Member Since: October 5, 2009

Country: United States



Electrical Engineer/Enthusiast

Programming Languages



CMU, Oakland University


Microcontrollers / Sensors



  • I’m not so sure this is true. Stepper motors may have a constant current when it is holding a position (because the load is purely resistive during that time). When a there is some dynamic loading on the motor , there will be some transient change in current draw that should be seen in the phase windings. Not to mention, when the motor is actively being stepped, there will be transient currents during the active switching of the phase coils.

    A way to monitor the DC current used by a stepper motor, would be to measure before the switches (ie. monitor the current supply to the h-bridge V+ supply, assuming an h-bridge is used).

  • Was interested until I saw the price :0(

  • You could also run android on a virtual machine on any computer you own with wifi and install the app, if the app really is the only or best way to configure the device.

  • This idea should win :0)

    Aside from dogs delivering pizzas, I’d like to see how this could benefit those who use seeing eye dogs…

  • Of course this is quicker, thus the article. However, the point to be made is that the actual programmed flash is not being verified at any level of the bootloader. Any failed-write (which is absolutely possible) will go unnoticed, because it is not being “Verified” by the verification option. Don’t get me wrong, they put that check-box in there for a reason right? (don’t want to verify your upload? Live on the edge and uncheck the box :0p

    I think the bigger picture here is what kind of embedded programmers to promote; those who get in the habit of cutting corners to save literally only seconds per upload, or those who can understand and appreciate the pitfalls of memory failures and robust verification processes to combat them.

  • After checking ‘STK500boot.c’ - There are no CRCs performed…I did notice an xor checksum routine which the bootloader does perform on received packets. Keep in mind, XOR checksums are not very robust and they are NOT CRCs (CRCs are much more robust, but they are not perfect).

    The Optiboot bootloader doesn’t seem to perform any checksums/crcs at all…

    Maybe not verifying correct flash upload is not such a great idea (on paper)?

  • I think this is a great post (comments included), not in the fact that people will begin to bypass the flash verification; but this should motivate those involved into learning how the bootloader works. By the way, you should be able to browse the bootloader source code to figure it out.

    Quoting the article: “It’s still unlikely an error will slip through the CRCs…”

    Try to figure out if the bootloader actually performs Cyclic Redundancy Checks (CRCs) on the written flash vs. data to be written to flash. I don’t know, but I don’t think it would perform it on the written flash…but let’s just find out for ourselves?

  • Sparkfun internship program: “ABCs and PCBs”

  • Another product sparkfun could sell: Panavise (not Jr.). It’s nice to have a vise with enough weight that it does not need to suction-cup to a desk (especially for me when I have to solder around things it cannot suction too).

  • I’d like to see more with Xilinx Zynq (FPGA + dual-core ARM on one chip). Search: Zybo