Shield ID chip

Home Forums Hardware AutoSense Shield Shield ID chip

This topic contains 0 replies, has 1 voice, and was last updated by Profile photo of Eric Eric 1 year, 9 months ago.

Viewing 1 post (of 1 total)
  • Author
    Posts
  • #1869
    Profile photo of Eric
    Eric
    Keymaster

    So in order for the shield to have some of the capabilities I wanted, things like the ability to identify what features it has, as well as control the power for the Due I need a small micro processor, and since I have a bunch of ATTiny85 chips and I’m familiar with them they should work nice. Now of course for it to be useful it needs to be running all the time and have the ability to sense whether the car is on or not so I’ve hooked it up to a opto isolator to sense the presence of 12 volts or not for the accessory line. This is working very well, but since it’s going to be running all the time I want to reduce power consumption as much as possible. So I’m running at 3.3 volt, and I’ve slowed the core speed down to 1 MHz which has dropped the power consumption to a little over 1 milliamp, pretty good for something that will always be running. A typical LED draws about 20 milliamps. But I can do better 😉 Playing with the sleep modes, putting the chip into power down mode and only waking when the accessory line is high, brings the current draw down to 20 microamps. That’s a 1000% reduction in current draw. If your car battery dies it won’t be from this little guy 😀

  • Author
    Posts
  • #1869
    Profile photo of Eric
    Eric
    Keymaster
    • Offline

    So in order for the shield to have some of the capabilities I wanted, things like the ability to identify what features it has, as well as control the power for the Due I need a small micro processor, and since I have a bunch of ATTiny85 chips and I’m familiar with them they should work nice. Now of course for it to be useful it needs to be running all the time and have the ability to sense whether the car is on or not so I’ve hooked it up to a opto isolator to sense the presence of 12 volts or not for the accessory line. This is working very well, but since it’s going to be running all the time I want to reduce power consumption as much as possible. So I’m running at 3.3 volt, and I’ve slowed the core speed down to 1 MHz which has dropped the power consumption to a little over 1 milliamp, pretty good for something that will always be running. A typical LED draws about 20 milliamps. But I can do better 😉 Playing with the sleep modes, putting the chip into power down mode and only waking when the accessory line is high, brings the current draw down to 20 microamps. That’s a 1000% reduction in current draw. If your car battery dies it won’t be from this little guy 😀

Viewing 1 post (of 1 total)

You must be logged in to reply to this topic.