Table 219. Smbus Timeout Specifications; Figure 285. Timeout Intervals For T Low:sext , T Low:mext - STMicroelectronics STM32WLEx Reference Manual

RM0461
Timeouts
This peripheral embeds hardware timers in order to be compliant with the three timeouts
defined in SMBus specification.
Symbol
t
TIMEOUT
t
LOW:SEXT
t
LOW:MEXT
1. t
LOW:SEXT
from the initial START to the STOP. It is possible that, another slave device or the master also extends the
clock causing the combined clock low extend time to be greater than t
measured with the slave device as the sole target of a full-speed master.
2. t
LOW:MEXT
message as defined from START-to-ACK, ACK-to-ACK, or ACK-to-STOP. It is possible that a slave device
or another master also extends the clock causing the combined clock low time to be greater than t
on a given byte. Therefore, this parameter is measured with a full speed slave device as the sole target of
the master.
SMBCLK
SMBDAT

Table 219. SMBus timeout specifications

Detect clock low timeout
(1)
Cumulative clock low extend time (slave device)
(2)
Cumulative clock low extend time (master device)
is the cumulative time a given slave device is allowed to extend the clock cycles in one message
is the cumulative time a master device is allowed to extend its clock cycles within each byte of a
Figure 285. Timeout intervals for t
Start
t
LOW:MEXT
Inter-integrated circuit (I2C) interface
Parameter
LOW:SEXT
t
LOW:SEXT
Clk
Ack
t
LOW:MEXT
RM0461 Rev 5
Limits
Min Max
25 35
- 25
- 10
. Therefore, this parameter is
LOW:SEXT
, t .
LOW:MEXT
Stop
Clk
Ack
t
LOW:MEXT
Unit
ms
LOW:MEXT
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