C509-L_97 Datasheet, PDF (184/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C509-L
The bits MX0 to MX2 in special function register ADCON0 and the bits MX0 to MX3 in ADCON1 are
used for selection of the analog input channel. The bits MX0 to MX2 are represented in both
registers ADCON0 and ADCON1; however, these bits are present only once. lf all 15 multiplexed
input channels are required register ADCON1 has to be used for channel selection. lt contains the
four-bit field MX0-3 to select one of the 15 input channels, the eight inputs at port 7 and the seven
inputs at port 8. Thus, there are two methods of selecting a channel of port 7 and it does not matter
which is used: If a new channel is selected in ADCON1 the change is automatically done in the
corresponding bits MX0 to MX2 in ADCON0 and vice versa. lf bit MX3 is set, the additional analog
inputs at port 8 are used. MX0-2 then determine which channel of port 8 is being selected.
Ports P7 and P8 are dual purpose input ports. lf the input voltage meets the specified logic levels,
they can be also used as digital inputs regardless of whether the pin levels are sampled by the A/D
converter at the same time.
The special function register ADDATH and ADDATL hold the converted digital 10-bit data result.
The data remains in ADDAT until it is overwritten by the next converted data. ADDAT can be read
or written under software control. lf the A/D converter of the C509-L is not used, register ADDATH
can be used as an additional general purpose register.
Semiconductor Group
6-106
1997-10-01