SPI Slave Sketch Example

[Nbelles]

Hello,

I have not used the SPI interface much at all and definitely not as a slave and am looking for a simple example writing data from the master to the slave. I have found some examples for generic Arduino's around the internet but I'm not sure that they work with this core. Any help would be greatly appreciated.

Thanks!

[SpenceKonde]

Spi slave on arduino is hard to pull off within the arduino api. It must be implemented dmanually (look around, nobody else has an spi slave library either. You've got to do it manually (for example, attached interrupts are dead before the arrived, because if you are calling a function that it can't inline, from the isr, the interrupt overhead is such that the timing constraints at typical spi clock speed simply cannot be met. Even with tight hand written isrs, it's tough. The core of the problem is thst you can't clock stretch like i2c and to compound thst issue, spi clock speeds are often higher. Even with buffered mode and manual interrup, if the sck clock isn't on the low side, it's just not going to work because the arduino can't get data into the buffer before the master tries to clock in or out the next byte. I recommend wire slave, usart, or basically any other means of communication unless you are a real wizard, and/or are flagrantly abusing the spi module (as in, you're slave, but you're just using it as a shift register and being your own master, combing with evsys and ccl to to output those weirdo custom.protocols.

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On Tue, Jan 24, 2023, 00:56 Nathaniel.Belles ***@***.***> wrote: Hello, I have not used the SPI interface much at all and definitely not as a slave and am looking for a simple example writing data from the master to the slave. I have found some examples for generic Arduino's around the internet but I'm not sure that they work with this core. Any help would be greatly appreciated. Thanks! — Reply to this email directly, view it on GitHub <#901>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABTXEW2SPYGB5ZKKIPMHYXDWT5VIRANCNFSM6AAAAAAUEVUHCM> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[Nbelles]

Sounds good, I'll stick to I2C then. Thanks for the info!

[SpenceKonde]

That's a wise decision.

SPI slave mode is something that should be used only in extreme applications.

I2C for master-slave communications in normal applications, and UART for peer to peer communications under normal and most abnormal applications.