TM4C1233H6PZIR Datasheet, PDF (989/1233 Pages) Texas Instruments – Tiva TM4C1233H6PZ Microcontroller

Tiva^™ TM4C1233H6PZ Microcontroller _{(identical to LM4F122H5QC)}
16.3.2
Available Speed Modes
The I²C bus can run in Standard mode (100 kbps), Fast mode (400 kbps), Fast mode plus (1 Mbps)
or High-Speed mode (3.33 Mbps). The selected mode should match the speed of the other I²C
devices on the bus.
16.3.2.1
Standard, Fast, and Fast Plus Modes
Standard, Fast, and Fast Plus modes are selected using a value in the I²C Master Timer Period
(I2CMTPR) register that results in an SCL frequency of 100 kbps for Standard mode, 400 kbps for
Fast mode, or 1 Mbps for Fast mode plus.
The I²C clock rate is determined by the parameters CLK_PRD, TIMER_PRD, SCL_LP, and SCL_HP
where:
CLK_PRD is the system clock period
SCL_LP is the low phase of SCL (fixed at 6)
SCL_HP is the high phase of SCL (fixed at 4)
TIMER_PRD is the programmed value in the I2CMTPR register (see page 1011). This value is
determined by replacing the known variables in the equation below and solving for TIMER_PRD.
The I²C clock period is calculated as follows:
SCL_PERIOD = 2 × (1 + TIMER_PRD) × (SCL_LP + SCL_HP) × CLK_PRD
For example:
CLK_PRD = 50 ns
TIMER_PRD = 2
SCL_LP=6
SCL_HP=4
yields a SCL frequency of:
1/SCL_PERIOD = 333 Khz
Table 16-2 gives examples of the timer periods that should be used to generate Standard, Fast
mode, and Fast mode plus SCL frequencies based on various system clock frequencies.
Table 16-2. Examples of I²C Master Timer Period versus Speed Mode
System Clock Timer Period Standard Mode Timer Period Fast Mode
4 MHz
6 MHz
12.5 MHz
16.7 MHz
20 MHz
25 MHz
33 MHz
40 MHz
50 MHz
80 MHz
0x01
0x02
0x06
0x08
0x09
0x0C
0x10
0x13
0x18
0x27
100 Kbps
100 Kbps
89 Kbps
93 Kbps
100 Kbps
96.2 Kbps
97.1 Kbps
100 Kbps
100 Kbps
100 Kbps
-
-
0x01
0x02
0x02
0x03
0x04
0x04
0x06
0x09
-
-
312 Kbps
278 Kbps
333 Kbps
312 Kbps
330 Kbps
400 Kbps
357 Kbps
400 Kbps
Timer
Period
-
-
-
-
-
-
-
0x01
0x02
0x03
Fast Mode
Plus
-
-
-
-
-
-
-
1000 Kbps
833 Kbps
1000 Kbps
July 17, 2013
989
Texas Instruments-Production Data