i'm using atmega1284p control lpd8806 led strip. powering light strip , mcu separately common ground between them , lpd8806 data & clock pins connected pin 6 (mosi) , pin 8 (sck) respectively. i'm using 16mhz crystal oscillator 22pf caps ground, both pins 10 & 30 going 5v, , both pins 11 & 31 ground.
everything working correctly except seeing 16hz spike noise on other mcu pins connect data , clock pins of light strip. example, here's screen grab scope monitoring adc0 (pin 40):
and, zoomed in:
as can see, spikes on adc0 around 500mv, significant. i've tried adding decoupling caps across vcc gnd on both sides of chip (10 11, , 30 31), didn't make difference. i'm assuming source of signal spi communication don't understand how affecting other pins. measure spikes @ 61ms, it's right @ 16.4hz , consistent. appreciated, , please let me know if additional information.
thanks!
everything working correctly except seeing 16hz spike noise on other mcu pins connect data , clock pins of light strip. example, here's screen grab scope monitoring adc0 (pin 40):
and, zoomed in:
as can see, spikes on adc0 around 500mv, significant. i've tried adding decoupling caps across vcc gnd on both sides of chip (10 11, , 30 31), didn't make difference. i'm assuming source of signal spi communication don't understand how affecting other pins. measure spikes @ 61ms, it's right @ 16.4hz , consistent. appreciated, , please let me know if additional information.
thanks!
for example, here's screen grab scope monitoring adc0 (pin 40):other scope probe connected adc0?
Arduino Forum > Using Arduino > General Electronics > 16Hz spikes from SPI on ATmega1284p
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