| ??? 04/22/07 14:01 Modified: 04/22/07 14:29 Read: times |
#137761 - RC-based reset? |
I'm using an AT89LV55 in a battery-powered project for school. After the thing sits idle for around 15 seconds, it puts the microcontroller (and several other onboard devices) into low-power or "sleep" modes to preserve battery life.
According to the datasheet for the AT89LV55, it can only be brought out of a powered-down state with an external reset. I have a normally-open SPST pushbutton switch I'd like to use to both wake the microcontroller from the powered-down state and to use as a user input device when the microcontroller is active. I'm having some problems figuring out a simple way to do this. Would the following work, if I were to set P3.2 and P3.3 to 0 before putting the project into the powered-down state? After the reset, I'd let both pins go HIGH by default. I'm working from a 3.3V power supply.
R1
P3.3<>-/\/\/-------------------------------------
10 kOhm |
Vcc |
|E |
|/ |
-----|B 2N3906 (PNP) |
| |\ |
| |C |
| / |
| \R3 510 Ohm N.O. SPST |
| / SWITCH |
R2 | | __|__ |
P3.2<>-/\/\/--O O--------------O O-----O
270 kOhm | | |
| / |
| \R4 510 Ohm |
| / |
| |C --- C
| |/ --- 1 uF
-----|B 2N3904 (NPN) |
|\ |
|E |
Gnd |
|
Reset<|------------------------------------------
Is there a simpler or better way to do it using generic components? I'd test it myself, but I can't get back to the lab for another few days. Thanks in advance! |
| Topic | Author | Date |
| RC-based reset? | 01/01/70 00:00 | |
| ??? | 01/01/70 00:00 | |
| Leakage ? | 01/01/70 00:00 | |
| My totem pole? | 01/01/70 00:00 | |
| what do you want to spend $1 on | 01/01/70 00:00 | |
| Are you sure this applies to his entire problem? | 01/01/70 00:00 | |
to generate a switch interrupt | 01/01/70 00:00 |