RTE-V821-PC
USER’ S MANUAL
9
3.9. CPU TEST PINS (JCPU)
The JCPU connector pins are connected to the corresponding CPU pins. The connector pin
numbers correspond to the CPU pin numbers on a one-to-one basis. The connector pins can
be used to handle CPU signals for circuit expansion or test purposes.
3.10. CLOCK SOCKET (OSC1)
The OSC1 socket is connected to an oscillator or crystal used to supply clock pulses to the CPU.
The V821 can use a PLL for system clock generation. The PLL mode is selected according to
the state of the TCLR/P00 pin at a reset. The TCLR/P00 pin is pulled down with 47 k
Ω
in the
RTE-V821-PC, so the PLL mode is usually selected. In this case, the frequency of the
oscillator or crystal connected to the OSC1 socket is one-fifth the system clock frequency.
When the TCLR/P00 pin is high, the frequency of the oscillator or crystal is twice the system
clock frequency.
The OSC1 socket accepts a 14-, 8-, or 3-pin oscillator, or a crystal. The oscillator and crystal
should be mounted as shown below. Capacitors must be used together with the crystal.
3-pin oscillator
8-pin oscillator
14-pin oscillator
1PIN
1PIN
1PIN
How to Mount Oscillators
Capacitor
Crystal
Capacitor
1PIN
How to Mount a Crystal
[Caution]
When a crystal is used, oscillation may become unstable and inoperable. It is
recommended that an oscillator be used.
