ML63611 User’s Manual
Chapter 16 A/D Converter (ADC)
16 – 16
OPTION B (D): 1.5 V (3.0 V), With regulator
circuit for LCD bias
OPTION A (C): 1.5 V (3.0 V), Without regulator
circuit for LCD bias
⑩
Write “7H” to ADCON0 and start A/D conversion in Counter B reference mode.
Note:
Since the setting of STV = 1 has already been made in the preprocessing, there is no need to wait for 120
µ
s.
Execute the HALT instruction to enter the halt mode.
The RC oscillation circuit (CROSC0) oscillates with thermistor RT0 from this time until overflow of Counter B.
This period is equivalent to product of “nB0” from first step and t
OSCCLK
(RT0) due to RT0.
When Counter B overflows, the ADINT signal is set to “1” and the A/D converter interrupt request is generated
([d]). By the generation of the interrupt request, halt mode is released ([e]) and the A/D conversion operation is
stopped ([f]; the EADC bit = “0”). The contents of Counter A becomes the A/D conversion value of nA1 and is
expressed by the following:
nA1 = nB0 • - - - - - equation (c)
By equations (b) and (c), nA1 is expressed as
nA1 = nA0 • - - - - - equation (d)
where t
OSCCLK
(RS0) is the period of the oscillation clock by reference resistance RS0 and t
OSCCLK
(RT0) is the
period of the oscillation clock by thermistor RT0.
The oscillation period is expressed ideally as
t
OSCCLK
(RS0) = k
OSCCLK
• CS0 • RS0
- - - - - equation (e)
t
OSCCLK
(RT0) = k
OSCCLK
• CS0 • RT0
By substituting equation (e) to equation (d), nA1 is expressed as
nA1 = nA0 •
As “nA0” (12,000 in this example) and RS0 are fixed constants, “nA1” becomes a digital value proportional to
RT0. This “nA1” is equivalent to “nT0” in equation (a).
The obtained “nA1” must be further converted to a temperature display value depending on the temperature-
resistance characteristics of the thermistor in a program.
!
t
OSCCLK
(RT0)
t
SYSCLK
t
OSCCLK
(RT0)
t
OSCCLK
(RS0)
RT0
RS0
11
Содержание ML63611
Страница 9: ...Chapter 1 Overview...
Страница 33: ...Chapter 2 CPU and Memory Spaces...
Страница 42: ...Chapter 3 CPU Control Functions...
Страница 49: ...Chapter 4 Interrupt INT...
Страница 62: ...Chapter 5 Clock Generator Circuit OSC...
Страница 71: ...Chapter 6 Time Base Counter TBC...
Страница 75: ...Chapter 7 Timers TIMER...
Страница 99: ...Chapter 8 100 Hz Timer Counter 100HzTC...
Страница 103: ...Chapter 9 Watchdog Timer WDT...
Страница 108: ...Chapter 10 Ports INPUT I O PORT...
Страница 140: ...Chapter 11 Melody Driver MELODY...
Страница 152: ...Chapter 12 Serial Port SIO...
Страница 179: ...Chapter 13 LCD Driver LCD...
Страница 200: ...Chapter 14 Battery Low Detect Circuit BLD...
Страница 204: ...Chapter 15 Power Supply Circuit POWER...
Страница 215: ...Chapter 16 A D Converter ADC...
Страница 238: ...Appendixes...
Страница 271: ...ML63611 User s Manual First Edition May 2001 Second Edition June 2001 2001 Oki Electric Industry Co Ltd PEUL63611 02...