L9963E datasheet(23/184 Pages) STMICROELECTRONICS

23 / 184 page

Figure 9. Isolated SPI interface

Table 16. Isolated SPI quick look

Parameter

Description

Protocol

Half-Duplex / Out of frame

Single Frame Length

40 bit

Addressable Devices

Frame protection

6 bit CRC

Max. Bit-rate

2.66 Mbps (high speed configuration)

333 kbps (low speed configuration, default)

Master/Slave configuration

L9963E Slave

The transmission line on the isolated SPI exploits a single twisted pair. Communication data is transmitted/

received over a pulse-shaped signal, in a half-duplex protocol.

Line bit-rate can be selected by programming the iso_freq_sel bit via SPI. A single bit is made of a pulse time

(TPULSE) followed by two pause slices (2TPULSE).:

•

TPULSE = 2TBIT_HIGH_LOW_FAST for the high speed configuration

•

TPULSE = 2TBIT_HIGH_LOW_SLOW for the low speed configuration

Once the operating frequency has been programmed and the ISOH port has been enabled/disabled, it is possible

to lock these settings by writing the Lock_isoh_isofreq bit to ‘1’, to avoid unwanted changes due to wrong MCU

write frame.

Lock_isoh_isofreq is added to the reg map into a separate register in respect to isotx_en_h and iso_freq_sel,

in order to avoid that a single frame can both unlock and write fields

Lock_isoh_isofreq bit (default 0) is reset every time the device goes to a low power mode. When

Lock_isoh_isofreq is set to ‘1’, isotx_en_h and iso_freq_sel bits are write protected

Architecture and MCU command’s time constraints are specified taking into account signal propagation delay over

the communication bus. Refer to Inter-frame delay for further details.

L9963E

Serial communication interface

DS13636 - Rev 12

page 23/184

L9963E Datasheet(PDF) 23 Page - STMicroelectronics