ADUC831 Analog Devices, ADUC831 Datasheet - Page 26

• Manufacturer Part Number: ADUC831
• Description: Precision Analog Microcontroller: 1.3MIPS 8052 MCU + 62kB Flash + 8-Ch 12-Bit ADC + Dual 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC831

• Mcu Core: 8052
• Mcu Speed (mips): 1.3
• Sram (bytes): 2304Bytes
• Gpio Pins: 34
• Adc # Channels: 8
• Other: PWM

ADuC831
INITIATING CALIBRATION IN CODE
When calibrating the ADC, using ADCCON1 the ADC should
be set up into the configuration in which it will be used. The
ADCCON3 register can then be used to set the device up and
calibrate the ADC offset and gain.
MOV ADCCON1,#08CH
To calibrate device offset:
MOV ADCCON2,#0BH
MOV ADCCON3,#25H
To calibrate device gain:
MOV ADCCON2,#0CH
MOV ADCCON3,#27H
To calibrate system offset:
Connect system AGND to an ADC channel input (0).
MOV ADCCON2,#00H
MOV ADCCON3,#25H
;ADC on; ADCCLK set
;to divide by 16, 4
;acquisition clock
;select internal AGND
;select offset calibration,
;31 averages per bit,
;offset calibration
;select internal VREF
;select offset calibration,
;31 averages per bit,
;offset calibration
;select external AGND
;select offset calibration,
;31 averages per bit
–26–
To calibrate system gain:
Connect system V
MOV ADCCON2,#01H
MOV ADCCON3,#27H
The calibration cycle time, T
equation assuming a 16 MHz crystal:
For an ADCCLK/F
NUMAV = 15, the calibration cycle time is:
In a calibration cycle the ADC busy flag (Bit 7), instead of
framing an individual ADC conversion as in normal mode, will
go high at the start of calibration and only return to zero at the
end of the calibration cycle. It can therefore be monitored in
code to indicate when the calibration cycle is completed. The
following code can be used to monitor the BUSY signal during
a calibration cycle:
WAIT:
MOV A, ADCCON3
JB ACC.7, WAIT
T
CAL
T
T
CAL
CAL
=
14
=
=
14
4 2
×
REF
.
CORE
ADCCLK
×
ms
to an ADC channel input (1).
( /
1 1000000
divide ratio of 16, a T
;move ADCCON3 to A
;If Bit 7 is set jump to
;select external VREF
;select offset calibration,
;31 averages per bit,
;offset calibration
WAIT else continue
CAL
×
, is calculated by the following
NUMAV
)
×
15
×
×
ACQ
(
16
(
16 4
= 4 ADCCLK,
+
+
T
ACQ
)
REV. 0
)