MC908JL16CFAE FREESCALE [Freescale Semiconductor, Inc], MC908JL16CFAE Datasheet - Page 132

• Manufacturer Part Number: MC908JL16CFAE
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Analog-to-Digital Converter (ADC)
COCO — Conversion Complete Bit
AIEN — ADC10 Interrupt Enable Bit
ADCO — ADC10 Continuous Conversion Bit
ADCH[4:0] — Channel Select Bits
132
The COCO bit is a read-only bit which is set each time a conversion is completed. This bit is cleared
whenever the status and control register is written or whenever the data register (low) is read.
When this bit is set, an interrupt is generated at the end of a conversion. The interrupt signal is cleared
when the data register is read or the status/control register is written. Reset clears the AIEN bit.
When written high, the ADC10 will begin to convert samples continuously (continuous conversion
mode) and update the result registers at the end of each conversion, provided the ADCH[4:0] bits do
not decode to all 1s. The ADC10 will continue to convert until the MCU enters reset, the MCU enters
stop mode (if ACLKEN is clear), the ADCLK register is written, or until the ADCSC is written again. If
Stop is entered (with ACLKEN low), continuous conversions will cease and can only be restarted with
a write to the ADCSC. Any write to the ADCSC with the ADCO bit set and the ADCH bits not all 1s will
abort the current conversion and begin continuous conversions.
If the bus frequency is less than the ADCK frequency, precise sample time for continuous conversions
cannot be guaranteed in short-sample mode (ADLSMP = 0). If the bus frequency is less than 1/11th
of the ADCK frequency, precise sample time for continuous conversions cannot be guaranteed in
long-sample mode (ADLSMP = 1).
When clear, the ADC10 will perform a single conversion (single conversion mode) each time the
ADCSC is written (assuming the ADCH[4:0] bits do not decode all 1s). Reset clears the ADCO bit.
ADCH4, ADCH3, ADCH2, ADCH1, and ADCH0 form a 5-bit field which is used to select one of the
input channels. The input channels are detailed in
The successive approximation converter subsystem is turned off when the channel select bits are all
set to 1. This feature allows for explicit disabling of the ADC10 and isolation of the input channel from
the I/O pad. Terminating continuous convert mode this way will prevent an additional, single
conversion from being performed. It is not necessary to set the channel select bits to all 1s to place the
ADC10 in a low-power state, however, because the module is automatically placed in a low-power
state when a conversion completes.
1 = Conversion completed
0 = Conversion not completed
1 = ADC10 interrupt enabled
0 = ADC10 interrupt disabled
1 = Continuous conversion following a write to the ADCSC
0 = One conversion following a write to the ADCSC
MC68HC908JL16 Data Sheet, Rev. 1.1
Table
9-2.
Freescale Semiconductor