USB Tester OLED Backpack with Display Fundraiser

Today we have started the fundraiser for the USB Tester OLED backpack with the display. This is a great addition to the USB Tester, which makes it easy to monitor voltage and current for any USB device. Now you don't even need your DMM. You can use this to see how much power your Raspberry Pi is using or that custom Arduino based project you are working on. This is a great way to make sure you aren't getting a voltage drop due to that USB hub you are using. Check out the product description below and thanks for your support. You can back your here: https://www.tindie.com/shops/FriedCircuits/usb-tester-oled-backpack-with-display/

USB Tester OLED Backpack measuring Raspberry Pi

USB Tester OLED Backpack: Surprise Feature 3 (Not Needed Anymore)

This post was about a feature I was going to add, but after prototyping I realized that it isn't needed. The microcontroller can be connected to both power sources and before the sense resistor without any affect on measurements. The maximum power you can use is still affected as mentioned at the end of the post.

If no host computer is connected for the microcontroller, it will draw power from the same source as the device you are measuring. This can make it convenient for checking a device without needing to be near a computer or 2nd power source. This will be great for testing on the spot. In the future it might be possible to do some light data logging to the microcontroller via a firmware update or if someone wants to add it. It would be possible to design another addon to add a SD card or flash memory for logging.

I thinking that instead of the switch I could have a solder jumper so that you can still discount the power from the measuring device and or add a button for future use.

Post your thoughts below of what you would like to see.

Here is the original post:
In December we released the USB Tester for measuring voltage and current of your USB project and devices. This tool made it easier to connect your digital multi-meter for measurement. You can read the full product description here: http://www.mobilewill.us/2012/12/our-first-product-usb-tester.html. This month we are working on releasing an OLED Adapter backpack. This will allow you to view the voltage and current without the need for a DMM.

Previously I announced two features:

http://www.mobilewill.us/2013/01/usb-tester-oled-backpack-surprise.html

http://www.mobilewill.us/2013/01/usb-tester-oled-backpack-surprise_28.html

Today I wanted to announce the final feature that the OLED Backpack will have.

The final feature will be a power source selector switch. This allows you to power the OLED display and microcontroller from the same source as the project you are measuring. This will be great when you are measuring a device away from a computer such as a phone charging, Raspberry Pi, or something that is greater than 500mA. Once you are back at a computer and want to data log, you can flip the switch to the off position. The switch is also connected to a pin on the microcontroller so it would know the power source.

Remember that it will slightly reduce the maximum power your measuring device can use depending on your power source. For example, if you are measuring an XBee from a 500mA power supply with the switch on, the maximum the XBee could use is 460mA, since the backpack with the OLED display is about 40mA. So for the most part it shouldn't be enough to affect most devices.

This will be a great feature for measuring devices on the go. I can't wait to finish development and get this in your hands to help your project developments!

Thanks for the support. Look for the upcoming fundraiser on www.tindie.com.

WiFi Thermostat Control Part 1

Living in an Apartment can be a challenge when it comes to home automation. Most projects require modifying or tapping into the building in one way or another. Our Apartment was remodeled before we moved in but they didn't replace the aging thermostat. It is the old style with the lever on top that controls a glass tube of mercury. I knew I could replace the thermostat with some relays and a microcontroller or get a retail WiFi thermostat but I needed something that didn't modify it in any away.

Sparkfun XBee Shield Fix

There is a known problem with the older Sparkfun Xbee Shield with Xbee Series 2 and the Wifly radio. It has to do with the level shifting on the DIN pin. They use a diode to drop the voltage which works for the regular Xbee Series 1 radios which have a built in pullup to VCC. The series 2 is not enabled by default and the Wifly's don't have the option at all. Here is a quick fix that will get you up and running in no time.

As you can see in the picture I added a 10k pullup resistor between VCC which is 3.3V and DIN. Originally I was going to use a though hole part but realized it would be easier with a SMD resistor I had. You can use either. The resistor can go either direction and has to be between DIN on the radio and the diode. I found the easiest way was to use the header pins that are attached directly to the radio. I used a small wire that I had clipped off a through hole resistor to get the other side of the resistor connected.

I hope that helps anyone struggling with getting this shield to work with other radios. This only applies if you have the older version. I realized that Sparkfun has a new version that does proper level shifting. I have two of these that needed the fix but on the second one I am using it at 3.3V, so I just bypassed the diode completely.

USB Tester Review by Hybernaut's Tinker Blog

An awesome review of the USB Tester can be found over at

Hybernaut’s Tinker Blog

http://tinker.hybernaut.com/blog/2013/02/03/friedcircuits-usb-breakout. Thanks goes to Daniel, the software engineer behind the blog, for mentioning and linking up the USB Tester and the USB Tester OLED.

Be sure to check out his site - it's a new one to watch!