Figure 38. ADC Description
ADCON.5
ADCON.3
ADEN
ADSST
ADCON.4
ADC
Interrupt
Request
ADEOC
ADC
CLOCK
CONTROL
EADC
IEN1.1
AN0/P1.0
AN1/P1.1
AN2/P1.2
AN3/P1.3
AN4/P1.4
AN5/P1.5
AN6/P1.6
AN7/P1.7
000
001
010
011
100
101
110
111
8
2
Rai
Cai
ADCIN
ADDH
ADDL
+
-
SAR
AVSS
Sample and Hold
10
R/2R DAC
SCH2
SCH1
SCH0
VAREF VAGND
ADCON.2 ADCON.1 ADCON.0
Figure 39 shows the timing diagram of a complete conversion. For simplicity, the figure
depicts the waveforms in idealized form and do not provide precise timing information.
For ADC characteristics and timing parameters refer to the section “AC Characteristics”
of this datasheet.
Figure 39. Timing Diagram
CLK
ADEN
TSETUP
ADSST
ADEOC
TCONV
Note:
Tsetup min, see the AC Parameter for A/D conversion.
Tconv = 11 clock ADC = 1sample and hold + 10-bit conversion
The user must ensure that Tsetup time between setting ADEN and the start of the first conversion.
ADC Converter
Operation
A start of single A/D conversion is triggered by setting bit ADSST (ADCON.3).
After completion of the A/D conversion, the ADSST bit is cleared by hardware.
The end-of-conversion flag ADEOC (ADCON.4) is set when the value of conversion is
available in ADDH and ADDL, it must be cleared by software. If the bit EADC (IEN1.1) is
set, an interrupt occur when flag ADEOC is set (See Figure 41). Clear this flag for re-
arming the interrupt.
Note:
Always leave Tsetup time before starting a conversion unless ADEN is permanently high.
In this case one should wait Tsetup only before the first conversion
84
AT89C5115
4128F–8051–05/06
ATMEL [ ATMEL ]
