SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 82

• Manufacturer Part Number: SAB80C517-M16
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

7.4
The SAB 80C517 provides an A/D converter with the following features:
For the conversion, the method of successive approximation via capacitor array is used. The
externally applied reference voltage range has to be held on a fixed value within the specifications
(see section "A/D Converter Characteristics" in the data sheet). The internal reference voltages can
be varied to reduce the reference voltage range of the A/D converter and thus to achieve a higher
resolution.
Figure 7-25 shows a block diagram of the A/D converter. There are four user-accessible special
function registers: ADCON0, ADCON1 (A/D converter control registers), ADDAT (A/D converter
data register) and DAPR (D/A converter program register) for the programmable reference
voltages. The analog input channels (port 7 and port 8) can also be used for digital input; refer also
to section 7.1 "Parallel I/O".
7.4.1
7.4.1.1 lnitialization and Input Channel Selection
Special function register ADCON0 which is illustrated in figure 7-26 is used to set the operating
modes, to check the status, and to select one of eight analog input channels. Special function
register ADCON1 (figure 7-27) controls the selection of all twelve input channels.
Register ADCON0 contains two mode bits. Bit ADM is used to choose the single or continuous
conversion mode. In single conversion mode only one conversion is performed after starting, while
in continuous conversion mode after the first start a new conversion is automatically started on
completion of the previous one.
Semiconductor Group
– 12 multiplexed input channels, which can also be used as digital inputs (port 7, port 8)
– Programmable internal reference voltages (16 steps each) via resistor array
– 8-bit resolution within the selected reference voltage range
– 13 microseconds conversion time (including sample time) at 12-MHz oscillator frequency
– Selectable external or internal start-of-conversion trigger
– Interrupt request generation after each conversion
A/D Converter
Function and Control
83
On-Chip Peripheral Components