Vybrid VF6x Software and Hardware issues

[judgeless]

For software development, I am using  the IAR Embedded Workbench for ARM 6.60.1.5104. Right now

I am having considerable difficulty getting the FlexBus interface to operate. I have some questions / comments:

1. Any reads to the FlexBus Configuration registers (FB_CSAR0, FB_CSCR0, FB_CSMR0, FB_CSPMCR) results in PSP Exception Fault. FlexBus Configuration register addresses start at 0x4001_E000. I am able to read other Vybrid configuration registers without getting an exception. What are valid base addresses that can be set via the FB_CSARn register. Right now I have a base address of 0x30000000.
2. According to the Vybrid Reference Manual Vybrid Reference Manual, Rev. 5, 07/2013, 8.6.8.5 Instantiation Information page 573, “By default, FlexBus clocks are disabled and have to be explicitly enabled by software” How is this done in the Vybrid  ??? What Vybrid configuration registers have to be setup for this ???
3. Any reads or writes to the base address 0x30000000, causes the Vybrid processor to “lock-up” without any fault indication. Communication between the Vybrid and the I-Jet Debugger is lost. I do not see any of the FlexBus signals change state (via scope).
4. Can the FlexBus interface and NandFlash both co-exist ? Right now I have disabled NandFlash to avoid and multi-plexed I/O overlap…
5. When I setup the IOMUXC for the FlexBus interface pins, do I need to set the SPEED, SRE, ODE, HYS, DSE, PUS, PKE, PUE, OBE and IBE in addition to MUX_MODE ?
6. Can I get some sample code for setting up the FlexBus interface for the Vybrid processor ? I see examples for the Kinetis, but are there differences between setting up FlexBus in Vybrid vs Kinetis ???

[naoumgitnik]

Hello Sean,

Before we proceed further (with a SW guy), let's verify your HW, please.

Are you using your board or our Tower one, please? - If ours, just general advice - please, verify that all the [optional] 0-Ohm resistors are installed on your interfaces of interest (refer to the posted Tower Module Schematic).

Its Reference Manual you can find here - Re: Precise documentation.

Sincerely, Naoum Gitnik.

[judgeless]

They developed their our own circuit board based on the TWRV65GS10 tower kit. Their circuit board, in addition, has an FPGA that is connected to the Vybrid processor via the FlexBus interface.

[naoumgitnik · Accepted solution]

Hello Sean,

I am afraid this is all we got. Hopefully it helps.

Sincerely, Naoum Gitnik.

[naoumgitnik]

Hello Sean,

As the Tower board Reference Manual states, its FlexBus interface's IOs are shared with (and used by) another interface making using FlexBus impossible:

• "Vybrid’s NAND Flash data pins are shared between its NAND Flash controller and FlexBus interface. However, due to lack of dynamical switching between the two interfaces, they are dedicated to NAND Flash in the TWR-VF65GS10."... "Since the two Vybrid’s interfaces, NAND Flash and FlexBus, share pins, and NAND Flash is used on the TWR-VF65GS10 board, the Flexbus pins are not routed to the Tower Elevator and unavailable for any custom connections."

Of course, these 2 interfaces can coexist if:

• it is not expected that they both operate simultaneously,
• layout is done so that "split" connections on the shared IOs do not act as stubs too long for the frequencies used (i.e. signal integrity is OK) for either interface, which is usually achievable if both NAND Flash and FlexBus peripherals are placed on the board close to each other.

Regarding the sample code - both Vybrid development platforms, Tower and Auto, have the FlexBus IOs used for something else, so it looks like, at least for now, you will have to start using the Kinetis' example. Quite possibly both processors have similar FlexBus block designs (maybe somewhat different register names...).

(timesyssupport, may you comment on the Vybrid FlexBus sample code, please?)

Sincerely, Naoum Gitnik.

[timesyssupport]

Hi Naoum,

Unfortunately, we do not have any sample code for Flexbus with Vybrid, nor have reviewed Kinetis Flexbus code, as Flexbus is not implemented in the Linux kernel for Vybrid.

Thanks,

Timesys Support