ST72C334J2B6 STMicroelectronics, ST72C334J2B6 Datasheet - Page 79

• Manufacturer Part Number: ST72C334J2B6
• Description: 8-bit Microcontrollers - MCU Flash 8K SPI/SCI
• Manufacturer: STMicroelectronics

Specifications of ST72C334J2B6

• Product Category: 8-bit Microcontrollers - MCU
• Core: ST7
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 8 MHz
• Program Memory Size: 8 KB
• Data Ram Size: 384 B
• On-chip Adc: Yes
• Operating Supply Voltage: 3.2 V to 5.5 V
• Package / Case: SDIP-42
• Mounting Style: Through Hole
• A/d Bit Size: 8 bit
• A/d Channels Available: 8
• Data Rom Size: 256 B
• Interface Type: SCI, SPI
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 32
• Number Of Timers: 4 bit
• Program Memory Type: Flash
• Factory Pack Quantity: 13
• Supply Voltage - Max: 5 V
• Supply Voltage - Min: 3.2 V

SERIAL PERIPHERAL INTERFACE (Cont’d)
14.4.4.5 Master Mode Fault
Master mode fault occurs when the master device
has its SS pin pulled low, then the MODF bit is set.
Master mode fault affects the SPI peripheral in the
following ways:
Clearing the MODF bit is done through a software
sequence:
1. A read or write access to the SR register while
2. A write to the CR register.
Notes: To avoid any multiple slave conflicts in the
case of a system comprising several MCUs, the
SS pin must be pulled high during the clearing se-
quence of the MODF bit. The SPE and MSTR bits
– The MODF bit is set and an SPI interrupt is
– The SPE bit is reset. This blocks all output
– The MSTR bit is reset, thus forcing the device
generated if the SPIE bit is set.
from the device and disables the SPI periph-
eral.
into slave mode.
the MODF bit is set.
may be restored to their original state during or af-
ter this clearing sequence.
Hardware does not allow the user to set the SPE
and MSTR bits while the MODF bit is set except in
the MODF bit clearing sequence.
In a slave device the MODF bit can not be set, but
in a multi master configuration the device can be in
slave mode with this MODF bit set.
The MODF bit indicates that there might have
been a multi-master conflict for system control and
allows a proper exit from system operation to a re-
set or default system state using an interrupt rou-
tine.
14.4.4.6 Overrun Condition
An overrun condition occurs when the master de-
vice has sent several data bytes and the slave de-
vice has not cleared the SPIF bit issuing from the
previous data byte transmitted.
In this case, the receiver buffer contains the byte
sent after the SPIF bit was last cleared. A read to
the DR register returns this byte. All other bytes
are lost.
This condition is not detected by the SPI peripher-
al.
ST72334J/N, ST72314J/N, ST72124J
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