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ChrisZ

Member since Feb 2014 • Last active Jun 2018
  • 2 conversations
  • 12 comments

Hello, I am Christopher Ziolkowski, a EE with roughly 35 years of experience. I have done a fair amount of embedded programming, most of this related to analog sensor and instrumentation issues. I have worked in multiple assembly languages as well as C/C++. My first encounter with an embedded language was FORTH on 8 bit Motorola processors during the 1980's. FORTH was very liberating in that it took care of a lot of basic chores with regards to serial com, formatting and the like while allowing one to inline assembler for the truly time critical tasks. More recently I have tried eLua on both STM and TI parts; this included setting up my own build environment. For me the huge appeal of JavaScript is the ecosystem: Espruino, node, DroidScript, etc. that enable one language to be used at multiple scales.

Most recent activity

    • 2 comments
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  • in JavaScript
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    Hi all;
    The FFT display example on the Pixel intrigued me. Is the FFT implemented in JavaScript? Do the NRF parts have a hardware FPU?
    Thanks,
    ChrisZ

  • in General
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    Gordon
    I am just tinkering with "Yun Shield" and a Nucleo board I have lying about. The Yun shield is half the price of the official Yun ($30 vs $60US) and does not tie you to a 328 class chip for your analog IO. The Yun Shield does require a serial port mapped to the official Arduino TX/RX pins to work. For now I took of the links bonding the Nucleo serial port to the STLink USB adapter and installed the ones connecting it to the Arduino header. You can always use fly-wires on the pins to reconnect to the STLink.

    Starting with a clean sheet of paper one could pair the Pico with a LinkIt Smart: http://www.seeedstudio.com/depot/LinkIt-­Smart-7688-p-2573.html. The LinkIt is $15US and has double the RAM/Flash that the Yun does on the OpenWRT side. That combo of Pico analog IO and an Espruino package that runs on the OpenWRT side could truly be a "Yun killer".

    ChrisZ

  • in ESP8266
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    Hello;
    Can anybody provide guidance as to the flash map, in terms of where to place the binaries, for a 1-Mbyte ESP module. I have several of these:
    http://wiki.iteadstudio.com/Wee_Serial_W­IFI_Module. They have the 25Q80 flash part mounted. After much flailing about I was able to program it as a 512-kbyte part. I am using the nodemcu flasher rather than the Python tool; this has never been a problem with the ESP-01. The first few attempts left me with a gibbering serial output that appeared to be dumping the memory. It was almost as if the preloaded AT firmware was still there in some vestigial form. After several misfires, changing the offsets, the Espruino 8266 binaries went in with all the default settings for the 1Mb/512kbyte part.
    Chris Z

  • in General
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    DrAzzy
    Thank you for the reply; its good to know which thing not to chase sometimes. I assume that making sure the board is not running at 16 MHz will also be critical to getting the USB working correctly. My goal is to get something running with an "Arduino Yun Shield" that is gathering dust; this requires that the serial port be on the shield connector rather than the ST-Link side. Trying to have a functional USB console after moving the jumpers around. Time to bite the bullet and set up a build environment.
    Chris Z

  • in General
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    Hi all;
    I am not sure if this is the best thread for this question but here it goes. Do any of the Nucleo builds have the on board USB enabled. I threw together a quick and dirty wiring harness to grab A12 an A11 off the morpho connector (with the pull up to DP) but cannot get anything to print to the USB port. All my attempts at writing to the USB come back with "undefined" error messages.
    With respect to the discussion above; I have been using ST Link to load Espruino on the non-official boards successfully for a while. However, with the last ST-Link firmware upgrade doing loads from my XP box became unreliable; ST-link loads from Win7 continue to work well. The mass storage loads have never been reliable for me.
    Chris Z

  • in News
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    Hi All;
    In response to the above; for some reason the link the nightly builds seems not to be working anymore. Likewise with Drazzy's 401 and 411 nightly builds; I cannot find anything past 3 June 2015 for those. I am probably just looking in the wrong place. There are always the v80 builds.
    Thanks,
    Chris Z

  • in Interfacing
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    Have you seen the "radiohead" library by Mike McCauley at
    http://www.airspayce.com/mikem/arduino/R­adioHead/
    He has made a library for the various Hope RF products that works on Arduino. There are also files in the latest release that allow the radiohead library to be built for the STM32F4 chips. I do not know the level of effort that it would take to port the libraries but it is at least an example of working code.
    Chris Z

  • in Tutorials
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    Hi;
    I will talk about a couple of hardware issues as I cannot provide any substantial help with the programming. Some USB power sources have internal current sensing that will cause them to sleep if no load current is detected. As a concrete example I have a rechargeable battery back that has two USB outlets (Ativa MobilIT 2400 mAh). When connected to the F3 Discovery board will all the bells and whistles it runs just fine. When I connect it to an Espruino with the HC05 Bluetooth module it runs fine for about 30 seconds and then shuts itself off. When I connect the same battery to an MSP430 Launchpad with a Bluetooth module I get the same shutdown behavior. In both the instances the battery pack decides it does not have a load. Given the amount of press from TI about the MSP430 being the lowest power processor on earth it is very entertaining that the Espruino gives it a run for the money!!
    For the soil resistance sensing there is a standard technique of reversing the current several times during one reading sequence. Set one pin high and the other as the analog input and accumulate the result. Reverse the roles of the pins and do it again; repeat this an even number of times so you have accumulated an equal number reads in each direction. Alternating like this will improve noise immunity against stray earth current and against surface differences in your pins by averaging it toward zero. There is also a concern that the nominal 40k pull down resistor at the inputs are not all equal; this scales your soil current into a voltage. I expect this would be equal on a given chip but vary from chip-to-chip. Alternating would average out pin-to-pin variations on a given chip but the repeatability from one chip to the next could be a problem. If you truly want to calibrate these it may be worthwhile to run a fixed resistor to ground from each pin and not use the internal one; for a one-off I would not bother.
    Cheers,
    Chris Z

  • in Tutorials
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    Sven;
    Thanks for the pics and the code snippet. I have a few more questions for clarity. Is there any kind of R-C network on your measurement pins now; either to ground or between the pins? It appears that you have a clean signal when operating from a "floating" battery supply and a noisy one when using a supply plugged into the wall outlet (referenced to local earth). Is that true? From your expanded comments my original comment about the USB source being the current limiter does not apply; your excitation pin is connected to the regulated 3.3 of the Espruino through the port pin (that is my reading). Is that a correct reading of the setup?
    Cheers,
    Chris

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