SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 85

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

Table 7-6
Selection of the Analog Input Channels
MX3
0
0
0
0
0
0
0
0
1
1
1
1
*) X means that the value may be 1 or 0.
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. Table 7-6 lists the selected input channels. The bits
MX0 to MX2 are represented in both the registers ADCON0 and ADCON1; however, these bits are
present only once; it has the same effect irrespective of whether they are accessed via ADCON0
or ADCON1. This is done in order to maintain software compatibility to the SAB 80(C)515. In this
device there are only eight input channels which are selected by MX0 to MX2 in ADCON0. Thus, a
program written for the SAB 80(C)515 selects one of the lower eight input channels (port 7) if the
bit MX3 is reset which is the default value after reset. (For clarity: In the SAB 80(C)515 the analog
input channel is called port 6 or AN0 to AN7, resp. However, it is found on the same address (0DB H )
as the SAB 80C517’s port 7.)
lf all 12 multiplexed input channels are required register ADCON1 is to be used. lt contains a four-
bit field to select one of all 12 input channels, the eight inputs at port 7 and the four 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 and MX1 then determine which channel of port 8 is being selected (see table 7-6).
Semiconductor Group
MX2
0
0
0
0
1
1
1
1
X
X
X
X
*)
MX1
0
0
1
1
0
0
1
1
0
0
1
1
MX0
0
1
0
1
0
1
0
1
0
1
0
1
Selected Channel
Analog input 0
Analog input 1
Analog input 2
Analog input 3
Analog input 4
Analog input 5
Analog input 6
Analog input 7
Analog input 8
Analog input 9
Analog input 10
Analog input 11
86
On-Chip Peripheral Components
Pin
P7.0
P7.1
P7.2
P7.3
P7.4
P7.5
P7.6
P7.7
P8.0
P8.1
P8.2
P8.3