| ??? 08/09/05 10:59 Read: times |
#99029 - Power cycling not below 0.20V ? Responding to: ???'s previous message |
Hello Prahlad,
Thank you very much, I have always believed in Philips microcontrollers and your assurance encourages me to use them. Thanks for the schematic, I had seen this circuit earlier on the Keil website, but your circuit has made it clearer and I am going to implement it. Erik, Your bakdoor has helped me lot with other Philips micros, and the first thing I did was to implement your notouch with the LPC921, with the appropriate changes (adding the authorization key)but it is not working, obviously I am doing something wrong. Please read the following (from Philips erata): P89LPC932 Philips Semiconductors Low Pincount 8-bit microcontroller Erratasheet Errata Notes VDD.1: VDD Power cycling To generate a proper Power-On-Reset (POR), VDD must have dropped below 0.2V before being powered back up. Power-cycling without VDD having dropped below 0.2V may result in unintended In-Application Programming (IAP) calls which can cause modification of the Flash memory as well as the configuration and security bytes. Please also see the VPOR specification in LPC932 Datasheet Rev 03 and higher, DC electrical characteristics. Section 8.15 (Reset) states that during a power cycle, VDD must fall below VPOR. What about brownout (and other power cycling conditions where the Vdd does not drop below 0.20V), when the Vdd does not drop below 0.20V, will it cause inadvertent flash corruption? This above note from Philips is nagging me! Regards, John. |
