Z8 Encore! XP® 4K Series
Product Specification
117
3. Write the ADC Control/Status Register 1 to configure the ADC
–
Write to BUFMODE[2:0] to select SINGLE-ENDED or DIFFERENTIAL mode, as
well as unbuffered or buffered mode.
–
–
If the alarm function is required, set ALMHENand/or ALMLEN.
Write the REFSELHbit of the pair {REFSELH, REFSELL} to select the internal
voltage reference level or to disable the internal reference. The REFSELLbit is
contained in the ADC Control Register 0.
4. Write to the ADC Control Register 0 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 from the available analog input sources
(different input pins available depending on the device)
–
–
Set CONTto 1 to select continuous conversion.
If the internal VREF must be output to a pin, set the REFEXTbit to 1. The internal
voltage reference must be enabled in this case.
–
Write the REFSELLbit of the pair {REFSELH, REFSELL} to select the internal
voltage reference level or to disable the internal reference. The REFSELHbit is
contained in ADC Control/Status Register 1.
–
Set CENto 1 to start the conversions.
5. When the first conversion in continuous operation is complete (after 5129 system
clock cycles, plus the 40 cycles for power-up, if necessary), the ADC control logic
performs the following operations:
–
CENresets to 0 to indicate the first conversion is complete. CENremains 0 for all
subsequent conversions in continuous operation.
–
An interrupt request is sent to the Interrupt Controller to indicate the conversion is
complete.
6. The ADC writes a new data result every 256 system clock cycles. For each completed
conversion, the ADC control logic performs the following operations:
–
–
Writes the 13-bit two’s complement result to {ADCD_H[7:0], ADCD_L[7:3]}.
If the high and low alarms are disabled, sends an interrupt request to the Interrupt
Controller denoting conversion complete.
–
–
If the high alarm is enabled and the ADC value is higher than the alarm threshold,
generates an interrupt.
If the low alarm is enabled and the ADC value is lower than the alarm threshold,
generates an interrupt.
7. To disable continuous conversion, clear the CONTbit in the ADC Control Register
to 0.
PS022815-0206
Analog-to-Digital Converter
ZILOG [ ZILOG, INC. ]
