P8XCL580HFT View Datasheet(PDF) - Philips Electronics
Part Name
Description
MFG CO.
'P8XCL580HFT' PDF : 80 Pages View PDF
Philips Semiconductors
Low voltage 8-bit microcontrollers with
UART, I2C-bus and ADC
Product specification
P80CL580; P83CL580
13 ANALOG-TO-DIGITAL CONVERTER (ADC)
The analog input circuitry consists of a 4-bit analog
multiplexer and an ADC with 8-bit resolution. The analog
reference voltage (Vref(p)(A)) and analog ground (VSSA) are
connected via separate input pins. The conversion is
selectable from 24 machine cycles (24 µs at
fosc = 12 MHz) to 48 machine cycles. The functional
diagram of the ADC is shown in Fig. 14.
The ADC is controlled using the ADC Control Register
(ADCON). Input channels are selected by the analog
multiplexer via the ADCON register bits AADR0 and
AADR1. The completion of the 8-bit ADC conversion is
flagged by ADCI in the ADCON register and the result is
stored in the Special Function Register ADCH (address
C5H).
An ADC conversion in progress is unaffected by an
external software ADC start.
The result of a completed conversion remains unaffected
provided ADCI = 1. While ADCS = 1 or ADCI = 1, a new
ADC start will be blocked and consequently lost.
An ADC conversion already in progress is aborted when
the Power-down mode is entered. The result of a
completed conversion (ADCI = 1) remains unaffected
when entering the Idle or Power-down mode.
The analog-to-digital conversion can be started in 3 ways:
• Start in operating mode, continue in operating mode
• Start in operating mode, by setting the ADCS bit, then go
to Idle mode
• Set the ADEX bit, go to the Idle mode and start
conversion externally via the STADC pin.
For the three cases mentioned above the internal flag
ADCI is set upon completion of the conversion.
handbook, full pagewidth
ADC0
ADC1
ADC2
ADC3
ANALOG INPUT
MULTIPLEXER
START
END
ADCON 0 1 2 3 4 5 6 -
(1)
ADEX
8-BIT ADC
(succesive approximation)
STADC
+ Vref(p)(A)
VSSA
0 1 2 3 4 5 6 7 ADCH
INTERNAL BUS
MGC751
(1) For the descriptions of ADCON bits see Table 10.
Fig.14 Functional diagram of analog input.
1997 Mar 14
23
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