SAH-C515 SIEMENS [Siemens Semiconductor Group], SAH-C515 Datasheet - Page 100

• Manufacturer Part Number: SAH-C515
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

6.4
The C515 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 chapter 10). 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 6-30 shows a block diagram of the A/D converter.
6.4.1 A/D Converter Operation
An internal start of a single A/D conversion is triggered by a write-to-DAPR instruction. When single
conversion mode is selected (bit ADM=0) only one A/D conversion is performed. In continuous
mode (bit ADM=1), after completion of an A/D conversion a new A/D conversion is triggered
automatically until bit ADM is reset.
The busy flag BSY (ADCON.4) is automatically set when an A/D conversion is in progress. After
completion of the conversion it is reset by hardware. This flag can be read only, a write has no
effect. The interrupt request flag IADC (IRCON.0) is set when an A/D conversion is completed.
The bits MX0 to MX2 in special function register ADCON are used for selection of the analog input
channel.
Port 6 is a dual purpose input port. lf the input voltage meets the specified logic levels, it can also
be used as digital inputs regardless of whether the pin levels are sampled by the A/D converter at
the same time.
Semiconductor Group
– 8 multiplexed input channels
– The possibility of using the analog inputs (port 6) also as digital inputs
– Programmable internal reference voltages (16 steps each) via resistor array
– 8-bit resolution within the selected reference voltage range
– Internal start-of-conversion trigger
– Interrupt request generation after each conversion
A/D Converter
6-57
On-Chip Peripheral Components
C515