• STM8 timer

    K.C. Lee11/01/2018 at 00:46 0 comments

    This is a simple project:  STM8S003 timer for watering plants and LED lighting   It is essentially an clock project with a user interface for setting the alarms. The user interface is a missing piece in my microcontroller library and will be ported to my other projects.

    Here is the UI for trimming the RTC by adjusting the values of the timer reload.


  • Portable F103 - LCD

    K.C. Lee08/19/2018 at 20:29 0 comments

    Doing some reverse engineering of the LCD as I don't trust unknown 3rd party source code without knowing where they came from and more important how they got it and what LCD are they for.  Some of the low level settings are for a specific LCD type.

    Anyway, this is a quick test without the proper timing delays modified from my own Nokia 5110 LCD code.  That's a good start.

    Detail waveforms here: https://hw-by-design.blogspot.com/2018/08/portable-f103-lcd.html

    Main project page: https://hw-by-design.blogspot.com/2018/08/portable-stm32f103.html

    Sadly it is a blogging site, not project oriented.

  • Projects update quickies

    K.C. Lee08/16/2018 at 22:21 0 comments

    Cheap Xilinx Virtual Cable Alternative?

    Made a JTAG dongle using ESP8266 module.  Based on https://github.com/gtortone/esp-xvcd, but I made some changes to GPIO pins and added proper level translation.

    Haven't started with the firmware.  At some point I'll be removed the Arduino digitalwrite() junk as the abstraction are badly and sloooooooow for bitbanging.  

    Sneak peek at the 1 sq. inch layout if and when I am happy with the design.

    The $20 FPGA board has arrived (18th Aug) from China.  It took a bit of damage with the JTAG pin sticking out and slightly bent.  Canada Post put the package in a a big Canada Post plastic bag.

    The PCB side by side with a "credit card".

    portable f103

    PCB arrived from OSH Park a couple of days ago.

    Aside from the stereo connector a bit longer pushing into a couple of parts and a bunch of soldering mishaps,  things are looking okay.  I am in the middle of writing driver code.

    Smart bench supply

    A couple of modules and some plastic knobs showed up in the last couple of days.

    The C$ 2.58 buck-boost one has a possibly XL6019 (180kHz) relabelled as XL6009 (400kHz).  I saw 180kHz switching waveforms on my scope.

    Compare the texture of the one on the left vs the one on the right hand side (fake).  The fake one has some fine scan lines vs the textured surface on the left

    There are a couple of possibly fake or obsoleted ELNA labelled cap.  The ripple (lol 200mV) does not match their claim of 30mV even at low load.  They do have decent inductors.

    The C$ 1.78 XL6015 (180kHz) buck module is probably using real part as I see 188kHz on my scope and the ripple is actually decent.  The inductor is getting warm - they probably use the wrong type of core that is too lossy.  Might move inductor from the buck boost module here.