Tibbo Ethernet shield

[HenrikOlsson]

Exactly, but they don't mention you can't share the CLK line with others on the bus (if you go with the NAND gate aproach) which means you need a second CLK line and the pin you gained by using the NAND gates is gone. So, if you have more than one SPI device on the same CLK (like that memory device) it seems to me that it would be best not to go with the NAND gate aproach.

/Henrik.

[dhouston]

I already knew I could neither share the CLK nor DI/DO - they've hard coded all of this which sort of defeats the whole concept of SPI.

[HenrikOlsson]

Hi Dave,
The way I understand "hardcoded" or "non remapable" in this context is that you can't choose which pins on the EM500 to use as CLK etc but surely you must be able to USE the "fixed" pins to communicate with other SPI devices on a bus as well? Ie share the clock, and SDI/SDO pins among multiple devices on a bus (as long as you take care of the reset line that is).

Are you saying that they have hardcoded the SPI CLK line to one specific pin when using the "GA1000 object/library" or whatever they call it and ANOTHER pin when using whatever "object/library" is needed to accessing the memory or any other external SPI device?

If so perhaps the GA1000 needs exclusive interface to EM500, perhaps the "GA1000 object/library" polls the GA1000 at certain intervals and therefor you can't tie up the SPI bus with other tasks. Ah, what the heck do I know I'm just thinkin out loud.

/Henrik.

[dhouston]

Are you saying that they have hardcoded the SPI CLK line to one specific pin when using the "GA1000 object/library" or whatever they call it and ANOTHER pin when using whatever "object/library" is needed to accessing the memory or any other external SPI device?

Exactly. Based on Tibbo's documentation and an exchange of email with Tibbo Support, this is how I MUST connect the GA1000 and Flash. I've edited the earlier diagram to reflect the latest changes to pin assignments which I hope will now be stable. They should call it IbS.

[dhouston]

I have revised the PCB layout to agree with this week's interconnect diagram from Tibbo. We'll have to wait to see what next week brings.