ECE 4510/5530 MICROCONTROLLER APPLICATIONS
Fall 2008
Prelab Assignment for Lab Four
Port A (PA7…PA0) is designated as output port and Port B (PB7…PB0) as input
port for this lab (a carry over from Lab Three).
Task One
Part i
Your signal input is PA3, and signal output is PB5. Disconnect the DIP-switch
from the input of the buffer chip driving PB5 and hook it up to a TTL-compatible
signal originated from a function generator, instead. Draw a detailed schematic
diagram for Task One. It should include IC part numbers, IC pin numbers and H2
Connector pin numbers, respectively. All signal lines should be labeled. Before you
hook up the function generator output to the input of the buffer chip you should
verify by an oscilloscope that the square wave signal levels are between approx.
0 – 4V. You shouldn’t apply negative voltages, neither voltage levels greater
than 4.8V to the buffer chip! You should also verify that the VOH (output high
voltage) signal level at the output of the buffer chip is at least 4V before your
circuit is connected to the microcomputer board.
Develop a C code module for Part i.
Task Two
Part i
Disconnect the buffer output for the function generator signal from PB5 and hook it
up to IRQ* (PE1), instead. Draw a detailed schematic diagram for Task Two. It
should include IC part numbers, IC pin numbers and H2 Connector pin numbers,
respectively. All signal lines should be labeled.
Develop C code modules for the main program, and the ISR, respectively. The IRQ*
input should be configured to respond to falling edges only. You are to identify the
RAM-based vector location for IRQ* interrupts (refer to the D-BUG12 V.xx
Reference Guide that is posted under the 9S12DP512 Data Sheets Section of the
Class Web Page). For interrupt testing purposes, in the body of the ISR your code
should complement a bit and write it to PM7. If the interrupt works you should be
able to verify it visually, or by a logic analyzer that the PM7 output signal toggles
every time an interrupt request is received.
