DocID025202 Rev 7
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RM0365
Inter-integrated circuit (I2C) interface
834
t
LOW:MEXT
for a master. As the standard specifies only a maximum, the user can choose
the same value for the both.
Then the timer is enabled by setting the TEXTEN bit in the I2C_TIMEOUTR register.
If the SMBus peripheral performs a cumulative SCL stretch for a time greater than
(T1) x 2048 x t
I2CCLK
, and in the timeout interval described in
section, the TIMEOUT flag is set in the I2C_ISR register.
Table 147: Examples of TIMEOUTB settings for various I2CCLK frequencies
Caution:
Changing the TIMEOUTB configuration is not allowed when the TEXTEN bit is set.
Bus Idle detection
In order to enable the t
IDLE
check, the 12-bit TIMEOUTA[11:0] field must be programmed
with the timer reload value in order to obtain the t
IDLE
parameter. The TIDLE bit must be
configured to ‘1 in order to detect both SCL and SDA high level timeout.
Then the timer is enabled by setting the TIMOUTEN bit in the I2C_TIMEOUTR register.
If both the SCL and SDA lines remain high for a time greater than (T1) x 4 x
t
I2CCLK
, the TIMEOUT flag is set in the I2C_ISR register.
Table 148: Examples of TIMEOUTA settings for various I2CCLK frequencies (max
Caution:
Changing the TIMEOUTA and TIDLE configuration is not allowed when the TIMEOUTEN is
set.
28.4.12
SMBus:
I2C_TIMEOUTR register configuration examples
This section is relevant only when SMBus feature is supported. Please refer to
•
Configuring the maximum duration of t
TIMEOUT
to 25 ms:
•
Configuring the maximum duration of t
LOW:SEXT
and t
LOW:MEXT
to 8 ms:
Table 146. Examples of TIMEOUTA settings for various
I2CCLK
frequencies
(max t
TIMEOUT
= 25 ms)
f
I2CCLK
TIMEOUTA[11:0]
bits
TIDLE
bit
TIMEOUTEN
bit
t
TIMEOUT
8 MHz
0x61
0
1
98 x 2048 x 125 ns = 25 ms
16 MHz
0xC3
0
1
196 x 2048 x 62.5 ns = 25 ms
48 MHz
0x249
0
1
586 x 2048 x 20.08 ns = 25 ms
Table 147. Examples of TIMEOUTB settings for various
I2CCLK
frequencies
f
I2CCLK
TIMEOUTB[11:0]
bits
TEXTEN bit
t
LOW:EXT
8 MHz
0x1F
1
32 x 2048 x 125 ns = 8 ms
16 MHz
0x3F
1
64 x 2048 x 62.5 ns = 8 ms
48 MHz
0xBB
1
188 x 2048 x 20.08 ns = 8 ms