P80C557E6 查看數據表（PDF） - Philips Electronics
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P80C557E6 Datasheet PDF : 64 Pages
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Philips Semiconductors
Single-chip 8-bit microcontroller
Product specification
P83C557E6/P80C557E6
6.6.1 Functional Description
Table 9. A/D Special Function Registers
SYMBOL
ADCON
ADPSS
ADRSLn
ADRSH
P5
NAME
A/D control register
Analog port scan–select register
8 A/D result registers, the 8 lower bits (n: 0...7)
A/D result register, the 2 higher bits
Digital input port (shared with analog inputs)
ACCESS
read/write
read/write
read only
read only
read only
A/D Control Register ADCON
The Special Function Register ADCON contains control and status
bits for the A/D Converter peripheral block. The reset value of
ADCON is (00000000). Its hardware address is D7H. ADCON is not
bit addressable.
ADCON (D7H)
7
ADPR1
6
ADPR0
5
ADPOS
4
ADINT
3
ADSST
2
ADCSA
Figure 15. ADC control register.
1
ADSRE
0
ADSFE
Table 10. Description of ADCON bits
SYMBOL
ADCON.7
ADCON.6
BIT
ADPR1
ADPR0
FUNCTION
Control bit for the prescaler.
Control bit for the prescaler.
ADPR1=0 ADPR0=0 Prescaler divides by 2 (default by reset)
ADPR1=0 ADPR0=1 Prescaler divides by 4
ADPR1=1 ADPR0=0 Prescaler divides by 6
ADPR1=1 ADPR0=1 Prescaler divides by 8
ADCON.5
ADCON.4
ADPOS
ADINT
ADPOS is reserved for future use. Must be ‘0’ if ADCON is written.
ADC interrupt flag. This flag is set when all selected analog inputs are converted, as well in continuous scan
as in one–time scan mode. An interrupt is invoked if this interrupt is enabled. ADINT must be cleared by
software. It cannot be set by software.
ADCON.3
ADSST
ADCON.2
ADCSA
ADC start and status. Setting this bit by software or by hardware (via ADEXS input) starts the A/D conversion
of the selected analog inputs. ADSST stays a ‘one’ in continuous scan mode. In one–time scan mode, ADSST
is cleared by hardware when the last selected analog input channel has been converted. As long as ADSST
is ‘1’, new start commands to the ADC–block are ignored.
An A/D conversion in progress is aborted if ADSST is cleared by software.
1 = Continuous scan of the selected analog inputs after a start of an A/D conversion.
0 = One–time scan of the selected analog inputs after a start of an A/D conversion.
ADCON.1
ADSRE
1 = A rising edge at input ADEXS will start the A/D conversion and generate a capture signal.
0 = A rising edge at input ADEXS has no effect.
ADCON.0
ADSFE
1 = A falling edge at input ADEXS will start the A/D conversion and generate a capture signal.
0 = A falling edge at input ADEXS has no effect.
1999 Mar 02
19
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