If a Pi hat wanted some CMOS bytes..

If a Pi hat wanted some CMOS bytes how would it choose?

A legacy podule can call Podule_ReadInfo to find the address and number of cmos bytes allocated to it but a pi hat can’t do that, and if it could what podule would it be?

At the moment I am thinking of asking my RISC PC what CMOS it gives podule 8 the ‘Network’ socket as this seem conceptually closest to the hat. Taking that address and finding its equivalent in the RO5 cmos layout and using that.

In the same vein if the hat had its own eeprom meeting the hat specifications for linux driver identification, can that iic bus be accessed from RISC OS?

At the moment I am thinking of asking my RISC PC what CMOS it gives podule 8 the ‘Network’ socket as this seem conceptually closest to the hat. Taking that address and finding its equivalent in the RO5 cmos layout and using that.

Best not to randomly re-assign something already allocated. Direct your query to ROOL.

If a Pi hat wanted some CMOS bytes how would it choose?

Does it need to be able to access some sort of configuration prior to the OS having started up? If it can be done a little bit later (obvious question – how would the driver module be loaded?) then you can just read something out of Choices instead of worrying about CMOS.

linux driver identification, can that iic bus be accessed from RISC OS?

I have no idea what the Linux spec is, however I have a CJE Power Control module and a dinky OLED hanging off the IIC that’s up the top end of the expansion connector (near the 3.3V, 5V, Serial). If it’s the same, then yes, RISC OS can use it.

Why do you need it to be NVRAM?

Your software is loaded from disc, so your configuration might as well be as well. Using the Choices system to configure the component is far more appropriate for software that is not present within the ROM system. The only real reason to use the NVRAM is so that you can start up in a way that does not require a disc (or is required in order to locate a disc), but since you’re not in that situation, just load the data from Choices, or if you’re a module, provide * commands or system variables to configure the component and a configuration tool to write them into the choices system.

> Why do you need it to be NVRAM?

I think I was being incredibly thick and just stuck in the past.

The other Econet related config I am reading, (station number and protection bits) are in the CMOS so I guess I was just following that pattern and needing somewhere to store clock enable and rate I started to wonder how former expansion card support for per podule CMOS maps to a pi.

Settings stored in a file and editable by some choices mechanism is clearly the way to do it nowadays.

> hanging off the IIC that’s up the top end of the expansion connector.
No its not that IIC bus its the one at the opposite end of the connector.

Nice to know that at least one of them is accessible though.