XE8805 SEMTECH [Semtech Corporation], XE8805 Datasheet - Page 94

• Manufacturer Part Number: XE8805
• Description: Data Acquisition MCU
• Manufacturer: SEMTECH [Semtech Corporation]

16.4.3
The ADC can be operated in two distinct modes: "continuous-time" and "on-request" modes (selected using the bit
CONT).
In "continuous-time" mode, the input signal is repeatedly converted into digital. After a conversion is finished, a new
one is automatically initiated. The new value is then written in the result register, and the corresponding internal
trigger pulse is generated. This operation is sketched in Figure 16-3. The conversion time in this case is defined as
T
In the "on-request" mode, the internal behaviour of the converter is the same as in the "continuous-time" mode, but
the conversion is initiated on user request (with the START bit). As shown in Figure 16-4, the conversion time is
also T
on a lower frequency clock than the CPU, there might be a small delay (max. 1 cycle of the ADC sampling
frequency) between the writing of the START or CONT bits and the appearance of BUSY flag.
© Semtech 2006
CONV
.
CONV
. Note that the flag is set at the effective start of the conversion. Since the ADC is generally synchronized
Continuous-Time vs. On-Request
RegACOut[15:0]
RegACOut[15:0]
Figure 16-3. ADC "continuous-time" operation
Internal Trig
Ouput Code
Internal Trig
Ouput Code
Figure 16-4. ADC "on-request" operation
Request
START
BUSY
BUSY
IRQ
IRQ
16-8
T
T
CONV
CONV
XE8805/05A
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