Using Spi to talk to external expansion unit

[Matt]

Hi,
I am creating an external expansion board for the pi  that I would like homegeni to communicate with via SPI. I can't seem to find an example code to do this.  Can someone please share a link or some code using the rasberry pi SPI port.

Thanks
Matt

[Gene]

One example could be EdenV2_Module_1_1.hgx available from:

https://sourceforge.net/projects/homegenie/files/testing/

this is used to talk to arduino via SPI. Also the arduino firmware is available for download.

Cheers,
g.

[NickP]

I just added a driver for the PiFaceDigital device to the genielabs raspberry-sharp-io. If Gene is happy it will get pulled in.

The driver uses native SPI to control the MCP23S17 port expander at the core of the PiFace.

[Gene]

Merged. I will update HomeGenie as well soon.
Thanks!

g.

[Gene]

I also forwarded a pull request to the raspberry-sharp-io master.
In the meantime, a couple of days ago, my fork was already integrated into the master, so you could have pulled in there.

Cheers,
g.

[NickP]

Thinking through this again; I believe it makes sense to create an abstract MCP23x17 class and derive MCP23017 from it (without breaking the current interface) then also derive an MCP23S17 (SPI ) class as well.

Updating the components that currently accept an MCP23017 to accept MCP23x17 would still work for existing code ( MCP12017 being a derivative) but also allow people to use MCP23S17 as well.

What do you think?