ST STM32F301 6 Series Reference Manual page 683

RM0366
appending a packet error code (PEC) at the end of each message transfer. The PEC is
calculated by using the C(x) = x
(including addresses and read/write bits).
The I2C peripheral embeds a hardware PEC calculator and allows a not acknowledge to be
sent automatically when the received byte does not match the hardware calculated PEC.
Timeouts
To comply with the SMBus timeout specifications, the I2C peripheral embeds hardware
timers.
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 target device or the controller also extends
the clock causing the combined clock low extend time to be greater than t
applies to a single target device connected to a full-target controller.
2. t
LOW:MEXT
a message as defined from START-to-ACK, ACK-to-ACK, or ACK-to-STOP. It is possible that a target
device or another controller also extends the clock, causing the combined clock low time to be greater than
t
LOW:MEXT
controller.
SMBCLK
SMBDAT
8
Table 91. SMBus timeout specifications
Detect clock low timeout
(1)
Cumulative clock low extend time (target device)
Cumulative clock low extend time (controller
(2)
device)
is the cumulative time a given target device is allowed to extend the clock cycles in one message
is the cumulative time a controller device is allowed to extend its clock cycles within each byte of
on a given byte. The value provided applies to a single target device connected to a full-target
Figure 269. Timeout intervals for t
Start
t
LOW:MEXT
Inter-integrated circuit interface (I2C)
2
+ x + x + 1 CRC-8 polynomial on all the message bytes
Parameter
LOW:SEXT
t
LOW:SEXT
Clk
Ack
t
LOW:MEXT
RM0366 Rev 5
Limits
Min Max
25 35
- 25
- 10
. The value provided
LOW:SEXT
, t
LOW:MEXT
Stop
Clk
Ack
t
LOW:MEXT
MS19866V1
Unit
ms
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