MC68307V Datasheet, PDF (13/34 Pages) Motorola, Inc – Technical Summary Integrated Multiple-Bus Processor

DUAL TIMER MODULE
The MC68307 includes two independent, identical, general-purpose timers. Each general-purpose timer block
contains a free-running 16-bit timer which can be used in various modes, to capture the timer value with an
external event, to trigger an external event or interrupt when the timer reaches a set value, or to count external
events. Each has an 8-bit prescaler to allow programmable clock input frequency derived from the system
clock (divided by 1 or by 16) or external count input. The output pins (one per timer) have a variety of program-
mable modes and the output signal can be an active-low pulse or a toggle of the current output. The features
of the 16-bit timer include:
• Maximum period of 16 seconds (at 16.67 MHz)
• 60-ns resolution (at 16.67 MHz)
• Programmable sources for the clock input, including external clock
• Input capture capability with programmable trigger edge on input pins
• Output compare with programmable mode for the output pins
• Two timers externally cascadeable to form a 32-bit timer
• Free-run and restart modes
Dual Timer Programming Model
Table 8 shows the programming model for the dual timer module. The FC (function code) column indicates
whether a register is restricted to supervisor access (S) or programmable to exist in either supervisor or user
space (S/U). The address column contains the offset from the base address (MBASE) contained in the SIM07
MBAR.
Table 8. Dual Timer Module Registers
Address
FC
Register Name
MBASE+$120 S/U
Timer mode register 1 (TMR1)
MBASE+$122 S/U
Timer reference register 1 (TTR1)
MBASE+$124 S/U
Timer capture register 1 (TCR1)
MBASE+$126 S/U
Timer counter 1 (TCN1)
MBASE+$129 S/U Do not access byte $128 Timer event register 1 (TER1)
MBASE+$130 S/U
Timer mode register 2 (TMR2)
MBASE+$132 S/U
Timer reference register 2 (TRR1)
MBASE+$134 S/U
Timer capture register 2 (TCR2)
MBASE+$136 S/U
Timer counter 2 (TCN2)
MBASE+$139 S/U Do not access byte $138 Timer event register 2 (TER2)
MOTOROLA
MC68307 TECHNICAL INFORMATION
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