Recommendation for Hardware Setup 32-Bit FR81S Family
Document No. 002-09375 Rev. *B
4
2.6
Reset Pin (RSTX)
To reset the MCU a switch connects this pin to Vss (Ground). There is internal 50k pull-up resistor, but for high noise
requirements an external pull-up resistor with typical 10k is recommended. Additionally, a capacitor has to be connected
between Vss and the reset pin for debouncing the switch and for EMI protection. From experience a capacity of not
more than 1 nF is recommended. This capacity covers the most common frequency protection in a wide range. Higher
capacities and high impedance may cause latch-up effects together with an RSTX-Switch and low EMI protection. The
reset level of RSTX pins depends on the logical level on NMIX pin. Please refer to Hardware manual chapter 7 Reset.
Table 2. RSTX and NMIX Function
RSTX
NMIX
Function
1
1
Normal operation
1
0
Non maskable interrupt
0
1
External reset
Reset (RST)
Synchronous reset factor
0
0
Irregular reset
Initialize reset (INIT)
Asynchronous reset factor
(not guarantee that memory contents have not been destroyed by the reset)
2.7
Non maskable Interrupt Pin (NMIX)
The NMIX supports two several functions, (a) using as NMI input and (b) simultaneous assert of RSTX and NMIX pins
to generate an irregular reset. There is internal 50k pull-up resistor, but for high noise requirements an external pull-up
resistor with typical 10k is recommended.
