Pins and ports

The F690 version that we describe here has a 20-pin double-in-line package (opposite). Other packages are obtainable, such as surface-mount devices, for example.

All pins except 1 and 20 are available for use as input/output pins. Those of Ports A and B can be individually set to have built-in pull-ups when configured as inputs. Also, as inputs, they can be programmed to cause interrupts when the input signal changes.

Certain of the pins, though usable for simple input or output, can be programmed to have special functions. For example, pin 4, RA3, can be programmed to act as a master clear input which, when made low, resets the PIC to the start of its program.

Another example is pin 10, RB7. If you are using the USART (pp. 124-126), this pin must be used for data that is being sent to another PIC by line or radio. There is more about these special pin functions later in this Part.

0

19

RAO

+v

RB4

1

18

RAI

ïï RB5

2

17

Q_

4

RA3 >

RB7

3

3

RA4

2

RA5

RCO RC1 RC2

PIC16F690

^ RC3 o RC4

RC5

RC6

0 V

16 15

Ports and pin numbers of the PICI6F690 controller. The channels of each port are numbered from 0 to 7, from the least significant to the most significant bit. Port A has only six channels. Port B has channels for only the four most significant bits.

The figures on grey are the digital input channels AN0 to AN11. For AN0 to AN7 these figures are also the bit numbers in the ANSEL register. For AN8 to AN 11, the bit numbers in the ANSELH register are given in brackets,

The channels marked with an asterix are also availlable for input to the comparators.

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