mc68hc05pv8a Freescale Semiconductor, Inc, mc68hc05pv8a Datasheet - Page 105

• Manufacturer Part Number: mc68hc05pv8a
• Description: Mc68hc05pv8a Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Freescale Semiconductor, Inc.
Input/Output Ports
Port C (High Voltage Port)
CSDT
Interrupt
PC4
DDR
DATA
VSS
Figure 7-11 PC4 Circuitry 68HC05PV8A
Port pin PC0 comprises a circuit that senses the outside resistance R
PIN
to VSUP. PC4 has a different circuit, which senses the outside
resistance R
to VSS (only on 68HC(8)05PV8). PC1, PC2 and PC3
PIN
have an universal one, which senses the outside resistance either to
VSS or to VSUP, depending on the state of the corresponding data
register bit.
The contact sense circuitry is enabled by setting the corresponding bits
PC4CS, PC3CS, PC2CS, PC1CS or PC0CS of the port C configuration
register to 1. In addition, the pin has to be configured as an output by
setting the corresponding DDR bit to 1 and the data bit to 0 (for R
to
PIN
VSUP, e.g. external switch to VSUP) or to 1 (for R
to VSS, e.g.
PIN
external switch to VSS). If the outside resistance R
is lower than the
PIN
specified value, the contact sense circuitry interprets this as a logical 1.
The principal sense characteristic is given in
Figure
7-12. The result of
this sense operation is given by the bits CSD4, CSD3, CSD2, CSD1 and
CSD0 of the port C status register.
MC68HC(8)05PV8/A — Rev. 1.9
Technical Data
Input/Output Ports
For More Information On This Product,
Go to: www.freescale.com