OK, some bizarre problem: I'm trying to quick fix some
customer's problem of sometimes the 3.3V for LPC213x
might dip below 2.6V. Triggering a full chip reset
- Chip running and 3.3V might dip below 2.6V
- I cannot put a big Cap or SuperCap.
- When startup, the power is always stable at 3.3V,
There is some power surge/drop to <2.6V when some
devices are turn on later.
- There is no Flash Eprom updating/writing
- BOD is not being used, but it causes the reset
- It works fine on a LPC2124 as long as 1.8V is stable.
- Though PCB footprint designed for Both LPC2124 and
LPC213x, but I cannot use LPC2124 due to LPC2124's
This is the definition for PDBOD on PCON register,
from user manual:
remains operative during Power-down mode, such that
its Reset can release the microcontroller from Power-down
mode. When PD and this bit are both 1, the BOD
circuit is disabled during Power-down mode to conserve
power. When PD is 0, the state of this bit has no effect.>>
Tested on a LPC213x chip and It seems like that control
bit follows the spec "very closely". => Is there any other
way to disable the BOD??
How nice if future philips/nxp chips has following
dedicated eprom/flash "hard-configuration" bits:
- Programmable eeprom bit for Watch-Dog to
auto-run after reset
- Programmable eeprom bit BOD level/disable
- Programmable eeprom bit Code Read Security
- Programmable eeprom bit JTAG disabling