Freescale Semiconductor Microcontrollers - Manual (Page 606)

ColdFire V1 Full Chip Simulation Connection
FCS Visualization Utilities
606 Microcontrollers Debugger Manual
Scanning is one method to read such keyboards. Typically, we can proceed as follows (the
line being in output and the column in input):
• Put a 0 at line X4 (X3, X2, X1, X0 being at 1).
• Read the column successively, from Y3 to Y0.
• Put a 0 at line X3 (X4, X2, X1, X0 being at 1).
• Read the column again from Y3 to Y0.
• Continue till the last column of the last line, and restart at the beginning
All keyboard keys are scanned until we find one that is activated. During the scanning
process, it is easy to update a counter representing the number of the key pressed. Raising
an interruption when a key is pressed allows you to scan only when a key is activated
rather than constantly.
IT_Keyboard Menu
Figure 28.28 shows the IT_Keyboard menu. Table 28.5 describes the menu entries.
Figure 28.28 IT_Keyboard menu
Table 28.5 IT_Keyboard Menu Description
Menu Entry Description
Setup Opens the Interrupt keyboard setup dialog.