I have NanoPi DUO2 powered from 12V battery with D24V6F5 regulator. Because the device will be mostly unattended I need solid watchdog solution.
So I have designed separate circuit base on small PIC 12F1571. PIC on pin RA2 receive “heart beat” signal from NanoPi and in case when hard reset is necessary send “0” on pin RA4 - connected to SHDN pin on D24V6F5. But nothing happens - D24V6F5 don’t react on changing voltage level on pin SHDN from 5V to 0V.
To be sure that shutdown signal is delivered I have soldered led with 1k resistor between GND and SHDN to see what happens because touching SHDN pin with multimeter reset D24V6F5 module.
Please look at schematic attached.
What I’m doing wrong ? I have tested this on two D24V6F5 modules.