Sotiris Lyras

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10 years, 9 months ago.

SPI Slave

Hello, I'm trying to initiate a communication with a spi master device, so the nucleo must be a spi slave device. The code I use, is the following one :

  1. include "mbed.h"

SPISlave device(PA_11,PA_12,PA_13,PA_14);

. . . .

but the compiler returns ERROR 20 and ERROR 18

Error: Identifier "SPISlave" is undefined in "main.cpp", Line: 7, Col: 2

Error: Expected a ")" in "main.cpp", Line: 7, Col: 22

What I'm missing here?

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2 Answers

Erik -
10 years, 9 months ago.

That error means SPISlave is not implemented on your device.

Sotiris Lyras
poster
10 years, 9 months ago.

Are you sure about that, is there any other way to use Nucleo (throught mbed) as an SPI slave device?

Just checked it, don't know which one you have, but for the F401: http://mbed.org/users/mbed_official/code/mbed-src/file/a7168c414ef2/targets/hal/TARGET_STM/TARGET_NUCLEO_F401RE/device.h. No SPISlave.

You could either make an SPISlave software implementation (so using only digitalins/outs), or make the code for SPISlave yourself (which I very well understand wasn't exactly how you planned to use it).

Main question though: Why do you need it? SPISlave on most microcontrollers is imo kinda sucky (so not the mbed implementation, but simply how they work on the microcontroller, where the CS line needs to be toggled after every word), but there aren't that many situations where you actually require one.

posted by Erik - 10 Mar 2014

I found the following code at the the library section

Reply to a SPI master as slave

  1. include "mbed.h"

SPISlave device(p5, p6, p7, p8); mosi, miso, sclk, ssel

int main() { device.reply(0x00); Prime SPI with first reply while(1) { if(device.receive()) { int v = device.read(); Read byte from master v = (v + 1) % 0x100; Add one to it, modulo 256 device.reply(v); Make this the next reply } } }

and an example here http://mbed.org/users/polytech01/code/TestSPIslave/file/cda27773d8b4/main.cpp

Do you know if this is valid code?

posted by Sotiris Lyras 10 Mar 2014

It is valid code, but not for your device, it does not support SPISlave currently.

posted by Erik - 10 Mar 2014