ZX-24n SPI slave /CS pin?

[GTBecker]

OpenSPISlave documentation doesn't explicitly list the SPI slave mode CS pin for ZX-24n. Assuming that's an oversight, is it pin 6?

[dkinzer]

OpenSPISlave documentation doesn't explicitly list the SPI slave mode CS pin for ZX-24n.

The slave select pin isn't listed for the ZX-24n because you can't really use it as an SPI slave unless you modify the board (see earlier discussion). If you do modify the board so that the on-board EEPROM no longer sees the slave select signal, then you might have access to the signal at the hole along the end of the board by pin 1.

[GTBecker]

Thanks. I guess I'm fading - since I participated in that thread. In my own defense, though, I'm drugged, post-major-dental-work. Ugh.

[GTBecker]

On this ZX-24n I opted to sever SO from the EEPROM by lightly drilling off the via at the bottom of the M of MISO.

[GTBecker]

I am struck by Netmedia's prescience.

The seven through-holes on the top edge of the ZX-24n, whose function was defined by the BX-24, are all (and, in my tracking camera implementation, only those are) used to interconnect two ZX-24ns as an SPI master/slave pair. The only exception is that I bridged a header pin over the Vcc connection to the adjacent Vin pin 24 to supply 12v for the camera that the slave mounts. The resulting seven-wire umbilical between the two processors couldn't be cleaner.

I've often used the inner three SPI connections but never any of the others, let alone all seven. 10 years after the fact, my congrats to Netmedia - and thanks to Don for keeping them.

[dkinzer]

I am struck by Netmedia's prescience.

Necessity, who is the mother of invention. (Plato) Except for the SS pin (near pin 1) the pins across the end of the board are needed for manufacturing test. I suspect that they (Netmedia) added the SS pin to allow pre-programming and/or reading the onboard EEPROM; it isn't needed for programming the AVR.

[GTBecker]

Now that you mention that, I see that the same pinout exists on Netmedia's LCDX.



Tom