Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!®
134
1. Enable the desired analog inputs by configuring the general-purpose I/O pins for
alternate function. This configuration disables the digital input and output drivers.
2. Write to the ADC Control register to configure the ADC and begin the conversion.
The bit fields in the ADC Control register can be written simultaneously:
–
–
–
–
Write to ANAIN[3:0]to select one of the 12 analog input sources.
Clear CONTto 0 to select a single-shot conversion.
Write to VREFto enable or disable the internal voltage reference generator.
Set CENto 1 to start the conversion.
3. CENremains 1 while the conversion is in progress. A single-shot conversion requires
5129 system clock cycles to complete. If a single-shot conversion is requested from an
ADC powered-down state, the ADC uses 40 additional clock cycles to power-up
before beginning the 5129 cycle conversion.
4. When the conversion is complete, the ADC control logic performs the following
operations:
–
–
–
10-bit data result written to {ADCD_H[7:0], ADCD_L[7:6]}.
CENresets to 0 to indicate the conversion is complete.
An interrupt request is sent to the Interrupt Controller.
5. If the ADC remains idle for 160 consecutive system clock cycles, it is automatically
powered-down.
Continuous Conversion
When configured for continuous conversion, the ADC continuously performs an analog-
to-digital conversion on the selected analog input. Each new data value over-writes the
previous value stored in the ADC Data registers. An interrupt is generated only at the end
of the first conversion after enabling.
Caution:
In Continuous mode, users must be aware that ADC updates are limited by
the input signal bandwidth of the ADC and the latency of the ADC and its
digital filter. Step changes at the input are not seen at the next output from
the ADC. The response of the ADC (in all modes) is limited by the input
signal bandwidth and the latency.
The steps for setting up the ADC and initiating continuous conversion are as follows:
1. Enable the desired analog input by configuring the general-purpose I/O pins for
alternate function. This disables the digital input and output driver.
2. Write to the ADC Control register to configure the ADC for continuous conversion.
The bit fields in the ADC Control register may be written simultaneously:
–
Write to ANAIN[3:0]to select one of the 12 analog input sources.
PS017610-0404
Analog-to-Digital Converter
ZILOG [ ZILOG, INC. ]
