Recently, hackaday.com posted some information on a new $5 wifi module out of china known as the ESP8266.
$5 wifi modules - hackaday.com
They’re being picked up and experimented with in various hackerspaces and I haven’t seen them mentioned here yet. I recently received mine and I’ve been doing some experimentation.
If anybody is interested, I could do a demonstration on what functions they have and how to get them working.
I am interested is connectivity (of the IoT kind) which this should fit well. So yes, I am interested in a demo/discussion/whatever. My thoughts are in the direction of simple sensors that collect and report back to the house server. Low power, simple tasks.
cheers
I’m interested as well.
Have you had a chance to do any analysis on power consumption? Where I see strong applications for this sort of device is distributed sensors/control around the house, which will generally be battery powered. There’s already some very good devices on the market in this segment, only around 3-4x the price of the ESP2866.
Not sure about the power consumption as I don’t have the equipment to check the power consumption myself.
I’m pretty sure that they’d use too-much to be driven by batteries continuously.
I have some small calculator/keyring-destined solar cells that create 3V at very low current.
One trick to achieving the desired outcome might be to charge a supercap/cap over time and turn the system on every hour or two for five seconds and then off the power till the next wakeup.
Not sure. I think the only way to solve these problems is by experimentation.
You’re quite right that powering up, sending the data, then going back to sleep is how it’s normally done to extend battery life (by a huge margin.)
These sort of applications typically measure power consumption in two parts, standby current (i.e. the power required while it’s asleep and running an RTC to wakeup or the like), and mA/h required to perform a specific action. For example a EFM Gecko uC needs 0.4uA in shutoff with the RTC running, then you might need 30mA for 100ms each update, or 8.3x10-5mA/h. From that it becomes pretty straightforward to calculate the expected battery life for a given update rate.
It’s fairly straightforward to measure these quantities just using an electro cap, power supply, DMM that has some sort of PC connection and a few lines of script. Happy to go through it sometime if you’re interested.
There’s now an API that’s just been published for this:
http://bbs.espressif.com/viewtopic.php?f=5&t=3&sid=9260cd0b0d2f5b724e0be79c86e8e758