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R-IN32M4-CL3 User's Manual: Board design edition
3.2
Notes on Configuring the Oscillation Circuit
As the R-IN32M4-CL3 includes an oscillation block, oscillation circuits are easily configurable by externally connecting
a resonator and components for external constants. Though configuring an oscillation circuit is easy, the configured
circuit is analog and operates at a high frequency, so notes that differ from the usual logic circuit configuration.
To achieve stable operation of the oscillation circuit, set components for external constants to the optimum values
(capacitors on the input and output sides, and limiting resistors) and observe the following points required for an analog
circuit.
Place the oscillation circuit near the R-IN32M4-CL3.
Place the oscillation circuit as far as possible from high-frequency input pins such as clock pins.
Place the resonators and components for external constants immediately close to the input and output pins of
oscillation circuit, and keep the connections as short as possible.
Make the ground connections of the capacitors to the GND pins of R-IN32M4-CL3 as short and thick as possible.
Make the lead wires between the resonator and capacitors as short as possible.
Surround the components for external constant parts by as much GND wiring as is possible.
Figure 3.1 Example of GND Pattern for the Components for External Constants
In addition, the following points to note should be observed in evaluating and determining the external constants.
The range of oscillating operation may vary due to the dielectric constant of the board's material, so use the actual
printed circuit board that will be used in the finished design.
Check use of the board with the developed R-IN32M4-CL3 and the actual resonator to be mounted on it.
R18UZ0074EJ0100
Dec 24, 2019
OSCTH
R-IN32M4-CL3
XT1
Board
GND pattern
XT2
3. Clock Input Pins
Page 8 of 61
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