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SPI - one-way communication Slave->Master

Question asked by pz on Jun 9, 2015
Latest reply on Jun 10, 2015 by pz
Hello everybody,

In my current project I need to establish an SPI connection between an STM32F407 microcontroller (slave) and an AD7763 A/D converter (master). Before the ADC actually starts sending any data, its two registers need to be initialised. The microcontroller must first send a total of 64 bits without getting any feedback, which basically means it needs to work in some kind of one way slave to master mode. I know this is against common standards, as generally one direction SPI communication works the other way around, but my question would be - is it doable at all? If yes, does it make sense to try to implementent it, or are there any easier/better solutions?

At the moment I'm trying to send a single byte from the slave to the master, but it keeps being sent continuously instead of only once. I have tried setting an SPIx->DR = 0x00; command in my function to set the register back to 0 after the transmission, but it still does not fully solve the problem - data is sent two/three times instead of once. This is probably due to the transmission's high speed (frequency = 20 MHz).

Thanks in advance for all your inputs/suggestions/examples.

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