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Parallax Bs2P40 (SX48BD/TQ) Spontaneous Reboot
Hello Parallax forum,
I have seen a few instances where my BS2P40 OEM SMT IC has rebooted spontaneously. I have removed my external brownout circuitry connected to the RESET Pin 1 and applied a 10K pull up on this pin as per the guidelines activating the internal reset circuitry. I've still seen the CPU reset on occasion. In reviewing the data sheet of the SX48BD/TQ, there 4 reset possibilities:
1. Power-on reset
2. Watchdog reset
3. External reset
4. Brownout reset
I am not aware of how the watchdog reset is programmed so i don't believe this is involved. I have disconnected my external reset circuitry so i know this is no longer present. I do know that the DC power drops as i load the circuit board from 4.98 VDC to about 4.7 VDC. I do not have decoupling capacitors present (yet) on the 4 Vdd pins - (will plan to add those) in a future board spin. That being said, unless the undershoot of the Vdd voltage is triggering the internal brownout circuitry, i would have to rule out brownout as a reset condition. As well, this is not a power-on reset so i also rule this out as the CPU is running an active program when this occurs.
Does anyone have any other possible reasons or easy checks to see why the CPU is rebooting?
Thanks very much,