Raspberry Pi Forums

Hi
I have been working on this project where i have interfaced the RPi-3 with the ADC and ADC is generating clock,chipselect and data .
how to capture this data at the falling of the clock via the GPIO?

You could cast a magic spell.

Alternatively if you tell us the type of ADC we might be able to offer advice.

Hi
Here are the details on the ADC i am using when interfaced with RPi
The ADC works in two modes : Master and Slave mode
to configure the ADC in the respective mode i am using SPI0 i.e register write/read using SPI0.

If the ADC is configured in master mode it generated clock,chip_select and data.
The frequency of clock ranges from 750KHz to 24 Mhz
chip_select frequency ranges from 10khz to 375khz respectively
My aim is the capture the data from ADC to the RPi via the GPIO.

I configured the ADC in slave mode and interfaced it with SPI1 for data capture , unfortunately the chip_select frequency was not constant hence i got junk data .

And Rpi can only act as master in SPI protocol ,so for data capture i cannot use SPI and only option i have is to use the GPIO and sample the data from the at the falling edge of the clock with chip_select being low .

vybhav wrote: ↑

Tue Aug 14, 2018 8:04 am

Hi
Here are the details on the ADC i am using when interfaced with RPi

I think posting the exact model and / or link to data sheet would be more useful.

I wish i could share the datasheet ,but due to confidentiality clause i am not allowed to share. Please let me know the specific details you are looking for ,i will try my best to share it.

If you want help we need the model number.

please find the data sheet here: http://www.analog.com/media/en/technica ... 7768-4.pdf

How many channels do you intend to use at what sample rate, for how long?
What do you intend to do with the data? at 8 channels and 110kHz that's 2.64 Mbytes/s which may be possible but I think you would have to sample asynchronously and find the sync pulses in the data. You might also need to de-serialise the 24 data bits over 8 channels.
110,000 * 24 bits = 264000 bits/s and you need a sample rate at least twice that

You could start with Joan's piscope which will grab the states of multiple gpio at up to 1 MHz, I think.
That will demonstrate if the Pi can capture the raw data for a short time.