Response to Gran Turnio
June 18th, 2009CLOCK ESCAPEMENT
February 27th, 2007Here is a look at my Verge & Foliot escapement
in action
ADVICE ON CMOS IC’s
August 9th, 2006THIS IS A LETTER I SENT
to George Gallant, Jim Morris
and Jim Fiske
hi
just realized something troubling
I was reading some hints for using the PIC
microcontrollers and found this:
“unconnected port bits should never
be set up as inputs”
“when floating, CMOS inputs can flip rapidly
between states and cause excessive current draw,
heating and even damaging the PIC”
So – set all unused bits of ports to outputs.
I went back to one of my books talking about
CMOS IC’s and noticed this warning:
ALL unused inputs MUST be connected to Vdd(+) or Vss(gnd)
otherwise erratic chip behavior and
excessive current consumption will occur.
other rules for CMOS were NEVER connect
an input signal to a cmos circuit when
the power is off.
another curious warning was to
avoid slowly rising and falling input signals
since they cause excessive power
consumption. it recommended
rise times faster than 15 usecs
I think I have been lucky so far
but I’m certainly going to observe
these precautions.
Regards.
Larry Keegan in Stoneham, MA
ALPHANUMERIC DISPLAY AND KEYBOARD
May 26th, 2006Do you realize you can pick up older keyboards for one dollar! I have a few and use them to interface with my computer chips. I have done more work on my alphanumeric LCD (liquid crystal display). I can now set addresses and send ascii characters to these locations. The lcd controller automatically increments or decrements, each time you write to an address.
SONG MAKING CIRCUIT
May 26th, 2006Here is a version of a circuit that plays music. The program actually calls subroutines called doe,ray,me,far,sew,la,tea,doo. I have done lots of pgms on generating sounds, but this one attempts to get accurate mnotes of the musical scale. Some of the ideas came from an artice by G. Y. Xu in Nuts & Volts magazine.
So far this circuit plays Westminster Chimes and the theme played a race tracks for the start of the race. My circuit plays the notes as regular tones or as bell chimes.
PARALLEL & SERIAL MEMORY CHIPS
April 29th, 2006
KEYBOARD INTERFACE FOR MICROCONTROLLER
February 26th, 2006Here is a look at how I am hooking up a PC KEYBOARD to my microcontroller – the PIC16F628.
I found an article on the inernet that explained the protocol of a PC keyboard. Not as bad as I thought! Only 2 lines for CLOCK and DATA. Other 2 lines for +5 volts and a return. The keyboard sends serially, but not the asciii codes themselvesw, but scan codes, which have to be translated. I had to do a lot of debugging of my code but I’m having success now.
I can also display alphanumeric data on my LCD, make it blink, and have it rotate across the screen. Much fun!!
ALPHANUMERIC LCD DISPLAY
February 9th, 2006SUCCESS with programming my alphanumeric LCD display!!!
WATER ON STONE
January 27th, 2006can’t feel the rain on their face any morecan’t go to warI pass the stonesone by one in the storm
and when the rain has stopppedthere’s no need to warmin the sunwhat’s done is done
but the rows are alivewith memories. This onetraveled here, this one thereone breathed his lastin Normandy air
whether it’s spring, or rosesdoesn’t mean a thingnone of them is aloneonly me, watching wateron the face of a stone
Larry Keegan
STEEPLES
January 27th, 2006it’s Saturday night and all is wellnobody’s going to heavenand nobody’s going to hell
there’s road rage on the highway600 waiting on death rowfor some the spring is comingfor others – I don’t know
there’s a war that’s killed ten thousandit started because no one said nosome hope it will turn out wellthere were lies, and a command to go
it’s Saturday – people head to churchon Sunday they will say their prayerssteeples make good cell phone antennasmillions bow their headsbut there may be no one upstairs
Larry Keegan