Pages: [1]   Go Down
Author Topic: Reset pin on ATtiny84  (Read 558 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Full Member
***
Karma: 0
Posts: 139
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi,
  This is my first time using an ATtiny84 and I just wanted to verify two things.
First in the attached picture is this the correct setup for the reset pin with a pushbutton? The resistor value is 10K Ohm
Secondly does anyone have a suggestion for a resistor value between on the pins and a PNP 2N3906 transistor?
Thanks in advance for your help.


* Screen Shot 2013-01-28 at 7.40.36 PM.png (10.47 KB, 339x179 - viewed 28 times.)
Logged

Grand Blanc, MI, USA
Offline Offline
Faraday Member
**
Karma: 92
Posts: 3940
CODE is a mass noun and should not be used in the plural or with an indefinite article.
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

(A) Yes, and
(2) I'd use 1000Ω, but it's probably not terribly critical.

 smiley
Logged

MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Offline Offline
Full Member
***
Karma: 0
Posts: 139
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks.
For the resistor is there an equation that you are supposed to use or is it just a rough value works?
Logged

Grand Blanc, MI, USA
Offline Offline
Faraday Member
**
Karma: 92
Posts: 3940
CODE is a mass noun and should not be used in the plural or with an indefinite article.
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks.
For the resistor is there an equation that you are supposed to use or is it just a rough value works?

I just go with the latter.  Don't want to load the µC pin too much, but still want to drive the transistor to saturation. I'm sure an afternoon could be spent calculating the exact proper value, but 1K has worked well enough for me.

But just to be a little more thorough, what kind of transistor, and what will it be driving?
Logged

MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Offline Offline
Full Member
***
Karma: 0
Posts: 139
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

A PNP 2N3906 https://www.sparkfun.com/products/522 . It will be connected to a bunch of LEDs to turn them on and off.


* Screen Shot 2013-01-28 at 8.47.24 PM.png (8.72 KB, 155x291 - viewed 15 times.)
Logged

Grand Blanc, MI, USA
Offline Offline
Faraday Member
**
Karma: 92
Posts: 3940
CODE is a mass noun and should not be used in the plural or with an indefinite article.
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

That's probably a 100mA load, give or take. I'd try the 1K with one LED, measure the collector voltage, add a couple LEDs at a time. If the collector voltage doesn't get low enough to drive the LEDs bright enough, try one of those 330Ω guys on the transistor base instead. If that still doesn't achieve the desired results, then a different transistor might be in order.
Logged

MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Offline Offline
Full Member
***
Karma: 0
Posts: 139
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

The leds should not draw more than 160ma (8*20ma) so hopefully it will work. The description said up to 200ma. Do you think that there might be a problem, though?
Logged

Grand Blanc, MI, USA
Offline Offline
Faraday Member
**
Karma: 92
Posts: 3940
CODE is a mass noun and should not be used in the plural or with an indefinite article.
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Nah, go for it!
Logged

MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Offline Offline
Full Member
***
Karma: 0
Posts: 139
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for your help!!
Logged

Grand Blanc, MI, USA
Offline Offline
Faraday Member
**
Karma: 92
Posts: 3940
CODE is a mass noun and should not be used in the plural or with an indefinite article.
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for your help!!

Let us know if it was good help or ... otherwise smiley-lol
Logged

MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Pages: [1]   Go Up
Jump to: