2016-10-24

Logitech M310

Since replacement mouse wheel encoder for my A4Tech X-710 turned out to be almost as imprecise as old one and it's USB cable has lost almost all isolation exposing wires (I guess chemical decomposition over time) and plastic cracked a little next to screws it's time to change mouse.
I've bought refurbished Logitech M310 for $12.
First impression:
  • it's "full size" mouse and it turns out it's very similar in size and shape to X-710
  • left and right button are nice but little louder than in A4Tech
  • middle/scroll button is slightly hard to use requiring some force to be pressed and pretty loud
  • scroll wheel moves quietly and with little resistance although still seems to be precise (contrary to opinions I've found on micro-precise scroll used e.g. in M325)
  • off-center optical sensor probably needs some time to adjust to (sensor in X-710 was placed exactly in the middle)
  • mouse feet seem inferior to those (thicker and 6 instead of 4) in X-710
  • mouse worked out of the box (I'm not sure if paired earlier or does not require pairing), no software installation was necessary with Windows 7 
Because of asymmetric optical sensor location I wouldn't recommend it for people using left hand (or both hands) - when using with right hand it feels like it has lower dpi than X-710 (i.e. less than 1000) while using with left hand it behaves very strange. It must be related to anatomy - when rotating mouse with right hand cursor moves only a little (this is fine) while when rotating even little with left hand cursor moves whole screen length.
If you are using windows consider turning off "Allow this device to wake up the computer" option in device manager to not be surprised with accidental waking up of computer. Useful commands:
  • powercfg lastwake - check reason of last wakeup
  • powercfg -devicequery wake_armed - list devices allowed to wake PC
Although producer recommends alkaline cell (i.e. 1.5V cell) it works fine with charged NiMH eneloop 2000mAh cell. With my use (5-6 hours on work day, more on weekends, no ON/OFF switch used) it worked 2.5 months from this cell, down to 0.945V.

I am not noticing optical sensor performance drop after switching from X-710 which is probably good thing. I'm using cloth mouse pad thus these are not challenging conditions though.




Damage on button plastic was caused by using aggressive solvent for cleaning microswitch and not waiting for it to dry

Nordic NRF31512C

Surprisingly (I had no issues with similar microswitches in X-710 for 10 years) left microswitch started generating double clicks after about year of use. At first I've tried to clean it using few drops of solvent, but it seem to help only temporarily. Next step was opening microswitch, cleaning dirt from "hammer" area:
There are very small grooves on left and middle prongs holding springy element with hammer in place thanks to tension. If microswitch cover would not be removed very carefully spring may jump out of these grooves right away.
See also: https://electronics.stackexchange.com/questions/29955/how-do-i-fix-an-omron-d2fc-f-7n-microswitch-from-unwanted-clicks.


2016-10-11

Saleae logic analyzer clone

 Popular sub-$10 clone of USBee AX Pro / Saleae logic analyzer. Works with sigrok under Windows and under Linux (may require using unofficial package repository for ubuntu 14 or older). As open source firmware is used with sigrok there seems to be no copyright violation.
See also:
https://sigrok.org/wiki/MCU123_Saleae_Logic_clone
https://sigrok.org/wiki/MCU123_USBee_AX_Pro_clone
One of the limitations is incompatibility with 1.8V logic.
 Build quality might have been better as with one I bought case latches were not closing because LED diodes positions were not matching cuts in top cover.

USB cable from the set I've received is not working consistently, I'm using other one, probably higher quality with this logic analyzer.

2016-10-09

ST-Link v2 clone

Popular cheap ST-Link v2 clone from China


STM32F101CBT6 is used instead of STM32F103CBT6 that may be found on "regular" ST-Link v2. Fun fact: STM32F101CBT6 does not officially has USB device.
See also: https://github.com/blacksphere/blackmagic/issues/62


Board markings MX-LINK V2 2016-01-18.
ST-LINK recognizes it as firmware version V2J21S4 and shows serial number.


I have also slightly older ST-Link clone with different pinout:
This one has only single LED. Again, STM32F101CBT6
There are four PCB points for manufacturing purposes, in order: SWD, GND, SWCLK, +3.3V.
There was no isolating foam on the "bottom" side like in newer version - I would recommending adding one to avoid short to aluminum case and/or between PCB pads.
ST-LINK Utility recognizes it as "Old ST-LINK firmware/ST-LINK already used" (no serial number?), firmware version V2J17S4.