputs INx.

•

In fail-safe mode, the outputs are controlled by the direct inputs INx regardless of SPI commands. It is

possible to apply the PWM through the DIx inputs. The PWM unit is not active in fail-safe mode, it is still

possible to access the relevant registers and to configure them.

To turn on channels, information must enter into the following registers

•

Select the PWM frequency by using the two bits PWMFCYx

VNF9Q20F

SPI functional description

DS13909 - Rev 6

page 30/109

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