low frequency generator

[matrix1233]

hi,
what is the correct method to do a low frequency generator (1hz .. 500khz) on raspberry pi ?

thanks

[joan]

How will you measure correctness?

If you only want one or two channels the answer is probably use the PWM peripheral.

See http://abyz.co.uk/rpi/pigpio/pigs.html#HP

[matrix1233]

hi,
but how can i know the frequency generated ?

[joan]

hi,
but how can i know the frequency generated ?

I don't understand.

You set the frequency.

Do you mean how do you know if the frequency is being generated properly?

[matrix1233]

hi,
for example on the gpio 18 i wanna to generate a frequency = 3 khz .. can you give me an example to do that
thanks

[joan]

hi,
for example on the gpio 18 i wanna to generate a frequency = 3 khz .. can you give me an example to do that
thanks

pigs hp 18 3000 500000 # GPIO18, 3000Hz, 500000/1000000 dutycycle (50%)

[MarkHaysHarris777]

hi,
for example on the gpio 18 i wanna to generate a frequency = 3 khz .. can you give me an example to do that
thanks

see this link.

Code: Select all

## Import the necessary header modules
import RPi.GPIO as GPIO

## Setup the GPIO for PWM on pin12 {GPIO18}
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)
p = GPIO.PWM(12, 300)
p.start

... that code will generate 300Hz ... change 30 to 440 and get concert A. ... change to 30000

for 30KHz

[matrix1233]

it work thanks
can i combinate 2 frequency for example 3 khz and 125 Mhz on the same output on the gpio ? ( see the picture )

[joan]

I'm not sure. The PWM hardware might be programmable to do that, but my hardware_PWM function does not support that mode.

Why? That looks vaguely like an IR remote control signal. I.e. you have a high frequency carrier switched on/off in pulses. What are you trying to do?

[matrix1233]

hi
am trying to do a personalised frequency generator where i can program all possibility of signal output

[joan]

hi
am trying to do a personalised frequency generator where i can program all possibility of signal output

At anything over a megahertz you are going to have to program your own solution.

Have a look at the PWM / PCM documentation in http://www.raspberrypi.org/documentatio ... herals.pdf

For sub-megahertz pigpio waves might work.

http://abyz.co.uk/rpi/pigpio/cif.html#gpioWaveCreate