The content of this blog is my personal opinion only. Although I am an employee - currently of Nvidia, in the past of other companies such as Iagination Technologies, MIPS, Intellectual Ventures, Intel, AMD, Motorola, and Gould - I reveal this only so that the reader may account for any possible bias I may have towards my employer's products. The statements I make here in no way represent my employer's position, nor am I authorized to speak on behalf of my employer. In fact, this posting may not even represent my personal opinion, since occasionally I play devil's advocate.

See http://docs.google.com/View?id=dcxddbtr_23cg5thdfj for photo credits.

Sunday, June 21, 2020

ISO bicycle turn signal SYSTEM - wireless controller, pairable with multiple signal lights/colors/

I love bicycles: in my younger days, road bikes, then touring and cargo bikes, now an e-bike

My rides always involve busy roads that have no shoulders, steep hills (coasting speeds > 30mph) , crossing traffic lanes, often only 1 lane in each direction,  and no protected crossings where I need them.  I feel that I need a rearview mirror and turning signals.  This post is mainly about turning signals, although 

While it would be great if the turn signals could connect to the eBike batteries. That's not a requirement. Lights with batteries, or, better, USB rechargeable, would be fine.   

Wireless turn signal controls are all over the web, including Amazon. As far as I can tell, the wireless bicycle turn signals that I have found via Google and Amazon have one controller, and one or two signals.  There is no ability to pair extra signal lights to the same controller.
It seems to me that it should be possible to have a SYSTEM of wireless turn signals for a bicycle.  

A wireless turn control mounted on the handlebars or nearby.

Multiple sets of lights - not just 1 or 2, but

Multiple sets attached at different places on the frame.   
  • E.g. on the rear so that not hidden when I am carrying a full load of cargo; 
  • on the seatpost; 
  • on the handlebar ends; 
  • possibly integrated in rearview mirrors mounted on handlebar ends
  • Less common
    • ?pedals?
    • ?front facing turn signals?
    • sideways -- e.g. wheel lights.
Different colors: amber, red, etc.

Different turn indications: flashing, arrows...  Heck, I would like an "I am slowing down indicator" when I am descending a steep narrow road at speed, with a car right behind me.

Different attachment styles.  E.g. rings suitable for seatposts and handlebars; handle ends; velcro straps for my e-bike, which doesn't have the thicker posts where such lights would need to be.

As with any such battery driven lights, redundancy - two lights, either side, either direction - would be best, for the case where one battery runs out.  Quick release to make it easy to charge them at home or office, plus to protect against the theft of the accessory light, as when parked at grocery store.

Friday, June 05, 2020

If only we could donate platelets every 6 days rather than every 7 days

During COVID I have been trying to donate platelets every  week.   The Red Cross  requires  at least 7 days between donations.

It is a pity that this minimum spacing cannot be every 6 days. I can really only donate on weekends,  Saturday and Sunday.  But if I donate on Sunday  one weekend I cannot donate on Saturday the next week -  too close.   The only way I can  switch back to donating on Saturdays  is to miss a week. 

Does it really make that much of a difference?


Imagine that  on even weeks I can donate on Saturday but on odd weeks I can good donate on Sunday.   With the 7 day rule  the number of donations I can make is reduced by 33%,  compared to being able to donate every week  as would be allowed if the  separation were 6 days.  That's more than the 1/7th  you might  na├»vely expect.

Such phenomena of quantization are common in computers. E.g. on P6 our  4 cycle FP multiplier and 3 cycle FP adder shared a pipeline.  If we had not stretched the latency of the adder  to 5 cycles we would have lost a lot  of compute bandwidth.