Switching mini-flexbus modes during runtime on M5225x, M52259

[juanee]

Hello everyone,

I am new to the M52259 Coldfire and I have read the AN3854 Mini-FlexBus.pdf (Rev. 0, 04/2009) application note concerning this topic.

My question... am I able to switch mini-flexbus modes (non-multiplexed to multiplexed and back again) at any time during runtime?

The reason:  I wanted to control an asyncronous RAM (that has a 16 bit data bus) and a Flash NAND (that has an 8 bit data bus), but I wanted to have 16 bit data access to the RAM).

thanks,

juanee

[usingbothmuxand]

Hi everybody,

           Anybody plz reply me.

Is FB_ALE/FB_CS1_BAR may work as FB_ALE in mux mode and FB_CS1_BAR in non-mux mode for different chip selects at run time? Bcs i need minimum two chip selects in my system...

Is My design right?

Thanx...

[scifi]

Hi Juanee,

Have a look at register definitions for CSCR0 and CSCR1. You will find that each chip select has independently configurable multiplexed mode and bus width.

Regards,

- mike

[juanee]

Hello Mike,

I read what you suggested and I understand better now how it works.  Thanks.

But, another question though...

Am I able to switch back and forth between the mini-flexbus mode and general purpose IO (PTE, PTF PTG, etc) during runtime?

Thanks,

juanee

[juanee · Accepted solution]

"Am I able to switch back and forth between the mini-flexbus mode and general purpose IO (PTE, PTF PTG, etc) during runtime?"

To answer my own question, the answer is YES.  I have an external memory on the mini-flexbus that also needs the PTE, PTF ports as GPIO (to interface to another device).

Juan

Codewarrior 10 Special Edition

Windows XP Pro

MQX 3.6.2

PEMicro USB ColdFire Multilink.

Custom Target based on Coldfire MCF52259.

[scifi]

---

juanee wrote:

Am I able to switch back and forth between the mini-flexbus mode and general purpose IO (PTE, PTF PTG, etc) during runtime?

---

I think you should be able to do this. I haven't tried this myself, though...

[usingbothmuxand]

I am facing same problem with this device.

my RAM is accessed as x8 bit and EoPDH device as x16 bit peripheral.

Is it possible to use FB_ALE/FB_CS1_BAR as FB_ALE in multiplex mode and as FB_CS1_BAR in non-multiplex while external devides are selecting by CS0 and CS1 signal?

See my block diagram...for that I have attached it.

FB_ALE/FB_CS1_BAR is routed to RAM and x16 latch by FB_CS0_BAR.

conditions is:::

if(FB_CS0_BAR==0)

            FB_ALE <= FB_ALE/FB_CS1_BAR       // to x16 latch

else

            FB_CS1_BAR <= FB_ALE/FB_CS1_BAR     // to RAM

Thanx...