Shared PINs (IIC port J4)

[This N°9]

First the good news: the FRAM-module (http://www.midibox.org/forum/index.php/topic,12641.0.html) is running (tested with the slower mios_iic so far, tests with the 1MHZ driver will follow).

I noticed that it's not possible to stretch a session (begin -> write -> write -> end) over multiple Tick()'s, which seems logic if I see that J4 SC is a shared pin.

My question: which function calls will use the J4 pins? For ex. MIOS_LCD_XXX with a LCD connected to J15? The thing is, that the FRAM module does not wrap a whole start->r/w->stop cycle in one function, for the advantage of subsequent r/w without sending the address again. So I need a guideline which module/mios - functions are save to call during such a session.

The faster IIC-protocol implementation uses RC4/5 by default, I think there I'll not meet this problem (?).

[TK.]

J4.SD is exclusively used by the IIC handler, while J4.SC is available on the LCD and J10 (application specific) port as well. This port is used by MIDIbox SID for example, according to the pin list, it's a class H pin

RC4 and 5 are class G pins. It's used by some applications, but I guess that you will support a "safe mode" for mapping to shared pins anyhow?

Best Regards, Thorsten.

[This N°9]

J4.SD is exclusively used by the IIC handler, while J4.SC is available on the LCD and J10 (application specific) port as well. This port is used by MIDIbox SID for example, according to the pin list, it's a class H pin

So calls to MIOS_LCD_xxx  and any IIC-related functions are not save during a FRAM-session. Which are the functions/modules that use the IIC port (besides MIOS_Bankstick_xxx and MIOS_IIC_xxx)? I just would like to document this in README.txt of the module.

I guess the ISR will never manipulate any of these PINs (J4 SD/SC and J10 SO/RC), even not in applications like SID?

but I guess that you will support a "safe mode" for mapping to shared pins anyhow

I first decided not to do this, because this will allocate additional code space. But on the other hand it's just some instructions that would have to be called in the app if there's no save-mode-functions. Anyhow, the ability to do subsequent reads/writes and to handle data between two read/write calls is a big advantage, so I would like to have a good documentation about what can be done in a FRAM session and what not.

[TK.]

Which are the functions/modules that use the IIC port (besides MIOS_Bankstick_xxx and MIOS_IIC_xxx)?

no other functions

I guess the ISR will never manipulate any of these PINs (J4 SD/SC and J10 SO/RC), even not in applications like SID?

In my own applications an ISR never accesses these pins

Best Regards, Thorsten.

[This N°9]

thanks.

looking at the MIOS Pin List, I found a little "bug":

"RD4 / E / J10:SO" instead of "RD4 / E / J14"

and in the description of RA4 there should be mentioned that also MIOS_Bankstick_* functions use the PIN. Same for RD5 "clock output to bankstick" -> "clock output to bankstick / IIC".

[TK.]

looking at the MIOS Pin List, I found a little "bug":

"RD4 / E / J10:SO" instead of "RD4 / E / J14"

fixed

and in the description of RA4 there should be mentioned that also MIOS_Bankstick_* functions use the PIN. Same for RD5 "clock output to bankstick" -> "clock output to bankstick / IIC".

I replaced BankStick by "functions which get use of the IIC port"

Best Regards, Thorsten.

[stryd_one]

You might like to refer to the pin list on the wiki as it already had this fix, and it has extra info, and the ability for you to add your own, that may be useful :)