PWMs and timers
CAN_RX
CAN receive
data pin
T
WAKEUP
(Input)
Figure 21. Bus Wake-up Detection
8.7.4 Inter-Integrated Circuit Interface (I2C) Timing
Table 35. I 2C Timing
Characteristic
Symbol
Standard Mode
Minimum Maximum
100
Fast Mode
Minimum Maximum
Unit
SCL Clock Frequency
fSCL
0
0
400
—
kHz
µs
Hold time (repeated) START condition.
After this period, the first clock pulse is
generated.
tHD; STA
4
—
0.6
LOW period of the SCL clock
HIGH period of the SCL clock
tLOW
tHIGH
4.7
4
—
—
—
1.3
0.6
0.6
—
—
—
µs
µs
µs
Set-up time for a repeated START
condition
tSU; STA
4.7
Data hold time for I2C bus devices
Data set-up time
tHD; DAT
tSU; DAT
tr
01
2504
—
3.452
—
03
1002, 5
20 +0.1Cb
20 +0.1Cb
0.6
0.91
—
µs
ns
ns
ns
µs
µs
6
5
Rise time of SDA and SCL signals
Fall time of SDA and SCL signals
Set-up time for STOP condition
1000
300
—
300
300
—
tf
—
tSU; STO
tBUF
4
Bus free time between STOP and
START condition
4.7
—
1.3
—
Pulse width of spikes that must be
suppressed by the input filter
tSP
N/A
N/A
0
50
ns
1. The master mode I2C deasserts ACK of an address byte simultaneously with the falling edge of SCL. If no slaves
acknowledge this address byte, a negative hold time can result, depending on the edge rates of the SDA and SCL lines.
2. The maximum tHD; DAT must be met only if the device does not stretch the LOW period (tLOW) of the SCL signal.
3. Input signal Slew = 10ns and Output Load = 50pf
4. Set-up time in slave-transmitter mode is 1 IPBus clock period, if the TX FIFO is empty.
5. A Fast mode I2C bus device can be used in a Standard mode I2C bus system, but the requirement tSU; DAT ≥ 250 ns must
then be met. This is automatically the case if the device does not stretch the LOW period of the SCL signal. If such a
device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line trmax + tSU; DAT
1000 + 250 = 1250 ns (according to the Standard mode I2C bus specification) before the SCL line is released.
6. Cb = total capacitance of the one bus line in pF.
=
MC56F844xx Advance Information Data Sheet, Rev. 2, 06/2012.
Freescale Semiconductor, Inc.
57
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