Posts: 3
Joined: Wed Jul 24, 2019 12:41 pm

Connection to DAC/ADC with SDIO

Fri Aug 23, 2019 9:26 am

I am attempting to connect a DAC (DAC1220E) and ADC (MCP3550) to the raspberry using the SPI. The DAC uses a single port for data transfer (in and out), the ADC only has a port for OUT/RDY. I looked into activating the bidirectional mode on the RPI4, but could not find a clear route for this.

Is it possible to set the SPI interface to bidirectional mode on the RPi4? More concretely: can SPI1 (3 CE) be turned on to birectional mode?
How do I enable this function?
Alternatively, is it possible to interface MOSI/MISO ports directly to a SDIO?

Any suggestions and help are greatly appreciated.

Links to datasheets:
DAC: http://www.ti.com/lit/ds/symlink/dac1220.pdf
ADC: https://pdf1.alldatasheet.com/datasheet ... P3550.html

Posts: 37
Joined: Tue Feb 19, 2013 5:31 pm

Re: Connection to DAC/ADC with SDIO

Mon Sep 09, 2019 5:13 am

I don't understand your question. SPI is inherently bidirectional -- whenever you write a byte, you also read a byte. On an ADS1256, while writing the configuration you ignore the bytes it sends to you; once you have told it to send the data, it ignores the bytes you send to it.

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