B&B Electronics PPIO Benutzerhandbuch

10 

PPIO2899 Manual 

Table 2 

 

 

 

The big advantage of using the ANDing and ORing as shown in 

Table 2 is that it makes each PPIO pin independent. If you have, for 
instance, PPIO bit 2 ON and all of the rest of the bits OFF then your 
variable OB will be equal to 04H (00000100 binary). PPIO bit 2 will 
be LOW or ON. If you then want to turn ON bit 3 do the following: 
 
500 OB=OB OR &H08 
520 OUT &H378,OB 
 
Bit 3 will go LOW and bit 2 will stay LOW. At that time OB will be 
equal to &H0C (00001100 binary). To turn OFF bit 3 do the 
following: 
 
700 OB=OB AND NOT &H08 
720 OUT &H378,OB 
 
Bit 3 will go HIGH or open and bit 2 will stay LOW. By using the OR 
and AND NOT commands in Table 2, bit 3 has been turned ON and 
OFF without disturbing any of the other PPIO Bits. 
 

 

 

You may also use the PPIO with some pins as inputs and some 

pins as outputs. There can be any number of each and in any order. 
Remember that before you can use a PPIO pin as an input you must 
first force the output driver on that pin OFF by putting a ZERO on 
that bit. For example suppose we want to use bits 0, 1, and 2 as 
outputs and bits 3, 4, 5, 6, and 7 as inputs. We also want bit 1 to be 
ON (or LOW) when we start the program. We need to turn OFF bits 
3, 4, 5, 6, and 7 so we can use them as inputs and turn ON the 
output bit 1. You should modify Figure 2 to add the following line: 
 
180 OUT &H378,&H02 
 
 

From then on you can use the first three lines of Table 2 to 

control the three outputs and lines 220-320 of Figure 2 to input data. 

0 

OR &H01 

AND NOT &H01 

1 

OR &H02 

AND NOT &H02 

2 

OR &H04 

AND NOT &H04 

3 

OR &H08 

AND NOT &H08 

4 

OR &H10 

AND NOT &H10 

5 

OR &H20 

AND NOT &H20 

6 

OR &H40 

AND NOT &H40 

7 

OR &H80 

AND NOT &H80