Output to hardware from RPI - Raspberry Pi Forums
this first real attempt @ control real rpi.
have 2 things want connect:
- 5v fan
- neopixel led/s
though fan can put straight across 5v, i'm wanting bit creative.
control fan comes on when needed / hot.
neopixel led/s, indication of going on in pi.
pi 3.3v, need buffer chip. believe sn74hc125n chip.
in articles reading 74hca125, or that.
sn74hc125n work?
next (smallish) question fan.... chip has protection diodes in it, there shouldn't worry fly-back fan?
attached basic circuit mean.
other pins on chip shown, taken connected needed.
have 2 things want connect:
- 5v fan
- neopixel led/s
though fan can put straight across 5v, i'm wanting bit creative.
control fan comes on when needed / hot.
neopixel led/s, indication of going on in pi.
pi 3.3v, need buffer chip. believe sn74hc125n chip.
in articles reading 74hca125, or that.
sn74hc125n work?
next (smallish) question fan.... chip has protection diodes in it, there shouldn't worry fly-back fan?
attached basic circuit mean.
other pins on chip shown, taken connected needed.
- rpi hw idea.png (6.01 kib) viewed 707 times
if want rpi switch fan on/off need transistor switching.
neo pixels need find special libraries can run neo pixels require precise timing of data line send data neo pixels , program running inside linux os program doesn't run in real time. there work around solution timing problem using dma , there few different libraries out there controlling neo pixels rpi.
neo pixels or more correctly called ws2812 or clone sk6812 need 5v on vin voltage input pin handle 0.5v 5.5v on din data input pin won't need , sort of converter convert 3.3v of rpi 5v. many people need 5v on din because vin must have 5v , vin won't run on 3.3v if read data sheet find the vin needs 5v , the din work fine on 3.3v how run them time.
wire neo pixels connecting high enough amp 5v power supply vin of neo pixel , wire rpi data pin neo pixel din common ground both rpi , power supply. don't power more few neo pixels off rpi 5v pin draw many amps , can damge rpi.
after there easier option, next generation apa102c leds have fourth pin clock pin don't need precise timing on data pin led chips read data input when clock line pulsed rather @ persific time. means don't need work around , can run them off rpi's spi pins normal python libraries
can buy apa102c few places , adafuit has re-marketed dot star can check them out too
neo pixels need find special libraries can run neo pixels require precise timing of data line send data neo pixels , program running inside linux os program doesn't run in real time. there work around solution timing problem using dma , there few different libraries out there controlling neo pixels rpi.
neo pixels or more correctly called ws2812 or clone sk6812 need 5v on vin voltage input pin handle 0.5v 5.5v on din data input pin won't need , sort of converter convert 3.3v of rpi 5v. many people need 5v on din because vin must have 5v , vin won't run on 3.3v if read data sheet find the vin needs 5v , the din work fine on 3.3v how run them time.
wire neo pixels connecting high enough amp 5v power supply vin of neo pixel , wire rpi data pin neo pixel din common ground both rpi , power supply. don't power more few neo pixels off rpi 5v pin draw many amps , can damge rpi.
after there easier option, next generation apa102c leds have fourth pin clock pin don't need precise timing on data pin led chips read data input when clock line pulsed rather @ persific time. means don't need work around , can run them off rpi's spi pins normal python libraries
can buy apa102c few places , adafuit has re-marketed dot star can check them out too
raspberrypi
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