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Appendix C
To improve noise immunity, take measures against noise as follows:
Noise Measures for V
When noise falling below the rated voltage is input, an IC malfunction may occur. If desired
operations cannot be achieved, take measures against noise on the circuit board, such as designing
close patterns for circuit board power supply circuits, adding noise-filtering decoupling capacitors,
and adding surge/noise prevention components on the power supply line.
For the recommended patterns on the circuit board, see "Mounting Precautions" in Appendix.
Noise Measures for #RESET Pin
If noise is input to the #RESET pin, the IC may be reset. Therefore, the circuit board must be designed
properly taking noise measures into consideration.
For the recommended patterns on the circuit board, see "Mounting Precautions" in Appendix.
Noise Measures for Oscillator Pins
The oscillator input pins must pass a signal of small amplitude, so they are hypersensitive to noise.
Therefore, the circuit board must be designed properly taking noise measures into consideration.
For the recommended patterns on the circuit board, see "Mounting Precautions" in Appendix.
Noise Measures for Interrupt Input Pins
This product is able to generate a port input interrupt when the input signal changes. The interrupt
is generated when an input signal edge is detected, therefore, an interrupt may occur if the signal
changes due to extraneous noise. To prevent occurrence of unexpected interrupts due to
extraneous noise, enable the chattering filter circuit when using the port input interrupt.
For details of the port input interrupt and chattering filter circuit, see the "I/O Ports" chapter.
Noise Measures for UART Pins
This product includes a UART for asynchronous communications. The UART starts receive operation
when it detects a low level input from the SINn pin. Therefore, a receive operation may be started if the
SINn pin is set to low due to extraneous noise. In this case, a receive error will occur or invalid data will
be received.
To prevent the UART from malfunction caused by extraneous noise, take the following measures:
•
Stop the UART operations while asynchronous communication is not performed.
•
Execute the resending process via software after executing the receive error handler with a parity
check.
For details of the pin functions and the function switch control, see the "I/O Ports" chapter. For the UART
control and details of receive errors, see the "UART" chapter.
26-6
Measures Against Noise
and V
Power Supply Pins
DD
SS
Seiko Epson Corporation
S1C31D50 TECHNICAL MANUAL
(Rev. 1.00)
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