Timer Input Select Header (J15) - Motorola M68705EVM User Manual

2.3.5 Timer Input Select Header (J15)
Jumper header J15 is used to select either a pulsed (PUL) or gated (GAT) mode of operation
for the MC6805R2 MCU, if installed in socket U21. The EVM is factory-configured and
shipped with the gated mode selected. This is accomplished by the installation of a
fabricated jumper on pins 2 and 3 as shown below.,
J15
1
•
PULSED MODE (PUL)
2
I
GATED MODE (GAT)
3
The EVM simulates both the gated and the pulsed modes of the MC6805R2 MCU. In the
gated mode, the internal phase 2 (02) clock is gated by the signal applied to the MCU timer
input. In the pulsed mode, the timer counts the input pulses applied to the MCU timer input.
When the pulsed mode is required, the fabricated jumper must be repositioned between pins
1 and 2.
The MC68705R3/U3 MCU timer is software programmable. Both the timer input and
prescaler selection capabilities (via jumper headers J15 and J20, respectively) are bypassed
when reconfiguration for either the MC68705R3/U3 MCUs are made via the MCU select
header J16. (Refer to paragraph 2.3.1.)
EVALUATION MODULE USER'S MANUAL
M68705EVM
MOTOROLA
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