System information

Auxiliary Timer/Counter Channels
50 – Reference VSBC-6 Reference Manual
Auxiliary Timer/Counter Channels
The VSBC-6 includes three uncommitted 8254 type counter/timer channels for general
application program use. Control signals for the three channels are available on connector J6.
J
UMPER
C
ONFIGURATION
Jumper V2 selects the clock source for channels 4 and 5. Options include:
• Internal 6 MHz timebase
• External clock from connector J6
• Cascading channels 4 and 5 together for 32-bit counter/timer operations
See page 20 for jumper configuration details.
E
XTERNAL
C
ONNECTIONS
Table 27: Counter/Timer I/O Connector
J6
Pin
Signal
Name Function
1 OCTC3 CTC Channel 3 Output
2 GND Digital Ground
3 ICTC4 CTC Channel 4 Input
4 GND Digital Ground
5 OCTC4 CTC Channel 4 Output
6 GND Digital Ground
7 ICTC5 CTC Channel 5 Input
8 GND Digital Ground
9 OCTC5 CTC Channel 5 Output
10 GND Digital Ground
C
OUNTER
/ T
IMER
R
EGISTERS
Table 28: Counter / Timer Registers
Mnemonic R/W Address Name
T3CNT R/W 0044h Timer 3 Count Load/Read
T4CNT R/W 0045h Timer 4 Count Load/Read
T5CNT R/W 0046h Timer 5 Count Load/Read
TCW W 0047h Timer Control Word
O
PERATION
Operational details for this industry standard 8254 type counter/timer chip are beyond the scope
of this manual. Register details, operational modes, and programming information can be
obtained from the VersaLogic website by downloading the 8254.PDF data sheet.