Linearizing an LED for 800 pwm steps'?

[Mike, K8LH]

Hank,

You got a 12F683? If so, and if you want to experiment, connect an LED to GP0 (anode) and GP5 (cathode) and try the program below. The circuit doesn't use a current limiting resistor, relying instead on the RDS(on) resistance of the I/O pin output FETs.

The program fades the LED through sixty four gamma corrected brightness levels spanning 256 1-usec BAM duty cycle steps with a 1280-usec frame rate (781-Hz refresh rate).

:020000040000FA:0600000083018501F128D7
:08000800F000030EF10083017A
:100010000A08F2008A010408F3008C1074088500B5
:1000200083167608850077088500162878088500ED
:100030000030FF3E031819281D287908850002307A
:10004000FF3E0318202824287A08850074087407C6
:1000500074191030F41A0130F4000430FF3E031814
:100060002E28322800007B0885002030F418243028
:1000700074192830741A2C30F41A303084000C3083
:10008000FF3E031840287C0885007D08F5007409B0
:10009000F600F700F800F900FA00FB00FC00FD0094
:1000A0000130741820300018F6068018F706001981
:1000B000F8068019F906001AFA06801AFB06001BDA
:1000C000FC06801BFD06840A0230F418203000185C
:1000D000F6068018F7060019F8068019F906001AC6
:1000E000FA06801AFB06001BFC06801BFD06840A2C
:1000F0000430741920300018F6068018F70600192D
:10010000F8068019F906001AFA06801AFB06001B89
:10011000FC06801BFD06840A1030741A203000187B
:10012000F6068018F7060019F8068019F906001A75
:10013000FA06801AFB06001BFC06801BFD06083031
:10014000FF3E0318A0287508850073088400720814
:100150008A00030E8300F00E700E09008A013F39F9
:10016000820700340134023402340234023403348E
:1001700003340334043404340534053406340634BB
:1001800007340834083409340A340B340C340D3481
:100190000E340F3411341234143415341734193426
:1001A0001B341D341F342234243427342A342D3494
:1001B0003134353439343D34413446344B345134A0
:1001C00057345D3464346B3472347B3483348C3410
:1001D0009634A134AC34B734C434D134E034EF3481
:1001E000FF340730990083169F0170308F000F1D78
:1001F000F72883123F30840080018403841AFC288E
:100200002030F4000130AA000230AB000330AC0013
:100210000430AD000530AE000630AF000730B0004E
:100220000830B1000930B2000A30B3008C019101EE
:100230000530920083167F3092008C148312C030F8
:100240008B0010303321B60A361B2C293608AE201D
:10025000A000212910303321B603B61B212936080E
:10026000AE20A0002A29B500740820393406B4064F
:0C027000340503193429350B332908002C
:02400E00D43F9D
:00000001FF

I'll also write something using the PWM module so that we can try 125-nsec PWM steps (with an 8-MHz clock).

Cheerful regards, Mike