MC68332
REGISTER SUMMARY
USER’S MANUAL
D-31
TCR2P — Timer Count Register 2 Prescaler Control
TCR2 is clocked from the output of a prescaler. If T2CG = 0, the input to the TCR2
prescaler is the external TCR2 clock source. If T2CG = 1, the input is the TPU system
clock divided by eight. The TCR2 field specifies the value of the prescaler: 1, 2, 4, or
8. Channels using TCR2 have the capability to resolve down to the TPU system clock
divided by 8. The following table is a summary of prescaler output.
EMU — Emulation Control
In emulation mode, the TPU executes microinstructions from MCU TPURAM exclu-
sively. Access to the TPURAM module through the IMB by a host is blocked, and the
TPURAM module is dedicated for use by the TPU. After reset, this bit can be written
only once.
0 = TPU and TPURAM not in emulation mode
1 = TPU and TPURAM in emulation mode
T2CG — TCR2 Clock/Gate Control
When the T2CG bit is set, the external TCR2 pin functions as a gate of the DIV8 clock
(the TPU system 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 exter-
nal 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.
0 = TCR2 pin used as clock source for TCR2
1 = TCR2 pin used as gate of DIV8 clock for TCR2
STF — Stop Flag
0 = TPU operating
1 = TPU stopped (STOP bit has been asserted)
SUPV — Supervisor/Unrestricted
0 = Supervisor access
1 = User access
PSCK = 0
PSCK = 1
TCR1 Prescaler
Divide
By
Number of
Clocks
Rate at
16 MHz
Number of
Clocks
Rate at
16 MHz
00
1
32
2 ms
4
250 ns
01
2
64
4 ms
8
500 ns
10
4
128
8 ms
16
1 ms
11
8
256
16 ms
32
2 ms
TCR2 Prescaler
Divide By
Internal Clock
Divided By
External Clock
Divided By
00
1
8
1
01
2
16
2
10
4
32
4
11
8
64
8
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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