Post by thread:SX Power On Reset problem

Hello everybody I'm having problems with getting a SX28AC chip to reset at power on. When the power in my circuit has been turned off for long enough (a couple of seconds) the SX won't reset on the next power on. Instead it sets or quickly pulses some of my port pins after abt 65 ms. If I now manualy reset it by bringing the *MCLR pin low and high again it allways resets as it should. I have also tried to hold *MCLR low for a couple of seconds when power is switched on and then returning it high. This won't reset the chip either, but the next toggle of the *MCLR pin will. I have tried using both the internal brownout detector and an external DS1233 reset chip with the same result. The risetime of the 5V to the chip is less than 10 ms at power up (and it looks clean). I am using the internal oscillator at 4MHz with the Turbo fuse enabled. Is there anybody else with similar POR problems with the SX chip? ============================== Ruben Jvnsson AB Liros Elektronik Box 9124, 200 39 Malmv, Sweden TEL INT +4640142078 FAX INT +4640947388 spam_OUTrubenTakeThisOuT2.sbbs.se ==============================

Forget about it, I found it myself. I was enabling the RTCC rollover interrupt a couple of instructions before I was initiating some registers for the interrupt routine. One of these registers was holding a jump offset to be used inside the interrupt routine. Apparently, because of the random value of RTCC at power on, a interrupt was generated before this register was initiated. Putting a clr RTCC before enabling the RTCC rollover interrupt solved the problem. And I was sure this was a hardware problem! {Quote hidden}> Hello everybody > > I'm having problems with getting a SX28AC chip to > reset at power on. > > When the power in my circuit has been turned off for > long enough (a couple of seconds) the SX won't reset > on the next power on. Instead it sets or quickly pulses > some of my port pins after abt 65 ms. If I now manualy > reset it by bringing the *MCLR pin low and high again > it allways resets as it should. I have also tried to > hold *MCLR low for a couple of seconds when power is > switched on and then returning it high. This won't reset > the chip either, but the next toggle of the *MCLR pin will. > > I have tried using both the internal brownout detector and > an external DS1233 reset chip with the same result. > > The risetime of the 5V to the chip is less than 10 ms at > power up (and it looks clean). > > I am using the internal oscillator at 4MHz with the Turbo > fuse enabled. > > Is there anybody else with similar POR problems with the > SX chip? > > ============================== Ruben Jvnsson AB Liros Elektronik Box 9124, 200 39 Malmv, Sweden TEL INT +4640142078 FAX INT +4640947388 .....rubenKILLspam@spam@2.sbbs.se ==============================