mc68hc05jb4p Freescale Semiconductor, Inc, mc68hc05jb4p Datasheet - Page 47

• Manufacturer Part Number: mc68hc05jb4p
• Description: Mc68hc705jb4 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

7.1
MC68HC05JB4
REV 2
In normal operating mode there are 19 usable bidirectional I/O lines arranged as
one 8-bit I/O port (Port-A), one 5-bit I/O port (Port-B), and one 6-bit I/O port
(Port C). The individual bits in these ports are programmable as either inputs or
outputs under software control by the data direction registers (DDRs).
Each pin on Port-A and Port-B has individual internal pull-up resistor (50k
cal) which can be enabled by software. In addition, port pins PA6, PA7, and all
port-B pins have built in Slow Falling Edge transition feature. This software select-
able feature helps to eliminate EMI noise.
Other functions such as high current drive, interrupt, are available on some port
pins via mask option.
SLOW FALLING-EDGE OUTPUT DRIVER
When enabled, the slow falling-edge output drive feature has a slow falling edge
(drops from 5.0V to 2.2V in 167ns typically, with 50pF load) followed by a fast tran-
sition to Vss. The fast transition duration is depending on the strength of the output
driver defined for each port.
Output Driver
50pF
Figure 7-1. Slow Falling-edge Output Driver
Freescale Semiconductor, Inc.
5.0V
2.2V
0V
For More Information On This Product,
INPUT/OUTPUT PORTS
Go to: www.freescale.com
INPUT/OUTPUT PORTS
February 24, 1999
SECTION 7
165ns
GENERAL RELEASE SPECIFICATION
330ns
typi-