[linuxsh-dev] Re: [linux-sh:01760] SH4 hardware problem

[Doug M. <mar...@sy...>]

Barkuson,

The /RDY line should be idled low and actively driven high when the user =
wishes to add extra wait states beyond what is required through the bus =
state controller(BSC).  The BSC acts differently then expected.  First it =
waits the required number of cycles programmed within the BSC in WCR2(wait =
control register 2) then it samples /RDY waiting for that line to be =
asserted.  After that line is asserted it will end that cycle successfully.=
  The default mode, which is what you will observe at reset time, is 15 =
cycles inserted and then wait for /RDY assertion.

Change your hardware to idle /RDY low during at least CS0 accesses.  =
Hopefully this helps.

Doug Martens
Senior Design Engineer
mar...@sy...
1000 Waverley St.
Winnipeg, MB, Canada
R3T 0P3
Symbol Technologies, Winnipeg
Ph: (204) 478-8046
www.symbol.com


>>> Barkuson <bar...@ya...> 07/04/01 12:58PM >>>
Hi Doug:

Thanks for your help, you are a life saver.
I went through the following pins and tried different
settings. Unfortunately, the address line still does
not advance from reset address 0x00000000.

>First a couple of questions;
>    1. What is the state of /RDY?
This pin is pulled high, and sits on high.

>    2. What is the state of /MRESET?
This pin is also pulled high and sits on high.

>    3. What is the state of /TRST?
This pin is pulled low. If this pin is pulled high,
the CPU stays in reset status.

>    4. During power up reset and operation what was
>the mode pin settings, and was the correct timing
>observed?
The mod pins are as followed:
MOD0 high
MOD1 low
MOD2 high   (for 6:3:3/2 clock setting)

MOD3 high
MOD4 low    (8 bit for Area 0 - 8 bit Flash memory)

MOD5 high   little endian
MOD6 high   normal memory
MOD7 high   master
MOD8 high   crystal resonator

Orignally, the 1.95 is brought up around 200ms after
3.3V, the reset line becomes high at the same time as
the 1.95V.
The reset circuit was modified, now, the reset line
comes up 150ms after 1.95V is up.=20

>    5. What type of memory and in what configuration
>is the memory configured?
Area 0 1MB FLASH memory 10MHz (8bit data bus)
Area 3 8MB SDRAM 100MHz  (32bit data bus)
Area 4 512kB SRAM 100MHz (32bit data bus)

>Getting the board to read the reset vector is the
>first hurdle.  The second hurdle with the SH4 is the
>proper start timing configuration for DRAM/SDRAM!

Is there anything else I should look out for??? I
suppose that this can only be a hardware problem (pin
settings). Since that bus should read at least 2 8-bit
data from the Flash memory before the first
instruction is fetched for execution. Is this true??

Thanks again,=20

Mark



--- Doug Martens <mar...@sy...> wrote: > First
a couple of questions;
>     1. What is the state of /RDY?
>     2. What is the state of /MRESET?
>     3. What is the state of /TRST?
>     4. During power up reset and operation what was
> the mode pin settings, and was the correct timing
> observed?
>     5. What type of memory and in what configuration
> is the memory configured?
>=20
> Getting the board to read the reset vector is the
> first hurdle.  The second hurdle with the SH4 is the
> proper start timing configuration for DRAM/SDRAM!
>=20
> Doug Martens
> Senior Design Engineer
> mar...@sy...
> 1000 Waverley St.
> Winnipeg, MB, Canada
> R3T 0P3
> Symbol Technologies, Winnipeg
> Ph: (204) 478-8046
> www.symbol.com
>=20
>=20
> >>> Barkuson <bar...@ya...> 07/04/01 08:42AM
> >>>
>=20
> Hi,
>=20
> Firstly, my apologies for sending this mail if this
> is
> not relevent to the mailing list. However, this is
> quite urgent, sorry. Could any hardware people help
> me
> out please?
>=20
> I have a custom Sh4 (SH7750) board which has not
> been
> able to run :(. Everything looks alright except that
> the board boots up and sits at address 0x00000000
> (the
> data at this address in the flash memory is on the
> data bus). The CPU seems to halt at this point with
> the following board status,
>=20
> - both main crystal and rtc crystal running
> - both status pin at low level
> - all NMI and IRL pins pulled up
> - BREQ pulled up
> - address sits at 0x00000000 and does not increments
> - CS0 low=20
> - RD low
> - all WE high
>=20
> Is there anything else that I should check?? or any
> setting that I could be missing??
>=20
> Can anyone direct me to a right place??
>=20
> All helps are greatly appreciated.=20
>=20
> Mark
>=20
>=20
>
___________________________________________________________________________=
__
> http://messenger.yahoo.com.au - Yahoo! Messenger
> - Voice chat, mail alerts, stock quotes and
> favourite news and lots more!
> =20

___________________________________________________________________________=
__
http://messenger.yahoo.com.au - Yahoo! Messenger
- Voice chat, mail alerts, stock quotes and favourite news and lots more!