| ??? 10/03/07 18:28 Modified: 10/03/07 18:30 Read: times |
#145306 - bidir reset, if there is an internal supervisor Responding to: ???'s previous message |
Erik Malund said:
never heard of a "bidirectional reset" give a link, please An internal supervisor (this includes any form of watchdog) without an output, ergo such which resets themicro without "letting it know" to the attached peripherals, is in my opinion heavily flawed (ergo, most of the "modern" '51 derivatives are crippled in this respect). In the '51 world, one good example is DS89C4x0: DS89C450 datasheet said:
External Reset. The RST input pin is bidirectional and contains a Schmitt Trigger to recognize external active-high reset inputs. The pin also employs an internal pulldown resistor to allow for a combination of wire-ORed external reset sources. An RC is not required for power-up, as the device provides this function internally. The last line has to be taken conditionally, see note 3 on page 3 (which basically says that the internal supervisor's trip voltage is below VCCmin and an external supervisor is a must). In this case, a serial resistor of an appropriate value has to be placed between the external supervisor and the bidirectional RESET, or other adequate solution has to be developed to avoid conflict. JW PS (later) now I see you said the same in the subsequent post |
