Table 145. Smbus Timeout Specifications; Figure 278. Timeout Intervals For T - ST STM32F423 Reference Manual

RM0430
Timeouts
This peripheral embeds hardware timers in order to be compliant with the 3 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 will also extend
the clock causing the combined clock low extend time to be greater than t
parameter is 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 will also extend the clock causing the combined clock low time to be greater than
t
LOW:MEXT
target of the master.
Fast-mode Plus Inter-integrated circuit (FMPI2C) interface

Table 145. 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
on a given byte. Therefore, this parameter is measured with a full speed slave device as the sole

Figure 278. Timeout intervals for t

Parameter
LOW:SEXT
RM0430 Rev 8
Limits
Min Max
25 35
- 25
- 10
. Therefore, this
LOW:SEXT
, t .
LOW:MEXT
817/1324
Unit
ms
ms
ms
847