SPI read while writing?

Question

I'm working on a driver for an SPI device that returns some data (device status) while the command byte is still being written. Is there a way to read this status data using standard Arduino APIs or do I need to bit-bang to access it?

Here's what the SPI signals look like:

SPI timing diagram

The 6 bits in red are the ones I'm interested in reading.

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For context, the device in question is a Microchip MCP3561 ADC (MCP3X6X series). It has a bug (erratum 2) where the new-data-ready flag (/DR_STATUS) is not always set correctly. Part of the work-around involves reading the status bits mentioned above.

Answer 1

The SPI.transfer() method is designed to send a byte through the SPI port and, at the same time receive an incoming byte.

Usage pattern:

uint8_t byte_to_send = ...;
uint8_t received_byte = SPI.transfer(byte_to_send);

• Alex Hajnal: Turns out the bug was elsewhere in my code. This works fine. Thanks!