mc68hc05l25 Freescale Semiconductor, Inc, mc68hc05l25 Datasheet - Page 83

• Manufacturer Part Number: mc68hc05l25
• Description: M68hc05 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 9
Time Base
9.1 Introduction
Time base is a 14-bit up-counter which is clocked by XOSC.
This 14-bit divider is initialized to $0078 only upon power-on reset (POR). After counting 16,264 clocks,
the STUP bit in the MISC register is set. See
9.2 Time Base Submodules
The clock divided by the time base is used for LCDCLK, STUP, TBI, and COP. The time base clock can
be provided either from OSC or XOSC.
9.2.1 LCDCLK
One of four clock frequency combinations can be selected for the LCD clock.
9.2.2 STUP
The time base divider is initialized to $0078 at power-on, and when the count reaches 16,264, the STUP
flag in the MISC register is set. Once the STUP flag is set, it is never cleared while power is applied.
9.2.3 TBI
Time base interrupt can be generated every 0.5, 0.25, 0.125, or 0.0039 seconds with a 32.768-kHz crystal
at XOSC pins. See
Freescale Semiconductor
TBCLK LCLK
0
0
1
1
TBCR1
Table
0
1
0
1
9-2.
OSC ÷ 8192
XOSC ÷ 64
XOSC ÷ 28
Divide
OSC ÷
16,384
Ratio
Table 9-1. LCD Clock Frequency
MC68HC05L25 Data Sheet, Rev. 3.1
OSC = 2.0 MHz
Figure 8-4
512
256
244
122
LCD Clock Frequency (Hz)
for more information.
(f
OSC = 4.0 MHz
XOSC
512
256
488
244
= 32.768 kHz)
OSC = 4.1943 MHz
512
256
512
256
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