MC908GR32AVFAE Datasheet, PDF (63/314 Pages) Freescale Semiconductor, Inc – Microcontrollers

Monotonicity
NOTE
Quantization error is affected when only the most significant eight bits are
used as a result. See Figure 3-3.
8-BIT 10-BIT
RESULT RESULT
003
00B
IDEAL 8-BIT CHARACTERISTIC
WITH QUANTIZATION = ±1/2
10-BIT TRUNCATED
TO 8-BIT RESULT
00A
IDEAL 10-BIT CHARACTERISTIC
009 WITH QUANTIZATION = ±1/2
002
008
007
006
005
001
004
003
002
WHEN TRUNCATION IS USED,
ERROR FROM IDEAL 8-BIT = 3/8 LSB
DUE TO NON-IDEAL QUANTIZATION.
001
000
000
1/2
2 1/2
4 1/2
6 1/2
8 1/2
INPUT VOLTAGE
1 1/2
3 1/2
5 1/2
7 1/2
9 1/2
REPRESENTED AS 10-BIT
INPUT VOLTAGE
1/2
1 1/2
2 1/2
REPRESENTED AS 8-BIT
Figure 3-3. Bit Truncation Mode Error
3.4 Monotonicity
The conversion process is monotonic and has no missing codes.
3.5 Interrupts
When the AIEN bit is set, the ADC module is capable of generating CPU interrupts after each ADC
conversion. A CPU interrupt is generated if the COCO bit is a 0. The COCO bit is not used as a conversion
complete flag when interrupts are enabled.
3.6 Low-Power Modes
The WAIT and STOP instruction can put the MCU in low power- consumption standby modes.
3.6.1 Wait Mode
The ADC continues normal operation during wait mode. Any enabled CPU interrupt request from the ADC
can bring the MCU out of wait mode. If the ADC is not required to bring the MCU out of wait mode, power
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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