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MC68340AB16E Datasheet, PDF (360/441 Pages) Motorola, Inc – Integrated Processor with DMA User’s Manual | |||
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Freescale Semiconductor, Inc.
8.3.8 Timer Bypass
In this mode, the counter and prescaler cannot be enabled. However TGATEâ and
TOUTx can be used for I/O. This mode can be selected by programming the CR MODE
bits to 111.
TGATEâ can be used as a simple input port when the CR is configured as follows:
CR
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
SWR IE2
IE1
IE0 TGE PCLK CPE CLK POT2 POT1 POT0 MODE2 MODE1 MODE0 OC1 OC0
TGATEâ AS A SIMPLE INPUT
X
X
0
X
X
X
1
X
X
X
X
1
1
1
X
X
X-Donât care
When TGATEâ is asserted, the SR ON bit is set. When TGATEâ is negated, the ON bit is
cleared. The value of the TGL bit in the SR reflects the level of TGATEâ. TGATEâ can
also be used as an input port that generates interrupts on a low-to-high transition of
TGATEâ when the CR is configured as follows:
CR
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
SWR IE2
IE1
IE0
TGE PCLK CPE CLK POT2 POT1 POT0 MODE2 MODE1 MODE0 OC1 OC0
TGATEâ AS AN INPUT/INTERRUPT
X
X
1
X
1
X
1
X
X
X
X
1
1
1
X
X
When TGATEâ is negated, the SR TG bit is set, and the programmed IRQx signal is
asserted to the CPU32. The TG bit can only be cleared by writing a one to this bit position.
The value of the SR TGL bit reflects the level of TGATEâ.
Additionally, TOUTx can be used as a simple output port when the CR is configured as
follows:
CR
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
SWR IE2
IE1
IE0
TGE PCLK CPE CLK POT2 POT1 POT0 MODE2 MODE1 MODE0 OC1 OC0
TGATEâ AS A SIMPLE OUTPUT
0
X
X
X
X
X
1
X
X
X
X
1
1
1
OC1 OC0
SWR must be a zero to change the value of TOUTx. Changing the value of the CR OCx
bits determines the level of TOUTx as shown in Table 8-1.
8-16
MC68340 USERâS MANUAL
For More Information On This Product,
Go to: www.freescale.com
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