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RM0365
Inter-integrated circuit (I2C) interface
834
28.4.9 I2C_TIMINGR
register configuration examples
The tables below provide examples of how to program the I2C_TIMINGR to obtain timings
compliant with the I
2
C specification. In order to get more accurate configuration values,
please refer to the application note:
I
2
C timing configuration tool
(AN4235)
and the
associated software STSW-STM32126.
Table 141. Examples of timings settings for f
I2CCLK
= 8 MHz
Parameter
Standard-mode (Sm)
Fast-mode (Fm)
Fast-mode Plus (Fm+)
10 kHz
100 kHz
400 kHz
500 kHz
PRESC
1
1
0
0
SCLL
0xC7
0x13
0x9
0x6
t
SCLL
200x250 ns = 50 µs
20x250 ns = 5.0 µs
10x125 ns = 1250 ns
7x125 ns = 875 ns
SCLH
0xC3
0xF
0x3
0x3
t
SCLH
196x250 ns = 49 µs
16x250 ns = 4.0µs
4x125ns = 500ns
4x125 ns = 500 ns
t
SCL
(1)
~100 µs
(2)
~10 µs
~2500 ns
(3)
~2000 ns
(4)
SDADEL
0x2
0x2
0x1
0x0
t
SDADEL
2x250 ns = 500 ns
2x250 ns = 500 ns
1x125 ns = 125 ns
0 ns
SCLDEL
0x4
0x4
0x3
0x1
t
SCLDEL
5x250 ns = 1250 ns
5x250 ns = 1250 ns
4x125 ns = 500 ns
2x125 ns = 250 ns
1. SCL period t
SCL
is greater than t
SCLL
+ t
SCLH
due to SCL internal detection delay. Values provided for t
SCL
are examples
only.
2. t
SYNC1
+
t
SYNC2
minimum value is 4 x t
I2CCLK
= 500 ns. Example with t
SYNC1
+
t
SYNC2
= 1000 ns
3. t
SYNC1
+
t
SYNC2
minimum value is 4 x t
I2CCLK
= 500 ns. Example with t
SYNC1
+
t
SYNC2
= 750 ns
4. t
SYNC1
+
t
SYNC2
minimum value is 4 x t
I2CCLK
= 500 ns. Example with t
SYNC1
+ t
SYNC2
= 655 ns
Table 142. Examples of timings settings for f
I2CCLK
= 16 MHz
Parameter
Standard-mode (Sm)
Fast-mode (Fm)
Fast-mode Plus (Fm+)
10 kHz
100 kHz
400 kHz
1000 kHz
PRESC
3
3
1
0
SCLL
0xC7
0x13
0x9
0x4
t
SCLL
200 x 250 ns = 50 µs
20 x 250 ns = 5.0 µs
10 x 125 ns = 1250 ns
5 x 62.5 ns = 312.5 ns
SCLH
0xC3
0xF
0x3
0x2
t
SCLH
196 x 250 ns = 49 µs
16 x 250 ns = 4.0 µs
4 x 125ns = 500 ns
3 x 62.5 ns = 187.5 ns
t
SCL
(1)
~100 µs
(2)
~2500 ns
(3)
~1000 ns
(4)
SDADEL
0x2
0x2
0x2
0x0
t
SDADEL
2 x 250 ns = 500 ns
2 x 250 ns = 500 ns
2 x 125 ns = 250 ns
0 ns
SCLDEL
0x4
0x4
0x3
0x2
t
SCLDEL
5 x 250 ns = 1250 ns
5 x 250 ns = 1250 ns
4 x 125 ns = 500 ns
3 x 62.5 ns = 187.5 ns