MC68HC908AB32 Datasheet, PDF (212/392 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Timer Interface Module B (TIMB)
PS[2:0] — Prescaler Select Bits
These read/write bits select either the PTD4/TBCLK pin or one of the
seven prescaler outputs as the input to the TIMB counter as
Table 12-2 shows. Reset clears the PS[2:0] bits.
Table 12-2. Prescaler Selection
PS2 PS1 PS0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
TIM Clock Source
Internal Bus Clock ÷1
Internal Bus Clock ÷ 2
Internal Bus Clock ÷ 4
Internal Bus Clock ÷ 8
Internal Bus Clock ÷ 16
Internal Bus Clock ÷ 32
Internal Bus Clock ÷ 64
PTD4/TBCLK
12.10.2 TIMB Counter Registers
The two read-only TIMB counter registers contain the high and low bytes
of the value in the TIMB counter. Reading the high byte (TBCNTH)
latches the contents of the low byte (TBCNTL) into a buffer. Subsequent
reads of TBCNTH do not affect the latched TBCNTL value until TBCNTL
is read. Reset clears the TIMB counter registers. Setting the TIMB reset
bit (TRST) also clears the TIMB counter registers.
NOTE:
If you read TBCNTH during a break interrupt, be sure to unlatch TBCNTL
by reading TBCNTL before exiting the break interrupt. Otherwise,
TBCNTL retains the value latched during the break.
Address: $0041
Bit 7
6
5
4
3
2
1
Bit 0
Read: Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 12-5. TIMB Counter Register High (TBCNTH)
Technical Data
212
Timer Interface Module B (TIMB)
MC68HC908AB32 — Rev. 1.1
Freescale Semiconductor