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RM0313 Datasheet, PDF (583/900 Pages) STMicroelectronics – This reference manual targets application developers
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RM0313
Inter-integrated circuit (I2C) interface
24.4.9
I2C_TIMINGR register configuration examples
The tables below provide examples of how to program the I2C_TIMINGR to obtain timings
compliant with the I2C specification. In order to get more accurate configuration values,
please refer to application note AN4235 I2C timing configuration tool and the associated
software STSW-STM32126.
Parameter
Table 71. Examples of timings settings for fI2CCLK = 8 MHz
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
tSCLL
SCLH
200x250 ns = 50 µs
0xC3
20x250 ns = 5.0 µs
0xF
10x125 ns = 1250 ns
0x3
7x125 ns = 875 ns
0x3
tSCLH
tSCL(1)
SDADEL
196x250 ns = 49 µs
~100 µs(2)
0x2
16x250 ns = 4.0µs
~10 µs(2)
0x2
4x125ns = 500ns
~2500 ns(3)
0x1
4x125 ns = 500 ns
~2000 ns(4)
0x0
tSDADEL
2x250 ns = 500 ns
2x250 ns = 500 ns
1x125 ns = 125 ns
0 ns
SCLDEL
0x4
0x4
0x3
0x1
tSCLDEL
5x250 ns = 1250 ns 5x250 ns = 1250 ns
4x125 ns = 500 ns
2x125 ns = 250 ns
1.
SCL
only.
period
tSCL
is
greater
than
tSCLL
+
tSCLH
due
to
SCL
internal
detection
delay.
Values
provided
for
tSCL
are
examples
2. tSYNC1 + tSYNC2 minimum value is 4 x tI2CCLK = 500 ns. Example with tSYNC1 + tSYNC2 = 1000 ns
3. tSYNC1 + tSYNC2 minimum value is 4 x tI2CCLK = 500 ns. Example with tSYNC1 + tSYNC2 = 750 ns
4. tSYNC1 + tSYNC2 minimum value is 4 x tI2CCLK = 500 ns. Example with tSYNC1 + tSYNC2 = 655 ns
Parameter
PRESC
SCLL
tSCLL
SCLH
tSCLH
tSCL(1)
SDADEL
tSDADEL
SCLDEL
tSCLDEL
Table 72. Examples of timings settings for fI2CCLK = 16 MHz
Standard-mode (Sm)
Fast-mode (Fm)
Fast-mode Plus (Fm+)
10 kHz
3
0xC7
200 x 250 ns = 50 µs
0xC3
196 x 250 ns = 49 µs
~100 µs(2)
0x2
2 x 250 ns = 500 ns
0x4
5 x 250 ns = 1250 ns
100 kHz
3
0x13
20 x 250 ns = 5.0 µs
0xF
16 x 250 ns = 4.0 µs
~10 µs(2)
0x2
2 x 250 ns = 500 ns
0x4
5 x 250 ns = 1250 ns
400 kHz
1
0x9
10 x 125 ns = 1250 ns
0x3
4 x 125ns = 500 ns
~2500 ns(3)
0x2
2 x 125 ns = 250 ns
0x3
4 x 125 ns = 500 ns
1000 kHz
0
0x4
5 x 62.5 ns = 312.5 ns
0x2
3 x 62.5 ns = 187.5 ns
~1000 ns(4)
0x0
0 ns
0x2
3 x 62.5 ns = 187.5 ns
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