MC68HC711G5 MOTOROLA [Motorola, Inc], MC68HC711G5 Datasheet - Page 75

• Manufacturer Part Number: MC68HC711G5
• Description: High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcontroller
• Manufacturer: MOTOROLA [Motorola, Inc]

MC68HC11G5
6.4.1
READ:
WRITE:
RESET:
READ:
WRITE:
RESET:
TCNT1 is associated with OC1 – OC4, OC5/IC4 and OC6/IC5. Note thatdue to the periodic interrupt
and COP timer also using this counter as their clock source, an external clock cannot be used to
drive this timer counter.
TCNT2 is associated with IC1 – IC3 and OC7/IC6. This counter differs from counter 1 in two ways:
it can be driven by an external clock; and it can be reset under software control.
A full counter read should first address the most significant byte. Reading this address causes the
least significant byte to be latched into a buffer for the next CPU cycle so that a double byte read
will return the full 16-bit state of the counter at the time of the most significant byte read cycle. This
buffer is not affected by reset and is accessed when reading the least significant byte of the counter.
For double byte read instructions, these two accesses occur on consecutive bus cycles. The buffer
is transparent except for the cycle following a most significant byte read so that reads of the least
significant byte alone will return the current state of the counter. Software can read the counter at
any time without affecting its value. Note that the counter is clocked and read during opposite half
cycles of the E-clock.
Both counters are cleared to $0000 during reset. In the normal operating modes (SMOD = 0), writing
to TCNT2 causes TCNT2 to be reset to $0000, whereas writing to TCNT1 has no effect. In the test
and bootstrap modes only (SMOD = 1), any write to either counter’s most significant byte causes
6.4
TIMER, RTI AND PULSE ACCUMULATOR REGISTERS
Count Registers (TCNT1 and TCNT2)
RESET:
RESET:
Any time.
Has no effect for SMOD = 0; forces to $FFF8 for SMOD = 1.
$0000.
Any time.
Forces to $0000 for SMOD = 0; forces to $FFF8 for SMOD = 1.
$0000.
$100E
$100F
$1052
$1053
BIT15
BIT15
BIT7
BIT7
7
0
0
7
0
0
BIT14
BIT14
BIT6
BIT6
6
0
0
6
0
0
BIT13
BIT13
BIT5
BIT5
PROGRAMMABLE TIMER
5
0
0
5
0
0
BIT12
BIT12
BIT4
BIT4
4
0
0
4
0
0
BIT11
BIT11
BIT3
BIT3
3
0
0
3
0
0
BIT10
BIT10
BIT2
BIT2
2
0
0
2
0
0
BIT9
BIT1
BIT9
BIT1
1
0
0
1
0
0
BIT8
BIT0
BIT8
BIT0
0
0
0
0
0
0
TCNT1
TCNT2
MOTOROLA
6-5