Z8F4822AR020SG Datasheet, PDF (184/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
164
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 after each con-
version.
Caution: In CONTINUOUS Mode, you 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 chang-
es 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.
Observe the following procedure for setting up the ADC and initiating continuous conver-
sion:
1. Enable the appropriate 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 the ANAIN[3:0] field to select one of the 12 analog input sources
– Set CONT to 1 to select continuous conversion
– Write to the VREF bit to enable or disable the internal voltage reference generator
– Set CEN to 1 to start the conversions
3. When the first conversion in continuous operation is complete (after 5129 system
clock cycles, plus the 40 cycles required to power up, if necessary), the ADC control
logic performs the following operations:
– CEN resets to 0 to indicate the first conversion is complete. CEN remains 0 for all
subsequent conversions in continuous operation
– An interrupt request is sent to the Interrupt Controller to indicate the conversion is
complete
4. Thereafter, the ADC writes a new 10-bit data result to {ADCD_H[7:0],
ADCD_L[7:6]} every 256 system clock cycles. An interrupt request is sent to the
Interrupt Controller when each conversion is complete.
5. To disable continuous conversion, clear the CONT bit in the ADC Control Register to
0.
PS019924-0113
PRELIMINARY
Operation