APA102 ... what is it ? find nothing in the store ... RGB LED light strips ...40X2 ???

max.well

New Member
in the \samples\BASIC directory is \APA102 ... 40X2 ... and 8 code examples for a 40X2 that drive led light strips.

yet i find no further info on what led light strips the code is for. or what the hspi commands go to.

i expect there to be some sort of controller the 40X2 code talks to. that in turn connects to led strips.

if you know anything that will help me get going in that direction please lend a hand
 

premelec

Senior Member
Welcome to this forum... please use the Internet to find the basic APA102 drive functions. The archive search function for APA102 applies to any light strips that use these units. 4 Wire connections - V- V+ Data & Clock. For the APA102 you can drive them directly from PICAXEs as they have loose timing requirements and don't require critical timing like many other RGB LEDs require. I have successfully driven APA102s with 08M2 PICAXEs... at slower clock speeds...
 

max.well

New Member
Welcome to this forum... please use the Internet to find the basic APA102 drive functions. The archive search function for APA102 applies to any light strips that use these units. 4 Wire connections - V- V+ Data & Clock. For the APA102 you can drive them directly from PICAXEs as they have loose timing requirements and don't require critical timing like many other RGB LEDs require. I have successfully driven APA102s with 08M2 PICAXEs... at slower clock speeds...
ok , premelec , thanks for your reply , see now my error . .. to focus solely on this site's store
for leds the 40X2 sample code talk to to. tunnel vision .

now , after a stroll thru the 'net , the new situation is too many choices. so now ask if you have any suggestions for a vendor that sells good 30 led / meter strips ?
light too , as the app'n is on my 2m RC night flyer.

and the data for the chips on these strips. is there any you've found that is well-written with good ex's
or any summary introductory tech on programming them. for instance that 40X2 code contains a bunch
of 'macros' for which i have no experience. and to begin with dont understand their usage. and whether
some other form of code like a call/return subroutine wouldn't work as well

no hurry with this. just whenever you get around to it
max.well
 
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max.well

New Member
Circuit for connecting apa102 LEDs to a 28X2.
View attachment 22474

Bill
Bill , you added greatly to my hobby life with your reply and circuit sketch.
the sketch held many features not previously known. like a /RST pin on a pic.
i'd thot they were done away with on newer pic uC's.

and the 10K and 22k R's on the program port. they affirm recent findings as rev-engr'd
a 027 PCB circuit. also note the 3 10k pull-down R's on the A pins and will be
thinking about what they are for.

btw did you use some PIC s/w to draw this circuit ?
what stands out are the part symbols. for its ease of use and PCB prices i play with the Easyeda
PCB s/w and would like my circuits to look as informative as yours does.

the other respondee to my 102 post , premelec, was asked about a vendor recomendation for
some 102 strips. and i want to ask you the same thing. 30/meter ones that are light in grams.
for a RC night flying applic'n. and a rec'n too for some good and readable tech data for the
led chips on these strips. and lastly if you have any code for a 102 strip that does not use macros.

last is to say that this 102 discovery led to looking here in a box on the shelf of some strip
leds bought a few years ago. they have 4 wires. and lit up nicely with a 12V batt w/ their controller.
using my 1054 rigol 'scope on the 3 rgb lines led to popping the fantasy bubble that they were
this newer 102 generation of strips. the signals were all PWM. this means doing some shopping

go to 0:42 and see the dazzling pattern these 102's have been programmed to do on a 2m plane
aloft after dark.

at 180+ $ the e-flite Night Radian is a bit pricey so am planning on get the plain-jane Walrus
from hobby-king and cutting grooves in the foam wing for some 102 strips

max.well
 

premelec

Senior Member
Not clear if you've dug up the data on APA102 - http://www.datasheetcafe.com/apa102-datasheet-smd-rgb-led/ is a site that helps... basically you need to send 4 bytes [32 bits] for each pixel in the string. How you determine to send these [bit banging with a subroutine in chips without SP protocall like 08M2s] and what sequence is the art of programming to your desired result... I didn't use any macros but did use a subroutine putting the byte to be put out in the same variable [e.g. b0 bit0-bit7] and sometimes storing the sequence memory before initiating output rather than computing it out for each pixel. It's been a few years since I worked with this... there were several examples of code in this forum's archives...
 
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