ST7LIT10BF1 STMicroelectronics, ST7LIT10BF1 Datasheet - Page 90

• Manufacturer Part Number: ST7LIT10BF1
• Description: 8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, DATA EEPROM, ADC, 5 TIMERS, SPI
• Manufacturer: STMicroelectronics

Specifications of ST7LIT10BF1

• Up To 4 Kbytes Single Voltage Extended Flash (xflash) Program Memory With Read-out Protection, In-circuit Programming And In-application Programming (icp And Iap). 10k Write/erase Cycles Guaranteed, Data Retention: 20 years at 55˚C.
• 128 Bytes Data Eeprom With Read-out Protection. 300k Write/erase Cycles Guaranteed, Data Retention: 20 years at 55˚C.
• Clock Sources: Internal 1% RC oscillator (on ST7FLITE15B and ST7FLITE19B), crystal/ceramic resonator or external clock
• Five Power Saving Modes: Halt, Active-Halt, Auto Wake-up from Halt, Wait and Slow

ST7LITE1xB
SERIAL PERIPHERAL INTERFACE (cont’d)
11.4.5 Error Flags
11.4.5.1 Master Mode Fault (MODF)
Master mode fault occurs when the master de-
vice’s SS pin is pulled low.
When a Master mode fault occurs:
Clearing the MODF bit is done through a software
sequence:
1. A read access to the SPICSR register while the
2. A write to the SPICR register.
Notes: To avoid any conflicts in an application
with multiple slaves, the SS pin must be pulled
high during the MODF bit clearing sequence. The
SPE and MSTR bits may be restored to their orig-
inal state during or after 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 multimaster configuration the device can be in
slave mode with the MODF bit set.
The MODF bit indicates that there might have
been a multimaster conflict and allows software to
handle this using an interrupt routine and either
perform a reset or return to an application default
state.
Figure 58. Clearing the WCOL Bit (Write Collision Flag) Software Sequence
90/159
1
1st Step
2nd Step
– The MODF bit is set and an SPI interrupt re-
– The SPE bit is reset. This blocks all output
– The MSTR bit is reset, thus forcing the device
quest is generated if the SPIE bit is set.
from the device and disables the SPI periph-
eral.
into slave mode.
MODF bit is set.
Clearing sequence after SPIF = 1 (end of a data byte transfer)
Clearing sequence before SPIF = 1 (during a data byte transfer)
1st Step
2nd Step
Read SPICSR
Read SPIDR
RESULT
SPIF = 0
WCOL = 0
Read SPICSR
Read SPIDR
RESULT
WCOL = 0
11.4.5.2 Overrun Condition (OVR)
An overrun condition occurs when the master de-
vice has sent a data byte and the slave device has
not cleared the SPIF bit issued from the previously
transmitted byte.
When an Overrun occurs:
– The OVR bit is set and an interrupt request is
In this case, the receiver buffer contains the byte
sent after the SPIF bit was last cleared. A read to
the SPIDR register returns this byte. All other
bytes are lost.
The OVR bit is cleared by reading the SPICSR
register.
11.4.5.3 Write Collision Error (WCOL)
A write collision occurs when the software tries to
write to the SPIDR register while a data transfer is
taking place with an external device. When this
happens, the transfer continues uninterrupted and
the software write will be unsuccessful.
Write collisions can occur both in master and slave
mode. See also
agement.
Note: A "read collision" will never occur since the
received data byte is placed in a buffer in which
access is always synchronous with the CPU oper-
ation.
The WCOL bit in the SPICSR register is set if a
write collision occurs.
No SPI interrupt is generated when the WCOL bit
is set (the WCOL bit is a status flag only).
Clearing the WCOL bit is done through a software
sequence (see
generated if the SPIE bit is set.
Note: Writing to the SPIDR register in-
stead of reading it does not reset the
WCOL bit.
Figure
Section 0.1.3.2 Slave Select Man-
6).