RESET pin strength (m48/88)

Log in or register to post comments
Go To Last Post
2 posts / 0 new
Author
Message
Brutte
Brutte's picture
Level: Raving Lunatic
Joined: Thu. Oct 5, 2006
Posts: 3229 View posts
Location: Poland
#1
Posted by Brutte: Wed. Jun 8, 2011 - 09:47 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Using AVRs and RESET pin is more complicated than other IOs. I just want you to confirm if I am right about this pin functionality as an IO.

RESET pin on AVRs with RSTDISBL fuse can be (part dependent):

    1) Open drain IO driver (mature tn12) 2) Weak IO driver (tn2313,tn13..)
    3) Regular strength IO driver?

QA: Datasheets of m48/88/168, usb82/162 and other AVRs with RESETDSBL fuse do not mention the difference in between RESET and a regular IO driver strength in "Pin Driver Strength" sections because:

    a) there isn't any difference. b) Atmel forgot to write about this fact, and it is still 2) type weak IO capable of 1mA sink/source?

QB: Is this pin still 12V capable, when RSTDISBL is programmed? What happens when it is on 12VDC and I set IO high?

No RSTDISBL, no fun!

Tags:

AVR Microcontrollers, megaAVR and tinyAVR
Top
Gold Markclawson
clawson's picture
Level: Moderator
Joined: Mon. Jul 18, 2005
Posts: 104792 View posts
Location: (using avr-gcc in) Finchingfield, Essex, England
Posted by clawson: Thu. Jun 9, 2011 - 09:00 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

QB: Once RSTDISBL is set then the only way to program the chip *is* using HV programming which involves applying +12V to the _RESET pin. As this immediately triggers the core into a "ready to be programmed" mode the CPU is not making instruction fetches and whatever software you may have in the flash is completely irrelevant as the CPU will not be running in the "normal" sense.

Top