MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 625

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

17.3.9 Prescaler Control for TCR2
MPC555
USER’S MANUAL
Timer count register 2 (TCR2), like TCR1, is clocked from the output of a prescaler.
The T2CG (TCR2 clock/gate control) bit and the T2CSL (TCR2 counter clock edge) bit
in TPUMCR determine T2CR2 pin functions. Refer to
The function of the T2CG bit is shown in
When T2CG is set, the external T2CLK pin functions as a gate of the DIV8 clock (the
TPU3 IMB clock divided by eight). In this case, when the external TCR2 pin is low, the
DIV8 clock is blocked, preventing it from incrementing TCR2. When the external TCR2
pin is high, TCR2 is incremented at the frequency of the DIV8 clock. When T2CG is
cleared, an external clock from the TCR2 pin, which has been synchronized and fed
through a digital filter, increments TCR2. The duration between active edges on the
T2CLK clock pin must be at least nine IMB clocks.
The TCR2PSCK2 bit in TPUMCR3 determines whether the clock source is divided by
two before it is fed into the TCR2 prescaler. The TCR2 field in TPUMCR specifies the
value of the prescaler: 1, 2, 4, or 8. Channels using TCR2 have the capability to re-
DIV2
IMB
Clock
EPSCKE
/
MPC556
T2CSL
Enhanced
Table 17-3 TCR2 Counter Clock Source
Prescaler
2,4,6,...64
0
0
1
1
Prescaler
Figure 17-3 TCR1 Prescaler Control
32 / 4
TIME PROCESSOR UNIT 3
Rev. 15 October 2000
T2CG
PSCK
MUX
0
1
0
1
Figure
Rise & fall transition T2CLK
Rise transition T2CLK
Fall transition T2CLK
17-4.
Gated IMB clock
TCR2 Clock
PRESCALER
1,2,4,8
TCR1
Table
17-3.
TCR1
MOTOROLA
17-7